Fuel gauge not doing what it should

Post Tue Apr 10, 2012 8:16 pm

Hi folks. My fuel gauge seems to be sitting in the wrong place and won't shift. I have changed the sender with the float in it for a working unit but it still playing up. The low level light still comes on. When I disconnected the sender the needle fully deflects.

Does this confirm that the gauge is faulty of could there be something else.

Also, will I need to change the whole instrument panel or can the fuel gauge be changed on it's own?

Post Tue Apr 10, 2012 8:20 pm

What size tank do you have? For Instance If you have a 63 Litre Tank, & put a 55 Gauge/Sender with it, it'll give a false reading, Its happened to me!

Post Tue Apr 10, 2012 8:20 pm

*sigh*

http://www.e30zone.net/e30zonewiki/inde ... Fuel_Gauge

Post Tue Apr 10, 2012 8:22 pm

There was also a 58 Litre Tank, Mr.Machine. IIRC they in very early cars.

Post Tue Apr 10, 2012 8:54 pm

Do the senders have part numbers on them? I'll need to compare the two and see which one I have. Sounds like I might have two of the wrong type though!

Post Tue Apr 10, 2012 9:00 pm

I'm not Sure, Someone will know.

Post Tue Apr 10, 2012 9:00 pm

The sender unit that goes into the pump is the same for 55L and 63L models. The incompatibility is trying to use a 55L fuel gauge with a 63L tank setup (with the two senders), and vice versa. It's no individual fault of the components.

Post Tue Apr 10, 2012 9:07 pm

Ok, so there is a chance someone has swapped the cluster in my car. Wouldn't be surprised to be honest, everything on this car has been a half hearted effort so far.

So if the senders are the same I need to find a fuel gauge to match my tank. How can I find out for sure what size tank I have if the cluster has been changed. Preferably without draining the tank and filling it up before some smart arse says it.

Post Tue Apr 10, 2012 9:09 pm

What car is it?

Post Tue Apr 10, 2012 9:33 pm

What happens when you bridge the wires to the senders, as detailed in the Wiki?

Post Thu Apr 12, 2012 9:42 am

OK, it's a 1987 325i cabriolet. As far as I can see, under the rear seat there is only one sender. Does this indicate the smaller tank?

Post Thu Apr 12, 2012 9:48 am

The most obvious difference between the two tanks, which can be checked without any dismantling at all, is that the 55 litre tank has a S shaped pipe of around 12mm diameter joining together the two haves of the tank at the bottom, at the rear.
No such pipe on the larger tank.

Post Thu Apr 12, 2012 12:01 pm

Ok, have done a bit of investigation now. I have taken the instrument cluster apart and the serial number (1381 884) on the fuel guage for a 60L tank and according to realOEM my car should have the one for a 55L tank. Serial number 3374 824.

So another big thanks to whatever previous owner put in the wrong cluster along with all the other cowboy fixes he has left me scratching my head over.

And a huge genuine thanks to everyone helping me solve these problems, thank goodness for this forum.