External Fuel Filter Mod - A Good Idea?

[rondob4]

In a previous post I discussed a near disaster caused by speed bleeders installed on my '99 RT by the previous owner (PO). Another issue, caused by the PO, was discovered by the tech during the same service: an abraded external fuel line near the right throttle body.

 

Said PO performed the fuel filter relocation modification popular among many on this forum, but improperly routed one of the fuel lines so that the throttle cable Y was hooking on it and wearing a hole in the line. Fortunately, the sheathing was not fully penetrated, but it was sure to become so over time.

 

Fuel line pressure is approximately 45psi, according to the tech, and a ruptured line immediately above the cylinder posed a significant fire hazard. Since my superpowers do not include "flaming on," I asked him to restore the fuel filter assembly to the stock configuration. He did so in about 30 minutes.

 

Both he and the service manager expressed their concerns with this type of modification, even if done properly. How much time, effort, and money does one save by putting the filter outside the tank? They stated that the service protocol dictates changing the filter every 24K, and it is a fairly quick procedure if done in conjunction with other preventative maintenance. The fact that the tech undid what the PO had done, and restored the original configuration in half an hour, lends credence to their opinions, IMO.

 

I'm beginning to believe many mods one sees on this and other forums are simply done for the sake of doing them.

 

Again, I welcome comments.

[Boffin]

Clearly you should be extremely careful routing the fuel lines if the external filter mod is done. You also need to be certain that you use the right type of fuel line and filter.

 

The mod is not however, about routine sevicing, it is to make road-side repairs possible if the filter should get plugged. It only takes one bad tank of gas to screw up the filter and the mod makes the difference between a quick fix and a trip to the dealer.

 

Cya, Andy

[smiller]

I'm beginning to believe many mods one sees on this and other forums are simply done for the sake of doing them.

 

I know I'm going to be in the minority here but I tend to agree with you. While it's no doubt possible for a properly-maintained fuel filter to strand you and undoubtedly it has happened (because just about every possible mechanical failure has happened to someone or another at one time or another) I would weigh the chances of this happening vs. the chances of an external fuel leak due to the additional hose lengths and clamps. Chances of both occurrences are perhaps small but over a large population I wouldn't be surprised if the chance of a leak was considerably higher than the chance of a sudden fuel filter failure. If I had my choice of worrying about one or the other I think I'd rather worry about a clogged filter than a stream of high-pressure gasoline being blown onto the exhaust.

 

It's just not that big a deal to change the stock filter. Personally I would do so at reasonable intervals an not worry about it beyond that.

 

Counterpoint to follow...

[Jerry Duke]

Until you've changed a fuel filter on an Oilhead, you can't begin to appreciate a properly routed external fuel filter.

[AviP]

Until you've changed a fuel filter on an Oilhead, you can't begin to appreciate a properly routed external fuel filter.

[Bob Palin]

Until you've changed a fuel filter on an Oilhead, you can't begin to appreciate a properly routed external fuel filter.

I agree, I hope never to take that stupid panel out of my tank again, I also like the fact that I only have to take the tank off every 2 years now. I will check my fuel lines very carefully for any rubbing next time the fairing comes off.

[bartster]

Personally I think the external fuel filter mod is a great idea. I for one have broke down in the middle of the desert because of a plugged fuel filter. Also I would like to shake the man or womans hand that can change out the filter in half an hour! I`ve made the mod myself with no problem. With careful planning and forethought it should pose no problem. Just my two cents worth. Ride Safe Detroit

[Bob Palin]

Also I would like to shake the man or womans hand that can change out the filter in half an hour!

If you already have the tank off and you've changed 100s of them I think it could be done, starting from a bike in one piece it's impossible.

[smiller]

With the tank off I think any experienced mechanic could replace the filter in a half hour, although I personally take more time than this because I like to use the opportunity to check things over carefully. For instance last change I noticed that the fuel pump input screen had hardened over time and had developed a crack, and was allowing unfiltered fuel into the fuel pump. Glad I didn't let that go for two years...

[Bob Palin]

For instance last change I noticed that the fuel pump input screen had hardened over time and had developed a crack, and was allowing unfiltered fuel into the fuel pump. Glad I didn't let that go for two years...

Hmm, last time I took my tank off when the bike was just over 3 years and 90K old that screen looked and felt like new.

[Joe Frickin' Friday]

I will check my fuel lines very carefully for any rubbing next time the fairing comes off.

 

THIS is the key: regular inspections of any non-standard mods (actually, the whole bike should be thoroughly looked over during any service).

