Replacing the fuel strip sensor with a used one

[RoSPA_man]

I've got a used fuel strip sensor on the way to me and will be fitting it in the next few days.

 

I Googled and found the description (quoted below FYI) and just wondered whether that applies only to a brand new strip i.e. could I skip the calibration steps because it is used? I'm not obsessed about it being ultra-accurate anyway; I'm primarily fitting it to resolve the "no gas" warnings I am getting - the flashing gas pump and the yellow warning triangle illuminated !

 

 

FROM BMWMOA

Fuel sensor replacement IS NOT a DIY operation because it requires the BMW diagnostic computer to calibrate the new sensor. Summary procedure below, condensed to omit various stuff like pulling the tupperware and all the std precautions about working with fuel tanks. Reference is 16 14 000 on the RepROM disc.

 

1) Drain and remove fuel tank.

2) Remove fuel pump unit from tank.

3) Lift filler neck, disengage fuel sensor and lift it out of tank.

4) Because new sensor has to be calibrated DRY, connect sensor to fuel pump while pump is removed from tank.

5) Reconnect fuel pump to bike electrics while the pump is still removed from the tank.

6) NOTE: Battery must be fully charged and bike connected to charger while calibrating. Procedure will abort or misfire if voltage drops below 12.6 V

7) Start BMW diagnostic system, initiate CIP program, and follow its instructions to calibrate. Disconnect diagnostic system, then charger when done.

8) Install fuel level sensor in tank. Reassemble everything.

 

[dirtrider]

Afternoon Hugh

 

You don’t have to remove the gas tank, in fact you don’t even have to drain it if it is around ¼ tank or lower.

 

As to that calibration? -- maybe & maybe not. It sure won’t be accurate if not calibrated to your tank & electronics but it might work enough to keep the light off. You are actually calibrating YOUR bike’s electronics to the new/used fuel strip as the strip itself has nothing to calibrate.

 

Have you talked to your dealer about your failed fuel strip. BMW (at least in USA here)has kind of a super secret head nod to the dealers to replace those strips even in out of warranty situations. If your dealer won’t then he is trying to squeeze you instead of helping you. If your dealer won’t help then ask him to get BMW involved (with you present) so the dealer can’t lie to you about what BMW said.

 

Before replacing your strip try unplugging the connector from the top of your fuel pump assembly (the fuel gauge one not the pump one). Then clean the terminals & make sure they are making good contact. If it still acts up then try removing your strip, cleaning the connector terminals inside the tank, then snap the plastic covering open on your fuel strip, remove the strip & clean the strip with a soft cloth & Techron. Then re-connect & try it. I just did this to a friend on mine’s 1200RT & the strip started working again.

 

 

 

[RoSPA_man]

Afternoon Hugh

 

You don’t have to remove the gas tank, in fact you don’t even have to drain it if it is around ¼ tank or lower.

 

As to that calibration? -- maybe & maybe not. It sure won’t be accurate if not calibrated to your tank & electronics but it might work enough to keep the light off. You are actually calibrating YOUR bike’s electronics to the new/used fuel strip as the strip itself has nothing to calibrate.

 

Have you talked to your dealer about your failed fuel strip. BMW (at least in USA here)has kind of a super secret head nod to the dealers to replace those strips even in out of warranty situations. If your dealer won’t then he is trying to squeeze you instead of helping you. If your dealer won’t help then ask him to get BMW involved (with you present) so the dealer can’t lie to you about what BMW said.

 

Before replacing your strip try unplugging the connector from the top of your fuel pump assembly (the fuel gauge one not the pump one). Then clean the terminals & make sure they are making good contact. If it still acts up then try removing your strip, cleaning the connector terminals inside the tank, then snap the plastic covering open on your fuel strip, remove the strip & clean the strip with a soft cloth & Techron. Then re-connect & try it. I just did this to a friend on mine’s 1200RT & the strip started working again.

 

 

 

Thanks as always DirtRider.

I have in fact already done the clean up of leads and connectors etc on the outside - no change obviously- but I will follow your advice on trying to refurb the existing strip first (I have a used replacement on the way to me). I'll let you know what happens.

BTW, I try not to bother my dealer much as I feel he doesn't bother!

 

 

[dirtrider]

Morning Hugh

 

A couple of things I should have mentioned on that fuel strip replacement.

 

If you plan of removing the fuel pump assembly to look at it or work on it that will require disconnecting the water drain line that passes through the fuel pump plate assembly. Seeing as that hose has a loop in it there is usually some water trapped in that hose so I suggest you blow some air through the drain hole (in the fuel fill ring) to blow all the water out before working on the system. Otherwise that water will end up in the fuel tank.

 

Also that fuel strip sits in molded in socket in the very bottom of the fuel tank so use a (non sparking) light (torch to you) to look in the tank & make sure that fuel strip is seated in that socket correctly as you lower the upper plate (with the fuel strip clipped to it) down into place.

