Canisterectomy

[Fly4hire]

This summer during a x-country trip my evap canister clogged causing me a vacuum tank and crushed fuel sender unit.

 

I've read the various views on canister or not, but curious if rather than doing the whole canisterectomy, simply leaving the unit in place and lines intact, but unhooking the tank vent line and tucking up out of the way performs the same function and preserves the option for installing a new canister at a later point?

 

Is there any requirement for optinal performance to join various lines and plug others per the canisterectomy?

[Ken H.]

Yes it would.

 

The disconnected tank vent fuel line length may be an issue though as you really want it to reach all the way to the bottom of the bike in case of an overflow.

[smiller]

And be advised you can have some issues if you simply vent the tank directly to the atmosphere, as in liquid fuel can leak out of the vent line when the tank is full, or fumes can leak out the rest of the time (which will be noticeable if you park in an enclosed garage.) If you disconnect the vent line from the cannister you can install a one-way vacuum valve (available at any auto parts store) which will allow air to flow into the tank when required but not out.

[steve.foote]

And be advised you can have some issues if you simply vent the tank directly to the atmosphere, as in liquid fuel can leak out of the vent line when the tank is full, or fumes can leak out the rest of the time (which will be noticeable if you park in an enclosed garage.) If you disconnect the vent line from the cannister you can install a one-way vacuum valve (available at any auto parts store) which will allow air to flow into the tank when required but not out.

 

Seth, air has to be able to flow out of the tank to equalize expansion when the tank warms.

[smiller]

Seth, air has to be able to flow out of the tank to equalize expansion when the tank warms.

Well, ideally...

 

Yes, adding a check valve will cause some pressure build-up in the tank, but nothing terribly significant. On very hot days when the tank is really getting cooked by the engine you will get a 'pffft' when you open the fill cap (and under more normal/cooler conditions you don't really notice anything at all.) I've run it this way for quite some time with no damage or problems (and that's under Texas summer conditions, a pretty tough test.) It would probably be a more significant issue in a car with its much larger fuel tank volume, but it doesn't seem to be problematic on my bike.

 

Short of a check valve (or of course the cannister if you want to retain it) I can't think of any way to avoid venting directly to the atmosphere, and that seems to cause more problems (fuel on the ground, gas fumes in the garage) than any potential problems with a check valve, at least in my experience. Lesser of two evils I guess.

[Boffin]

Seth, air has to be able to flow out of the tank to equalize expansion when the tank warms.

Well, ideally...

 

Yes, adding a check valve will cause some pressure build-up in the tank, but nothing terribly significant. On very hot days when the tank is really getting cooked by the engine you will get a 'pffft' when you open the fill cap (and under more normal/cooler conditions you don't really notice anything at all.) I've run it this way for quite some time with no damage or problems (and that's under Texas summer conditions, a pretty tough test.) It would probably be a more significant issue in a car with its much larger fuel tank volume, but it doesn't seem to be problematic on my bike.

 

Short of a check valve (or of course the cannister if you want to retain it) I can't think of any way to avoid venting directly to the atmosphere, and that seems to cause more problems (fuel on the ground, gas fumes in the garage) than any potential problems with a check valve, at least in my experience. Lesser of two evils I guess.

 

The non-US market bikes vent to atmosphere via a rubber tube to the same point as the other vent lines on the bike. No valves, cannisters, solenoids. Just a tube. The rest of the world does not seem to have had a problem with this arrangement.

 

Andy

[DrPaul]

I performed the "canisterectomy" a few months ago. All vent lines go to atmosphere down behind the rear brake pedal and I bridged the TB nipples with a piece of rubber tubing. Now I can fill my tank to the max without fear of a canister malfunction and I've seen no gasoline leakage or vapor problems in the garage. FWIW.

[smiller]

The non-US market bikes vent to atmosphere via a rubber tube to the same point as the other vent lines on the bike. No valves, cannisters, solenoids. Just a tube. The rest of the world does not seem to have had a problem with this arrangement.

Really? That's interesting. But with nothing preventing fumes from exiting the tank I don't see how one could avoid a pretty strong gasoline odor when a hot bike is stored in a closed garage after shutdown. That's what I was experiencing and a check valve cured the issue entirely. Don't know... if you aren't experiencing any problems then don't worry about it I suppose.