 

I've got 90K miles on my RT since I did the external filter mod. My only "oops" was not tightening one of the clamps in the fuel tank tight enough, causing the hose inside the tank to pop off in Podunk, Wyoming in '04 (3 years after having done the mod). But that's nothing unique to the external filter mod; that could have just as easily happened if I had been replacing the filter inside the tank.

 

A half hour is pretty fast for swapping an in-tank filter, especially if the bike is not equipped with quick-disconnects. Not only that, but you've got to do it when your tank is almost empty, otherwise the tank is pretty heavy to take off of the bike.

[Roger D]

In a previous post I discussed a near disaster caused by speed bleeders installed on my '99 RT by the previous owner (PO). <snip>

 

In your previous discussion of SpeedBleeders you never clearly established that it was the SpeedBleeders themselves that caused the problem. A more likely cause was the FAULTY installation of the SpeedBleeders.

 

Re: the fuel filter relocation...Agan there are indications that the PO screwed this up too. So the pattern seems to be that of a mechanic of dubious skills performing "unofficial" modifications. (We have at least two data points on this now...Speedbleeders and fuel filter relo.) Given the evidence of many (hundreds?) of folks on this site who have performed the modifications successfully, the conclusion I reach is NOT that the mod recommendations are flawed, but that their implementation by amateur mechanics is risky.

 

The moral of the story this: Buyers should have their potential purchases thoroughly checked out by a competent mechanic BEFORE they buy the bike (and especially where modifications have been made by the PO of unknown mechanical skill).

[smiller]

Given the evidence of many (hundreds?) of folks on this site who have performed the modifications successfully, the conclusion I reach is NOT that the mod recommendations are flawed, but that their implementation by amateur mechanics is risky.

 

I agree, and that is kind of what I was trying to imply... I just didn't want to use the word amateur. Bob and Mitch are right in that if you engineer everything exactly right, make no mistakes or oversights during installation, and inspect regularly then there is no reason to believe that your bike will go up in flames. It's just that I don't find swapping the stock fuel filter that much of a difficulty since I do it during a routine maintenance when I have the bike apart, and I like to get the tank off once in a while to inspect things anyway. But if one finds changing the filter that onerous and feels that the the time and effort to fit an external filter is worthwhile then have at it I guess... just make really sure that you understand what you are doing.

[Bob Palin]

if you engineer everything exactly right, make no mistakes or oversights during installation, and inspect regularly then there is no reason to believe that your bike will go up in flames.

Oh oh, I expect my bike to explode at any moment

[PETDOC]

Just a couple of comments. I did my first FF change on my '04 GS and it was an agonal experience taking 4.5 hours start to finish (ie, tank on bike with gas). Now that I know what to expect and have replaced the 4 BMW clamps with screw clamps I feel certain I can do it in 1.5 hours. If one chooses not to replace rubber O ring (probably not a good idea) I believe FF change can be done in 30 minutes.

Second comment regards frequency of changing FF. My fuel pump began to sing around 10-11,000 miles and I had seen several posts warning that shortly after singing began riders ended up with a total shut down from a clogged FF so at 12,400 miles I changed the FF and singing went away. I've seen other posts where people have ignored singing with no bad effect, but I just didn't want to risk it.

[Roger D]

I agree, and that is kind of what I was trying to imply... I just didn't want to use the word amateur. <snip>

 

Point taken. I'm sure many of us have run into "professional" mechanics who had less skill than "amateur" mechanics we know. So to put it more precisely, "...the conclusion I reach is NOT that the mod recommendations are flawed, but that their implementation by sloppy or poorly-skilled mechanics is risky.

[RFW]

The potentially disasterous problem with an external filter (not in the tank, if this is what you are referring to), is NOT the 45psi of fuel line pressure.

 

The problem is the backpressure on the filter, which can reach astronomic levels if you are not careful.

 

My K100 had a problem last summer where the pump started whining like a banshee. The problem was that the filter was plugged, and the pump had to develop almost 150psi (YES!!!) pressure to get the fuel past the filter (~100 psi to overcome filter backpressure, in addition to the normal fuel rail pressure). This means that the filter housing itself was pressurized to almost 150psi! No wonder these housings are known to split!

 

Yet, the bike ran just fine since the fuel rail still had the normal pressure; the injection system had no way of "knowing" how high the filter backpressure was!

 

But my point is this: If the filter is in the tank, and it burst as a result of this extreme prssure, then there is no damage done (other than you being stranded). If it bursts OUTSIDE the tank, you may well have a very large bonfire!

