petrol guage problems..

Wed Jun 29, 2011 8:58 pm

hi guys,

wonder if any of you can help..

the petrol guage in my 1990 325i sport is faulty.. no matter how much fuel is in the tank full/empty, the needle flickers all over the place.
the petrol liamp works- i use this as my judge for when to re-fuel, but i would like to have it working properly again.

what part(s) should i be looking for to replace?

many thanks

Thu Jun 30, 2011 12:45 am

There are two level senders for the tank, one under each inspection cover under the rear seat. Unplug one at a time and short together the wires of the plug when there is less than half a tank of fuel on board. This will give an incorrect reading, but hopefully a steady one when the faulty sender is shorted.
Another possibility is a loose or missing nut on the back of the instrument cluster, directly behind the fuel gauge.

Thu Jun 30, 2011 10:46 am

thank you.. i'll have a look.

Sun Nov 13, 2011 8:09 pm

I tried the nut on mine and it stopped it flicking around - now its just fixed at 3/4 full. Stays the same till the red light comes on. Any ideas if this is one or both of the senders or something else?

Cheers!

Sun Nov 13, 2011 8:27 pm

bpowell555 wrote:I tried the nut on mine and it stopped it flicking around - now its just fixed at 3/4 full. Stays the same till the red light comes on. Any ideas if this is one or both of the senders or something else?

Cheers!

Pull the three pin plug off of the fuel pump assembly, and see if the gauge drops to zero.

Sun Nov 13, 2011 8:30 pm

Ok, if I do that what then?

Cheers Brian.

Sun Nov 13, 2011 8:56 pm

Report back!

Sun Nov 13, 2011 10:38 pm

when my tank is half full the gauge fills up and emptys depending on which corner i have just gone round and how fast

Mon Nov 14, 2011 12:10 am

parkin10 wrote:when my tank is half full the gauge fills up and emptys depending on which corner i have just gone round and how fast

That sounds like a four pot saloon tank. The six pot/touring tank is much more sophisticated, and doesn't suffer from this.

Mon Nov 14, 2011 12:31 pm

Ok off with the carpet again!

Mon Nov 14, 2011 8:58 pm

Brianmoooore wrote:
parkin10 wrote:when my tank is half full the gauge fills up and emptys depending on which corner i have just gone round and how fast
That sounds like a four pot saloon tank. The six pot/touring tank is much more sophisticated, and doesn't suffer from this.

i am sure it the correct 6pot tank
i only ever let it get to 1/4 empty which it will take a good £65 to fill it back up---dosent last long

i popped the tank off last year to change the breather pipe there are two plastic pips that run over the top of the tank from one side to the other i presume these are balance pipes
i found the breather pipe a swine to push down the tube from the inner wheel arch to the tank

Mon Nov 14, 2011 11:20 pm

One of the small plastic pipes is a vent from the top of the LH side of the tank, and the other is the vent to the atmosphere (or engine via carbon canister) going to the front of the car.
The fuel transfer pipe is hidden inside a 62 litre tank, but is visible on a 55 litre tank as a curved pipe of around 12mm diameter linking both halves of the tank at the bottom of the back of the tank, running under the propshaft.