[NonComp]

The non-US market bikes vent to atmosphere via a rubber tube to the same point as the other vent lines on the bike. No valves, cannisters, solenoids. Just a tube. The rest of the world does not seem to have had a problem with this arrangement.

Really? That's interesting. But with nothing preventing fumes from exiting the tank I don't see how one could avoid a pretty strong gasoline odor when a hot bike is stored in a closed garage after shutdown. That's what I was experiencing and a check valve cured the issue entirely. Don't know... if you aren't experiencing any problems then don't worry about it I suppose.

My R1100R is this way and is stock (as far as I can tell). There are two lines that come out behind the right foot peg. One is an overflow for the drain around the filler, the other is the tank vent. I don't notice any fumes when the bike is parked. But I did notice last weekend when the filler cap popped open after a fillup. At 70 mph I got a strong wiff of gas, looked down, saw it open and smacked it shut.

[smiller]

I think my issue may be due to environmental conditions, i.e. parking a hot bike in a very hot hot garage. It gets very warm here in the summer and a bike soaking in a 90-100+ degree garage probably vaporizes a good deal more gasoline than under more temperate conditions. Maybe I'll try an experiment and vent the tank directly (as apparently is the stock configuration outside of the USA) when it cools down here and see if the problem doesn't exist to the same extent, or at all.

[T__]

Gasoline Vapor pressure has a large effect on vapor smells after a hot run.. The higher the Gasoline vapor pressure the more likely it is to evaporate ( & smell) at low-mid to warm temps..

 

Gasoline Vapor pressure changes considerably in some of the colder climates as the seasons change with high vapor pressure fuel needed for good cold starts in cold weather.. Low vapor pressure fuel is used in the summertime & in high average ambient areas to prevent vapor lock & to help control evap emissions.. The vapor pressure can run from as low as 7 psi to as high as 15 psi by season & across the US..

 

Twisty

[John in NC]

Take the canister off. Mine got plugged and caused the fuel line to pop off the fuel filter. Luckily I found this at home. Took my canister off and put rubber caps on the TB's and the bike runs better than ever.

[Ken H.]

Mine got plugged and caused the fuel line to pop off the fuel filter.

Sorry, I've got to ring the BS bell on this one. There is no way a plugged fuel vapor recover canister can cause a high pressure fuel line to pop off.

[John in NC]

Not BS pal. It happened. Vacuum was so strong on fuel cap I could not open it. Once I bled off the vacuum, the bike would not start. Opened the tank and the bottom line from the fuel filter was not attached. The vacuum had crushed the inside of the fuel filter.

[ShovelStrokeEd]

Partial BS at least. The fuel line popped off because the fuel could no longer flow through the filter and the pump created sufficient pressure to cause the connection at the line to fail. That I can believe. A factory BMW filter being crushed by the vacuum sufficient to block the flow would require pressures far in excess of the simple 14.7 PSI vacuum can create. The thing will tolerate internal pressures in excess of 100 PSI without any trace of distortion. If your engine was running prior to the vacuum problem, there was 45 PSI of pressure inside the fuel filter. The numbers don't add up.

 

What I do believe happened to you was that the filter element failed and then it popped off the line due to excessive internal pressure. A vacuum sufficient to cause this would have collapsed the tank.

[Wanderer99]

I thought the cannister was a filter for in coming air as the fuel is used in the tank after venting it down by the foot peg does it take in dirt?

[T__]

I thought the cannister was a filter for in coming air as the fuel is used in the tank after venting it down by the foot peg does it take in dirt?

Andy, the evap can is filled with charcoal that catches & holds hydrocarbons that escape the fuel tank in the venting process.. When the engine is warm, & the fueling computer sees a certain set of sensor & RPM/load inputs & it opens a purge solenoid & allows the trapped fuel vapors in the evap can to flow into the TBI units & get burnt..

 

It would also act as somewhat of a filter for incoming tank vent air but that isn’t it’s intended purpose or main usage..

 

Twisty

[Ken H.]

I thought the cannister was a filter for in coming air as the fuel is used in the tank after venting it down by the foot peg does it take in dirt?

No, that is an incorrect understanding of a fuel vapor recovery system. Instead of being vented to the atmosphere and contributing to air pollution, vapors in the tank sitting above the fuel level are drawn into the canister where they are absorbed by the charcoal. Periodically they are purged by being drawn into the (left side) throttle body intake. Thus 'refreshing' the canister's charcoal to allow it to absorb more vapors.