 

So if your filter is on the outside of the tank, check its backpressure often!!!

 

To check the filter backpressure, pull the outlet hose off the filter, and allow the filter to dump straight into the tank. Then "T" a cheap pressure gauge into the filter inlet hose. Turn on the ignition key (you may need to hit the starter with a brief stab). This will start the pump running for a few seconds. If the pressure gauge reads more than 10 to 15 psi, replace the filter! How often you need to replace it can depend on if you run onto a "bad" batch of gas.

 

Bob.

[Jim VonBaden]

I have also seen two occasions where the weak point wasn't the filter, but the screws holding the plate in place on the tank. On the GS they are (welded?) onto the tank, and the cheap nuts, with nylon locking inserts can easily strip out, or the studs can break off.

 

The more often you do this, especially as a roadside repair, the more likely you are to have a problem involving the mounting studs.

 

Of course the others have mentioned the other advantages to the mod.

 

Jim

[Ken H.]

I did it to our RT on the same pretext that if I ever had to do a filter replacement along the side of the road it would be easy. And I carried a spare filter. And I never had any issues with the installation.

 

But later I got to thinking about all the millions of cages on the road also with the filter in the tank that never gets touched in 100,000 and concluded the whole thing is basically a solution looking for a problem.

[John Dickens]

My personal view is that the external filter mod is the single best piece of advice I've got from this and the IBMWR BBS's.

 

I hope never to have to remove the tank panel ever again.

[Steve W.]

I did the external filter mod on my long gone RS11. It worked great for many 1000's of miles. Just use the fuel injection rated hose and the fuel injection clamps, not the worm type. THINK about the hose placement and use ty-wraps to secure it safely. I will do my GS when the time comes. A really great mod if done properly.

Steve

[RFW]

I did the external filter mod on my long gone RS11. It worked great for many 1000's of miles. Just use the fuel injection rated hose and the fuel injection clamps, not the worm type. THINK about the hose placement and use ty-wraps to secure it safely. I will do my GS when the time comes. A really great mod if done properly.

Steve

 

It's not the hose that is the problem. A good hose can easily hangle more pressure than the pump is capable of.

 

It's the filter itself! If it gets plugged, the pump can easily get up to 150 to 200psi trying to force fuel through a clogged filter. This is exactly what happened to me. The bike will still run just fine, since the fuel injector rail still has the normal regulated pressure.

 

The problem is that the aluminum fuel filter canister was NEVER designed for this kind of pressure. In fact, some time ago, BMW discontinued one manufacturer of filters, because they stamped the part number into the housing, thus weakening it. These filters were known to split open under pressure.

 

So if you do an external mod, then be damned sure you check your filter regularly. If it gets plugged, the pressure the pump is capable of can most certainly result in it splitting open.

 

Bob.

[Jim VonBaden]

I did the external filter mod on my long gone RS11. It worked great for many 1000's of miles. Just use the fuel injection rated hose and the fuel injection clamps, not the worm type. THINK about the hose placement and use ty-wraps to secure it safely. I will do my GS when the time comes. A really great mod if done properly.

Steve

 

It's not the hose that is the problem. A good hose can easily hangle more pressure than the pump is capable of.

 

It's the filter itself! If it gets plugged, the pump can easily get up to 150 to 200psi trying to force fuel through a clogged filter. This is exactly what happened to me. The bike will still run just fine, since the fuel injector rail still has the normal regulated pressure.

 

The problem is that the aluminum fuel filter canister was NEVER designed for this kind of pressure. In fact, some time ago, BMW discontinued one manufacturer of filters, because they stamped the part number into the housing, thus weakening it. These filters were known to split open under pressure.

 

So if you do an external mod, then be damned sure you check your filter regularly. If it gets plugged, the pressure the pump is capable of can most certainly result in it splitting open.

 

Bob.

 

I think this is sensationalism. Hundreds have done this mod with no problems. I have only once heard of a filter bursting, and it was a non-FI filter.

 

Besides, the hoses wont take 200 PSI either. Not that I have heard of this before, though I am not saying it hasn't happened.

 

Jim

[No_Twilight]

It's the filter itself! If it gets plugged, the pump can easily get up to 150 to 200psi trying to force fuel through a clogged filter. This is exactly what happened to me. The bike will still run just fine, since the fuel injector rail still has the normal regulated pressure.

 

The problem is that the aluminum fuel filter canister was NEVER designed for this kind of pressure. In fact, some time ago, BMW discontinued one manufacturer of filters, because they stamped the part number into the housing, thus weakening it. These filters were known to split open under pressure.

