Fuel Gauge 1/2 equals empty?

[RedTRex]

87 cabrio - all original parts.

Fuel guage won't show lower than 1/2 tank. The fuel low light comes on. I have an extra sender which I used to to the tilt test and the guage goes from full to no lower than 1/2. The low light comes on when it should.

I have checked the nut on the back of the guage.

What else can I do/check?

[QUKBMER]

Change both senders.

[QUKBMER]

Change both senders.When this problem happens to me i change both senders and i am done.

[RedTRex]

87 Cabrio. Only has 1 sender. The one in the car and the spare both indicate the same -(no less than 1/2 tank)

[nando]

I bet you have a late model fuel gauge.

[RedTRex]

I bet you have a late model fuel gauge.

\Meaning what? it's looking for resistance from dual senders?


EDIT: I see 9/87 and later have the dual senders. Guess I need to research part numbers for fuel guages......

[nomansland92]

Same problem but my half tank is like a day left and quarter tank is empty

[scottinAZ]

if the cluster has been swapped at some point, there is likelyhood of a late model gauge in the cluster. this will indeed look for the resistance from two senders (bottom half of the gauge reads off the sender you dont have). fuel light WILL still work as normal when you are almost out of fuel. replace the fuel gauge with an early model one, and all will be right with the world again

[jlevie]

I agree that the most likely cause is that the cluster has been swapped out at some point with one from a 9/87 or later car. In which case the gauge will indicate a bit below half when the tank is empty. The fix is to remove the cluster and swap the fuel guage to the early variant used with the 55L tank.

[RedTRex]

I have learned which part number I am supposed to have.

http://www.realoem.com/bmw/showparts.do?model=1123&mospid=47309&btnr=62_0061&hg=62&fg=05&hl=38

I do have a spare of the correct (hopefully it works). I will have time to pull cluster tomorrow and see what is in it.


Look for an update tomorrow evening. Thanks for the pointers!

[bloodshot-e30]

if the cluster has been swapped at some point, there is likelyhood of a late model gauge in the cluster. this will indeed look for the resistance from two senders (bottom half of the gauge reads off the sender you dont have). fuel light WILL still work as normal when you are almost out of fuel. replace the fuel gauge with an early model one, and all will be right with the world again

what if its a 318is? it only has one sender :P

[RedTRex]

what if its a 318is? it only has one sender :P

Researching OEM, it uses the late model fuel guage and the fuel level sender that fits into pump assy. That car must have some coding built into the cluster.

[99em1]

What about the opposite problem? Fuel tank is filled but shows a tick below full

[RedTRex]

Well - the car did have the wrong fuel guage in it.

I have learned which part number I am supposed to have.

http://www.realoem.com/bmw/showparts.do?model=1123&mospid=47309&btnr=62_0061&hg=62&fg=05&hl=38

I do have a spare of the correct (hopefully it works). I will have time to pull cluster tomorrow and see what is in it.


Look for an update tomorrow evening. Thanks for the pointers!

[nando]

What about the opposite problem? Fuel tank is filled but shows a tick below full

one of the fuel senders is bad/disconnected.