Fuel Tank/ Strip issue.

Hey All,

So I thought I had a faulty fuel strip, it was registering full but the fuel went down and the strip did not register this in any major way until I unexpectedly ran out of fuel which highlighted the issue.

I have just taken the fuel strip out and the LHS of the tank was half full, I calibrated the fuel strip correctly then put back in and started the bike back up. The readout went straight back to full which I knew was not correct so I took off the pump assembly again to reveal a full LHS tank with the RHS more or less empty.

Can anyone advise of the correct functionality of the fuel transfer from RHS to LHS and if there is a possible fi for this issue or should I make the change to the fuel level float I bought a year ago but did not need to fit as I previously zapped the fuel strip? It's been working fine for over a year but then this issue.

Need to put the bike back together tomorrow for work on Monday so would hope to have it sorted by then.

Many thanks.

You might have a weak fuel pump but the fuel strip is notoriously weak and troublesome.

The fuel strip is great idea spoiled by a very (VERY) poor design. It has three layers of mylar plastic with a coarse copper zigzag printed between layers 1&2 and a fine copper track between layers 2&3. The coarse track heats the strip which changes the resistance of the fine track. Petrol in the tank chills the strip so the heated resistance changes according to fuel level. The rub is that nobody considered thermal expansion of plastic compared to copper. Sooner or later the fine copper strip will crack and the fuel level shows all sorts of rubbish. Who knows why the engineers did not simply take the resistance value from the heater track.

Due to emissions rules, fuel heating, etc, the fuel pump is run just hard enough to feed the injector rail with next to no return fuel flow. At about 25% remaining in the tank, the ECU changes the pump duty cycle so that more fuel is returned to the tank. This excess flow drives a venturi pump ("sucking jet pump" in BMW speak) which lifts fuel from the tank right hand side so the bike can use all 35 litres.

Problem 2 is that a broken fuel strip either prevents the pump from powering up (tank level is reading high) or if it reads constantly empty the pump is run too hard and wears out more rapidly.

The fuel strip can be zapped with a gas piezo lighter between pins 2 and 3 on the level gauge plug on top of fuel pump. There is no external spark, but the spark made within the strip will create a conductive connection across the cracked copper track. There is much info on the subject. It's not a permanent fix and sooner or later the strip will fail completely.

You can fit resistors to the cable connector above the fuel pump to Spoof a full or empty fuel tank signal.

You can get a converter circuit to allow a normal float gauge to output a level signal the ECU can use. Again, there are threads on the subject.

Another fix would be to put a second fuel pump on the tank RHS with a switch to pump fuel across when you get near the driven range that would run out with the LHS dry.

Or just get it replaced and have it warrantied for 2 years.

Sent from a U11

Just to put a spanner in bendys theory.
My seventh fuel strip is playing up a bit. It's been in for 20 months
My fuel guage Is showing about 3 quarters full after covering about 320 miles. The range is also saying I have 300 miles still left in my tank.
I put in 36.39 litres the first time I filled it with over 200 miles still showing on my range. The second time yesterday was the 320 miles figure with 300 still left in my range. I put in 30.59 litres this time.
So it would appear that even though my guage says I have a lot left In the tank and the range says the same I can still use the full tank of fuel without any problems with the pump not using the right side of the tank.
I shall be paying for another fuel strip to be fitted soon. I need a working guage and accurate range. I had four strips fitted for the price of one last time. 50 quid a strip doesn't sound so bad.

gazza12adv said:

Just to put a spanner in bendys theory.
My seventh fuel strip is playing up a bit. It's been in for 20 months
My fuel guage Is showing about 3 quarters full after covering about 320 miles. The range is also saying I have 300 miles still left in my tank.
I put in 36.39 litres the first time I filled it with over 200 miles still showing on my range. The second time yesterday was the 320 miles figure with 300 still left in my range. I put in 30.59 litres this time.
So it would appear that even though my guage says I have a lot left In the tank and the range says the same I can still use the full tank of fuel without any problems with the pump not using the right side of the tank.
I shall be paying for another fuel strip to be fitted soon. I need a working guage and accurate range. I had four strips fitted for the price of one last time. 50 quid a strip doesn't sound so bad.

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Mine is acting up, so I would say failure is inevitable.

My 12 year old bike will be going to the main dealer for a new expensive warrantied part.....for the above reason.

Sent from a U11

Pal is on his sixth? He has lost count. Dealers /BMW are repacing them on warranty sine die according to his dealer.

Great thanks all, so a trip to the dealer for a warrantied part it is then..I take it the two years is standard at BMW dealers and they don't try to wriggle out of replacing them foc?

commandoallan said:

Great thanks all, so a trip to the dealer for a warrantied part it is then..I take it the two years is standard at BMW dealers and they don't try to wriggle out of replacing them foc?

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I didn't have a problem getting mine replaced under the 2 year warranty. My last one was fitted just a month before the 2 years was up. He said if it failed soon after the warranty expired they would still consider a goodwill fix. It has now lasted 20 months so I suspect I will be paying again.

gazza12adv said:

I didn't have a problem getting mine replaced under the 2 year warranty. My last one was fitted just a month before the 2 years was up. He said if it failed soon after the warranty expired they would still consider a goodwill fix. It has now lasted 20 months so I suspect I will be paying again.

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I think mine is on the way out (2008) what is the dealer replacement charge?

Just fixed the strip with piezo zap on a 2007 GSA worked a treat cost £5.75 lol

Big Si said:

I think mine is on the way out (2008) what is the dealer replacement charge?

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Just had to pay for another. It has gone up to around £230.00 now from about £210 4 year's ago

gazza12adv said:

Just had to pay for another. It has gone up to around £230.00 now from about £210 4 year's ago

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Thanks, at least I'll have 2 years without having to worry about it!

Edit: filled up today, and it's started working again !

My 2010 R1200GSA fuel sensor failed recently, 35,000kms and 25 months after new one was fitted. I paid for the last one, which has now failed.

Replaced today by Joe Duffy under goodwill, quick and painless. (If I was having to pay, I would go the float-sensor route....)

First sensor lasted 80K kms, 70K kms of which was in Saudi Arabia, and lasted only 10K kms after imported to Ireland. As I said, new one lasted 35K kms.