 

Bob,

Where did you hear this? Your story reeks of urban legend, old wives tale, and folklore. First, I don't think our filters are made of Aluminum, I think they're SS. Second, has anyone ever taken one out of their tank that was busted? I've heard of lots of filters getting so plugged that the bike wouldn't run. Why didn't they burst? Third, your statement that the weren't designed to take this pressure sounds like BMW forgot to hire engineers. Any engineer worth his salt would design a filter that can plug to take max system pressure (shutoff head of the pump).

 

cheers,

Jerry

[No_Twilight]

Another issue, caused by the PO, was discovered by the tech during the same service: an abraded external fuel line near the right throttle body.

 

Said PO performed the fuel filter relocation modification popular among many on this forum, but improperly routed one of the fuel lines so that the throttle cable Y was hooking on it and wearing a hole in the line. Fortunately, the sheathing was not fully penetrated, but it was sure to become so over time.

 

I'm beginning to believe many mods one sees on this and other forums are simply done for the sake of doing them.

 

I didn't see your speed bleeder post so I can't comment other than to say that speed bleeders are a great thing for a man who bleeds his brakes by himself. If you pay the dealer to do it, they don't need them and they won't have anything nice to say about accessories designed to take work away from them.

 

As for the external fuel filter mod. Indeed the fuel lines have to be routed carefully and checked occasionally. I posted photos of how I routed mine and I like it's location much better than some of the other I've seen. You don't seem to be inclined to do your own work so the need for these do-it-yourself mods isn't there. I wonder why you're even reading and posting here if you're inclined to just take your bike into the dealer and pay full fare? This is a location where do-it-yourselfers share tips on how to do it better and easier. Have you ever done the fuel filter change inside the tank? Didn't think so. As for the 30 minutes, I'd say he gave you a deal. Call him and ask how much the labor is on just changing out the fuel filter. My guess is he gave you the deal because he knew he was creating future work for yourself. I'm sure in the future, he'll have nothing good to say about any do-it-yourself mods anybody's done.

 

Maybe you can tell that I've never had a good dealer experience.

 

Cheers,

Jerry

[No_Twilight]

One more thing: You should probably inspect and consider fixing or paying the dealer to fix anything else that this PO did. It appears he wasn't the most accurate tool in the box. --Jerry

[Bob Palin]

First, I don't think our filters are made of Aluminum, I think they're SS.

That may be true but many of us use a non-BMW filter once we've done the external mod, as long as it is designed for FI use it should be fine, mine is a Purolater (I think) and appears to be made of aluminium. I suspect somebody's faulty filter exploded once and that has grown into the urban legend, many vehicles have external fuel filters.

[ShovelStrokeEd]

While we are dispelling urban legend, lets look at another fact. The ignition temperature of gasoline is somewhere around 425 degrees F (232C). It is not likely, unless the bike has been running very hard or left idling for an extended period that any part of the motor or even the exhaust piping is that hot. Therfore, unless you go looking for the source of the smell with a lit match, you have no worries about a filter bursting or a line coming off from the fire aspect.

[GCD]

I am one who did the external feul filter mod on my RT, rode for a season with it, and went back to the original in-tank setup. Here's why:

 

1. I learned of filter ruptures in the past from a very experienced and reliable independent BMW certified wrench;

 

2. On my RT, the only place I found to mount the filter remotely was zip tied to the rear subframe next to the shock preload adjuster. I reasoned that back there it is exposed to possible encounters with road debris, much wider extremes of heat and cold, and the 24" or so of fuel line was inherently less safe than the in-tank setup.

 

3. If the filter ever were breached, the fuel would spray all over the rear tire, maybe giving me another problem at a bad time.

 

4. If I sold the bike, and the remote filter mod had caused someone else to go up in flames, I didn't want anyone to be responsible, either in my own mind or legally.

 

I still carry an extra flter and O ring while touring, as well as two fuel line clamps so the tank can come off as quickly as possible. Of course, all of the clamps on my bike are the screw type now too.

 

I don't worry about the filter mod any more now.

 

 

Greg DeWit

Evergreen, Colorado

[smiller]

While we are dispelling urban legend, lets look at another fact. The ignition temperature of gasoline is somewhere around 425 degrees F (232C). It is not likely, unless the bike has been running very hard or left idling for an extended period that any part of the motor or even the exhaust piping is that hot. Therfore, unless you go looking for the source of the smell with a lit match, you have no worries about a filter bursting or a line coming off from the fire aspect.