 

[EddyQ]

As to that calibration? -- maybe & maybe not. It sure won’t be accurate if not calibrated to your tank & electronics but it might work enough to keep the light off. You are actually calibrating YOUR bike’s electronics to the new/used fuel strip as the strip itself has nothing to calibrate.

 

Well, I figure there are two things that vary and require calibration. The first is the tank shape and it likely is different from bike to bike and needs calibration to take out those differences. But, the tank shape is not the thing that is changing here, so that part of the calibration should be still good. The second part of the calibration is to remove errors in the strip. So, what kind of errors are likely?

If I were to bet, the mechanical size is close enough to not change a thing. But the resistance and the change of resistance with level is likely to change from one to the next. If you don't adjust for it, I bet there will be an offset and/or gain error. For example, the gauge might read 1/4 tank when it is empty and 7/8 when full. Or below empty when empty and half full when full. Now, I am just speculating here. I have no knowledge that this is in fact true.

 

If this true, I'm wondering if one could add a potentiometer to alter the resistance and recover accuracy? Interesting. I'd be interested in how this works out.

[dirtrider]

Afternoon EddyQ

 

 

That fuel sensor strip is way more complex than a simple resistor. The strip is actually heated with one set of inputs while the output is a Wheatstone bridge type.

 

That sensor is also way up in the 2-3K range but because of the strip heating & fuel level cooling doesn’t seem to be a linear change so adding a fixed (or adjustable) resistance probably wouldn’t allow tuning.

 

 

[RoSPA_man]

Morning Hugh

 

A couple of things I should have mentioned on that fuel strip replacement.

 

If you plan of removing the fuel pump assembly to look at it or work on it that will require disconnecting the water drain line that passes through the fuel pump plate assembly. Seeing as that hose has a loop in it there is usually some water trapped in that hose so I suggest you blow some air through the drain hole (in the fuel fill ring) to blow all the water out before working on the system. Otherwise that water will end up in the fuel tank.

 

Also that fuel strip sits in molded in socket in the very bottom of the fuel tank so use a (non sparking) light (torch to you) to look in the tank & make sure that fuel strip is seated in that socket correctly as you lower the upper plate (with the fuel strip clipped to it) down into place.

 

I have the new (to me) sensor which arrived today. I won't get to doing the job until the weekend at the earliest, but one question I gotta ask, having reviewed the BMW Service CD and without the Tupperware off so I can't examine it right now.

 

The Service CD mentions a BMW Tool for opening the "union nut". That seems to be the outer edge of the fuel pump - what can I use to loosen this - an oil filter strap maybe? Does it unscrew by multiple revolutions or does it just turn through like 45 degrees etc.?

 

Apologies for what seems like a lazy question but I want to get the tools I need lined up in advance.

 

[EddyQ]

That sensor is also way up in the 2-3K range but because of the strip heating & fuel level cooling doesn’t seem to be a linear change so adding a fixed (or adjustable) resistance probably wouldn’t allow tuning.

 

Well, you may be right DR. You usually are.

 

But, a circuit that both heats the strip and then measures its resistance (where resistance should be proportional to length of heated section plus cooled section), I would think that would be rather linear. For instance, the strip may have a resistance of 2K when 100% of its length is hot and 3K when 100% of its length is cold. I would expect the resistance to be 2.5K when 50% heated. Although, it is quite possible that the heating is not done with a source of current, but rather a source of voltage and then it would be not linear since the amount of heating would change with % cooled. m m m.. This is yet another interesting circuit worth fiddling with on this bike.

[BrianV]

 

I have the new (to me) sensor which arrived today. I won't get to doing the job until the weekend at the earliest, but one question I gotta ask, having reviewed the BMW Service CD and without the Tupperware off so I can't examine it right now.

 

The Service CD mentions a BMW Tool for opening the "union nut". That seems to be the outer edge of the fuel pump - what can I use to loosen this - an oil filter strap maybe? Does it unscrew by multiple revolutions or does it just turn through like 45 degrees etc.?

 

Apologies for what seems like a lazy question but I want to get the tools I need lined up in advance.

 

You can easily rotate the outer ring (union nut) with a tap or 2 in a CCW direction on a couple of the tabs with a small plastic headed mallet - just enough to loosen it so you can spin it off with your hands. NO METAL HERE !!! (sparks) It doesn't have to spin very far if I recall correctly. You will know when it's loose.

 

-Brian

 

[RoSPA_man]

Morning Hugh

 

A couple of things I should have mentioned on that fuel strip replacement.

 

If you plan of removing the fuel pump assembly to look at it or work on it that will require disconnecting the water drain line that passes through the fuel pump plate assembly. Seeing as that hose has a loop in it there is usually some water trapped in that hose so I suggest you blow some air through the drain hole (in the fuel fill ring) to blow all the water out before working on the system. Otherwise that water will end up in the fuel tank.

 

Also that fuel strip sits in molded in socket in the very bottom of the fuel tank so use a (non sparking) light (torch to you) to look in the tank & make sure that fuel strip is seated in that socket correctly as you lower the upper plate (with the fuel strip clipped to it) down into place.