I think the concern isn't so much that the fuel will spontaneously ignite just because it comes into contact with something hot (which it won't, as you point out), but that a stream of fuel hitting e very hot surface will quickly evaporate and create a gaseous fuel air mixture that would seem to at least have the potential of being quite dangerous since the fuel would be very easy to ignite in that condition. In any event I would consider raw fuel leaking onto a running engine to be somewhat of a cause for concern... but maybe I'm just being too careful...

[leikam]

The problem with fixing a clogged fuel filter on the side of the road isn't so much that the gas tank is a pain to remove. It's that you can't remove the pump assembly with a full tank. Realistically, you're most likely to get a clogged filter after filling up with bad gas, so chances are high that you'll have too much in your tank to do it cleanly. If your filter is in the tank, you're going to need to dump most of the tank into the grass. Let's suppose you do this and swap out the clogged filter for the new one you've toted around for the last 50k miles. What do you do now? You've got an unknown amount of gas in the tank and it will probably clog your filter again in short order.

 

What an external filter buys you is less time standing (or kneeling more likely) on the side of the road, a clean way to swap filters, conservation of fuel, and a convenient way to bypass the filter, should that be necessary, until you can get back to civilization. None of that is compelling in one's own garage, but it's all important at sundown on a Sunday in the middle of nowhere.

[rondob4]

I didn't see your speed bleeder post so I can't comment other than to say that speed bleeders are a great thing for a man who bleeds his brakes by himself. If you pay the dealer to do it, they don't need them and they won't have anything nice to say about accessories designed to take work away from them.

 

I watched the tech bleed the brakes by himself, using the stock bleeders, so I can't see much validty in that argument. And since the service manager is there to make money, why shouldn't he say that? Simply because he expresses an opinion, like you and I, doesn't mean anyone has to accept it.

 

You don't seem to be inclined to do your own work so the need for these do-it-yourself mods isn't there. I wonder why you're even reading and posting here if you're inclined to just take your bike into the dealer and pay full fare? This is a location where do-it-yourselfers share tips on how to do it better and easier. Have you ever done the fuel filter change inside the tank? Didn't think so. As for the 30 minutes, I'd say he gave you a deal.

 

The 30-minute filter change was do-able because he already had the tupperwear off and the tank was almost completely empty. And you're right -- I'm disinclined to do much maintenance or repair work because I prioritize my time elsewhere. To each his own. My original point was to poll the audience on the perceived utility, or lack thereof, of such a modification given the potential for catastrophic failure (again my opinion) if something goes wrong. Of those who chose to write, the opinions are fairly split.

 

While you are correct in stating that "This is a location where do-it-yourselfers share tips on how to do it better and easier," I've also found it to be a forum that gives members cause to think and evaluate what they choose to do with, and to, their bikes. Our goals are both well-intended.

 

I had a great experience at this dealership, so much so that I sent a note off to BMW Motorrad. There are four dealers all about the same distance from my house, yet I will be going back to see this one. PM me, if you like, and I'll tell you who and where they are.

 

Rondo

[RFW]

Bob,

Where did you hear this? Your story reeks of urban legend, old wives tale, and folklore. First, I don't think our filters are made of Aluminum, I think they're SS.

 

The gas filter housing in my K100, and all other BMW genuine gas filters I have seen in the local parts department, are ALL made of impact-extruded aluminum. To make a part like a relatively cheap, disposable gas filter housing from SS would be a hell of an expensive undertaking, because SS cannot be extruded into ths shape, so it would have to be welded from several pieces. Try that with a paper cartridge inside!

Second, has anyone ever taken one out of their tank that was busted? I've heard of lots of filters getting so plugged that the bike wouldn't run. Why didn't they burst? Third, your statement that the weren't designed to take this pressure sounds like BMW forgot to hire engineers. Any engineer worth his salt would design a filter that can plug to take max system pressure (shutoff head of the pump).

"Would have" and "could have" do not count in the real world. It is a fact that BMW changed the part numbers of the filter that the K100s, used some time ago. The change was that the new filter had its indentification screen printed on it, and had a slightly more robust housing. The old filter had its ID (and the BMW logo) stamped into the housing. The reason for the change was that there had in fact been reports of burst housings. I have more details describing this somewhere.

 

As for your "engineers" comment, BMW does not design fuel filters. They buy them as a commodity item from filter manufacturers like Knecht. BMW also does not design pumps. They buy them from Bosch. It doesn't take a genius to see the potential of a "disconnect" here.

 

In my own case, the plugged filter in my K100 measured ~150 psi internal pressure, and when looking at the aluminum housing (and yes, it is alu!) there were some signs of stress. Later out of curiosity I cut it apart, and as a mechanical engineer, I can tell you that I would not trust this thin aluminum filter housing to reliably tolerate this level of pressure.

 

Bob.

[Deadboy]

I hesitate to wade into the middle of this but honestly I think the speed bleeders and fuel filter re-location are just solutions in search of problems...my RT has 30K now and hasn't seen the inside of the dealership since it's 600 mile service.

 

I did my fuel filter at a tech daze and it took around 45 minutes (plastic already off). The brake and wheel circuit bleed is also no big deal, I do the entire system every year and the savings in time the speed bleeders provide seem negligible at best...as long as you have two people there (and what tech daze is short of people?)....I applaud those who spend the time thinking up these solutions, but seriously doubt very many folks have really seen much benefit from the external filter mod...unless you are heading to Baja soon I think the odds of dirty fuel from a name brand station are pretty darn rare...as one of our gurus at the tech daze pointed out the fuel filter in his F-150 is the same size and has something like a 150K service life....

 

If it makes you feel better on the road then I say go for it, but short of a rash of plugged filters I will leave mine in the tank.

[DavidEBSmith]

Yes, there were BMW filters that had a propensity to burst, years ago. And early K-bikes (and Laney's) had a propensity to smoke on startup if they had been sitting on the sidestand. And both these issues (and others) are embedded in the collective consciousness of BMW owners and will forever be applied to everything that comes out of Germany with a blue-and-white roundel on it. BMW owners are like a cargo cult - we keep repeating the same old warnings over and over, and have long since forgotten why. 50 years from now, some newbie will park his dilithium-crystal-powered Beemer on the sidestand and some old fart will tell him to put it on the center stand, and not to install an external plasma filter because it will burst.

 

I'm not a mechanical engineer, but I would have to think that FI fuel filters are designed to not burst at high pressures, because even if they burst inside the tank, it's a bad thing, leaving the vehicle disabled (albeit not in flames). The bad K bike fuel filters were defective for use in the tank or out of the tank. BMW (or their supplier) stopped stamping numbers into the body of the filter, and fixed up the seal between the two halves of the filter. That solved the problem. And I'm not so sure that (as the collective wisdom holds) that they moved the filter inside the tank simply because some filters burst. Equally valid reasons would be to save space, simplify the fuel line arrangement, or to be able to buy the whole thing as one assembly from their supplier. There's lots of fuel injected vehicles with external fuel filters, and those manufaucturers don't seem too concerned about bursting filters.

 

Personally, the peace of mind that I get from knowing that, if I'm in the middle of nowhere and I get some bad gas, I can replace the fuel filter in about 10 minutes on the side of the road, outweighs any concern I have about the filter bursting or my bad wrenching in installing the external filter. I've gotten bad gas in vehicles, but I've never seen a fuel filter burst.

 

Now I just have to figure out how to make my external fuel filter and the two adjusters on my new Wilbers shock all live in peace and harmony.

[Ken H.]

I hesitate to wade into the middle of this but honestly I think the speed bleeders and fuel filter re-location are just solutions in search of problems...

Yeah, I'm with you. I jumped on both those bandwagons originally and have since jumped back off.

 

ISFA the fuel filter one, I think one could make an argument that the filter may be less likely to clog when in the tank. It would be along the lines of how the filter probably backwashes fuel back into the tank itself a bit every time the system pressures down at shut off.

[BUSTED]

Most often the filter will be clogged by water, not dirt. Annual maintenance or other routines guarantee nothing. A new filter today is just one "bad gas fill-up" from stopping a rider. For a rider that relies on dealer service this could be a problem as many are closed on Mon, and have limited service on Sat, you could have a plugged filter Fri. afternoon and wait until Tuesday to talk to a service manager. Been riding oilhead RT's since they came out and had external filter mod by me since 1996. I carry a spare filter in the tail section. NO fires and NO leaks. No problems with the "totaled out" RT when hit head-on with a full tank of gas minus 10 miles. I helped a friend change out a stock filter once along side of road. It wasn't pretty or fun. You will even find yourself hoping no one tosses a butt out and igniting the gas you had to dump out of the tank.

[smiller]

A new filter today is just one "bad gas fill-up" from stopping a rider.

 

The oilhead filter is the same as that used in many automobiles yet you don't see cars stranded very often because of one "bad gas fill-up". Why would the chance of it be that much worse on a bike?