 

 

Half way through – here’s the update

 

This is a bit of an annoying job - not difficult but a bit fiddly and “non-wrenchy” - but I’m getting there. Also, you can’t test results easily as you need to ride the bike to check if the gauge wants to reset and work

 

Anyway….

 

I got the old sensor out, did what you suggested – I dismantled the strip, cleaned it (although it was already sparkling) with Redex and cleaned the junction box on the top of the sensor as well, cleaned all connections etc., refitted, but no change.

I fitted the new (to me) sensor and was about to give up on that too when it sprang into action! It’s registering a reading - looks about right for the amount of fuel I think is in there- and the lights are gone out at least. I now need to check my work and button it all up, then fill up and see how accurate (or not) the new strip is in uncalibrated mode. If it keeps the yellow light off for 200 miles or so, I’ll be happy and will not bother my dealer with my money to calibrate.

 

Question:

Should the fuel pump assembly clip satisfactorily back down into position in the tank or does it sort of sit proud a bit and need to be “squashed” into a sealing position by tightening the “union nut”?

 

 

[RoSPA_man]

Guys

I have now decided to back up a little and to do the job properly! I drained the tank (left side anyway) and fully removed the fuel pump assy. to provide access and a view!

 

What I am bothered about is that as I lower the sensor into position (in the left side), the only "catch point" for the clip on the end of the sensor seems to be a (wider than I expected) "mound" on the floor of the tank around which the clip thingie will fit, but it is not convincing. I have looked and felt all around in there and there is nowhere else it would seem. I was expecting a more definitive and accurate fit - am I right or doing something really silly?

 

I believe I am right in saying that the water drain hole on the filler neck is at 9 o'clock as seen from seated in the saddle - that dictates how the sensor hangs. For the record, he sensor is hung so that the wires are nearest the pump assembly.

 

Thanks in advance

[dirtrider]

[RoSPA_man]

 

 

Hi DR

Thanks for the reply but my question related to the fuel level sensor as it hangs in the tank and the orientation of the filler neck, not the fuel pump assembly.

Many thanks

Hugh

[dirtrider]

[RoSPA_man]

DR (the most helpful Ohian)

Thanks a lot. That photo solved it all - the sensor hangs on that ring counter to logic- the ring actually sort of jams it in position (there are tiny marks on the sensor to confirm it - and by reversing it on the ring as per the photo, it now lines up naturally into the scalloped out area on the floor of the tank. All the usual things were telling me to hang it the other way around - I should also have noted the orientation while taking it apart - lessons learned!

 

I'm now enjoying this job at last!Only delayed waiting for friggin' hoseclips for the water drain tube!

 

Funny that my Service CD and the Haynes manual both describe a float-type sensor (must have been used in the early models); that didn't help!

 

Speaking of which where can I get a later CD like you obviously have - I can't remember where I got the current one?

 

 

 

 

[RoSPA_man]

Quick update on my newly fitted, used and uncalibrated fuel sensor.

 

1. Start situation: I had at least 5 litres of fuel in the tank when I buttoned it all up today. Display showed a small amount of fuel (Yo!), but I had a flashing petrol pump and the yellow warning triangle and a message saying “<----18 miles”.

 

2. As I rode the first mile, that rapidly dropped to “<--12 miles” but it then steadied and read a reducing range so that, 13 miles later, before I filled up, it had dropped to “< ------2 miles”. So the first thing is that, if the gauge is consistent, when I next see that 2 mile warning, it will hopefully really mean I have 5 litres less the amount used to go 15 miles approx. = 3.5 litres left

 

3. Oddly, I had the ignition on while fuelling (to reset trip)and the first thing I noted was that I was registering ¼ tank – I thought that it was impossible for the gauge to change without the bike moving a mile or so?

 

4. Anyway, a mile after the fill-up, all the warnings are off and the gauge was reading about ¾ full- which I assumed was as good as it would get. However, it gradually improved and now seems to be reading about “correctly” ie almost full after about 30 miles since the fill.

 

Now I just got to see what happens as I do miles tomorrow – and crucially what it shows around the 200 mile mark and beyond!

 

[bikerboy108]

Can anyone else verify if Dealers will replace fuel sensor if out of warranty 3months but has only 9,000 miles on it??

[dirtrider]

Can anyone else verify if Dealers will replace fuel sensor if out of warranty 3months but has only 9,000 miles on it??

 

Afternoon bikerboy108

 

That seems to depend on your particular dealer. Some will replace out of warranty & some try to squeeze the customer for every last cent in their pocket.

 

According to a friend of mine that works at a BMW dealer they have been given the OK by BMW to take care of failed fuel strips on out of warranty bikes. As a rule they have been doing that, but how your dealer treats you is kind of a crap shoot.

 

 

 

[David Vale]

My (UK) dealer arranged that BMW would replace the part if I paid for labour. In the event, the dealer charged less than anticipated for labour, so I was happy enough.

 

I was out of warranty 3-4 montyhs and had almost 20k miles on the clock.