[RFW]

ISFA the fuel filter one, I think one could make an argument that the filter may be less likely to clog when in the tank. It would be along the lines of how the filter probably backwashes fuel back into the tank itself a bit every time the system pressures down at shut off.

 

Actually, no. In or out of the tank does not make any difference to the filter's operation. "Backwashing" is impossible either way. In either type of installation, you have a pump, pushing fuel through a filter (either in or out of a tank), and from there through the external fuel rail (where fuel is tapped off for the injectors), then through a pressure regulator (to maintain the required fuel rail pressure), then finally back to the tank.

 

Fuel is physically (and intentionally) prevented from flowing backwards through the pump (whether the pump is operating ot not), thus backflow from the filter back into the tank is impossible.

 

Bob.

[RFW]

A new filter today is just one "bad gas fill-up" from stopping a rider.

 

The oilhead filter is the same as that used in many automobiles yet you don't see cars stranded very often because of one "bad gas fill-up". Why would the chance of it be that much worse on a bike?

Valid point. But for my part, I never said it happened "often". Only that it was possible for the filter to burst and there was a history of exactly this with some (earlier?) BMW-supplied filters.

 

Maybe the potential fire hazard caused by a burst filter is one reason why so many cars have their fuel filters located in their gas tanks?

 

Bob.

[No_Twilight]

I'm not a mechanical engineer, but I would have to think that FI fuel filters are designed to not burst at high pressures, because even if they burst inside the tank, it's a bad thing, leaving the vehicle disabled (albeit not in flames).

 

Now I just have to figure out how to make my external fuel filter and the two adjusters on my new Wilbers shock all live in peace and harmony.

 

Exactly. It doesn't take an engineer to realize what the design criteria for a part need to be. someday when I'm bored I'll take and old filter and pressurize it to burst and see what pressure that is...

 

As for routing of your hose...I posted a photo of my routing but wasn't good enough with the search feature to find it so here it is again. I used the factory u-bend installed under the filter in the tank to turn the outlet around and sent it back parallel to the inlet thus keeping the filter out of the congested area between the TB and the Cylinder...

 

Ooops, I've taken the anti-mod thread and turned it into a mod thread...can't teach old dogs new tricks...and I'm moving toward that crotchety old bastard phose of my life...I can feel it.

 

Cheers,

Jerry

[DavidEBSmith]

The oilhead filter is the same as that used in many automobiles yet you don't see cars stranded very often because of one "bad gas fill-up". Why would the chance of it be that much worse on a bike?

 

Well, I've been stranded twice in automobiles from bad gas, and zero times on the motorcycle.

 

Both times it happened when I ran the fuel level low, so it may be that in the automobile, if you fill up when the tank is half or 3/4 empty and get a shot of water or crud in the gas, there's more good gas left in the tank to dilute the bad stuff and the vehicle still runs OK. But with the smaller tank on the bike, or if the auto tank is almost empty, there's less good gas to dilute the bad stuff, more bad stuff in the gas, and you have problems.

[No_Twilight]

And BTW, there seem to be a lot of gas related problems in SoCal this winter. Two of my friends have had fuel filters plug up so badly their bikes would hardly run. Neither filter bursted. --Jerry

[PETDOC]

When I changed my FF on my '04 GS at 12,400 miles I found when I drained the tank I had some water in the fuel. Bike was 2 years old at the time. I've seen others post the same comment. Regardless of whether I ever move my FF outside of tank I,from now on, will drain my tank yearly to make sure any water that has accumulated is gone. Since it is a metal tank and hard to fill to the brim condensation has to occur with large temperature swings. Moral to this is keep bike's tank as full as possible in winter and you should be able to minimize water from condensation.

[BMWRich58]

The oilhead filter is the same as that used in many automobiles yet you don't see cars stranded very often because of one "bad gas fill-up". Why would the chance of it be that much worse on a bike?

 

Well, I've been stranded twice in automobiles from bad gas, and zero times on the motorcycle.

 

Both times it happened when I ran the fuel level low, so it may be that in the automobile, if you fill up when the tank is half or 3/4 empty and get a shot of water or crud in the gas, there's more good gas left in the tank to dilute the bad stuff and the vehicle still runs OK. But with the smaller tank on the bike, or if the auto tank is almost empty, there's less good gas to dilute the bad stuff, more bad stuff in the gas, and you have problems.

 

I had the same thoughts!

 

But...one of my reasons for the fuel filter mod has to do with the style of traveling I do. I usually stick to the back roads,cruising through "onehorse" kinda towns. I've stopped an gotten what ever gas was available from what ever dispenser they used,only because I had no choice.

Some pumps I've seen/used were probably older than dirt!!

"Credit Card,what's that?"...replied the grey haired owner.

I've even had the new modern stations dispense contaminated gas from post construction.. as in the summer of 2002 Rt 93 south,Jackpot Nevada to Lost Wages Midnite run!

Last summer up in the Yukon,some filling stations still had the old pumps without the added $1 symbol,so you can imagine the kind of maintenance the owners perform on they're equipment...!

[BMWRich58]

When I changed my FF on my '04 GS at 12,400 miles I found when I drained the tank I had some water in the fuel. Bike was 2 years old at the time. I've seen others post the same comment. Regardless of whether I ever move my FF outside of tank I,from now on, will drain my tank yearly to make sure any water that has accumulated is gone. Since it is a metal tank and hard to fill to the brim condensation has to occur with large temperature swings. Moral to this is keep bike's tank as full as possible in winter and you should be able to minimize water from condensation.

 

Alcohol will absorb the water...like in "Gas Line Anti Freeze".

A small amount of water won't harm you as much as "silt,sand etc" that makes it's way through the pump system into your tank,then clogging your fuel filter.

I believe also the cause of my fuel problem,was from the nylon sock filter "Missing" at the bottom of the underground tank. Bits and pieces of the sock were found in my tank along with some sandy/silt!

Thanks to our own "Gleno" who allowed me the use of his garage to make my repairs.

[RFW]

A small amount of water won't harm you as much as "silt,sand etc" that makes it's way through the pump system into your tank,then clogging your fuel filter.

I believe also the cause of my fuel problem,was from the nylon sock filter "Missing" at the bottom of the underground tank. Bits and pieces of the sock were found in my tank along with some sandy/silt!

Silt, perhaps, but sand no. The pump has an ultra-fine mesh screen covering its intake, and no sand can get through this. I suppose the idea is that anything fine enough to get past this screen (that looks fine as the finest silk) isn't going to harm the pump's rollers.

 

The filter comes after the pump, probably because the system couldn't possibly tolerate the pressure drop of a micron-filter in the suction line of the pump.

 

Bob.

[Jim VonBaden]

While we are dispelling urban legend, lets look at another fact. The ignition temperature of gasoline is somewhere around 425 degrees F (232C). It is not likely, unless the bike has been running very hard or left idling for an extended period that any part of the motor or even the exhaust piping is that hot. Therfore, unless you go looking for the source of the smell with a lit match, you have no worries about a filter bursting or a line coming off from the fire aspect.

 

 

This illustrates the pipes under somewhat extreme conditions.

 

Jim

[Clive Liddell]

Something that has not come up in this discussion is the fuel pump pressure relief valve. If some comments are to be believed then this must have been added by the accountants because engineers would never have thought of that!

 

Some data: After externalising my RT's filter (to under the seat and with the FI hose leading in a smooth run right around the engine and back to the connections via the space below the alternator) I decided to leave the OLD filter on and check amperages.

 

With battery voltage at 12.78 V

 

Old filter (62000km) 5.3 Amps

New filter (0km) 4.7 Amps

 

These currents are measured across the output terminals of the fuel pump relay - so there may be other current draws but it gives an easily measured reference.

 

I put the old filter in my lathe and neatly parted off the end (BTW these OEM filters are well made and have plenty of meat IMO). Stretching out the paper I found 5 or 6 tiny flecks of aluminium and no sign of any grit etc trapped so it could be rubbed off. The "active" portion of the paper looks darker than the ends but does not seem "blocked" ie. I can easily notice light and dark through the stained paper.

 

Oh, it took me 5 minutes to change filters

[RFW]

I decided to leave the OLD filter on and check amperages.

 

With battery voltage at 12.78 V

 

Old filter (62000km) 5.3 Amps

New filter (0km) 4.7 AmpsThe "active" portion of the paper looks darker than the ends but does not seem "blocked" ie. I can easily notice light and dark through the stained paper.

 

When I discovered the filter on my K100 was so plugged that the pump pressure had gotten up to ~150 psi, I did a similar check of the pump amperage, and got similar "before and after" results as you did. This points out an easy way to determine filter performance, and a way to see when to replace it: just measure the pump current consumption!

 

By the way, I also tore apart the plugged filter, and found also that one side of the paper element was rather greyish. I had expected something much more spectacular, considering that the filter was nearly plugged solid! As you mentioned, I could even see light through the paper.

 

I guess this shows that what plugs the filter is micron-sizes particles, that don't even block much light.

 

Bob.