Gas needle reads full all the time. Help please

[Brandon73fjord]

I pulled the canister out of the gas tank to see if the float was stuck. It slides up and down easily when I flip it over. Why are there 2 brown wires? I swithched the wires around thinking that they got crossed during the resto and it still read full.

[Guest Anonymous]

Connect an ohmmeter across the terminals and move the float. The resistance should change if it is working.

[Guest Anonymous]

Connect an ohmmeter across the terminals and move the float. The resistance should change if it is working.

[Jerzy]

#74 is the fuel tank sender. The other wires are Brown/Yellow (which runs from the fuel gauge to the "G" terminal on the in-tank sender) and Brown/Black (which connects to the "W" terminal and appears to be a daisy-chain ground connection for other components) -

full schematic here -

http://www.bmw2002faq.com/component/option,com_forum/Itemid,50/page,viewtopic/t,316840/

Here's some more useful info. I don't know who to credit for the Ohms test of the sender.

[Pierre]

I pulled the canister out of the gas tank to see if the float was stuck. It slides up and down easily when I flip it over. Why are there 2 brown wires? I swithched the wires around thinking that they got crossed during the resto and it still read full.

Probably a bad ground from the cluster.

Run a ground wire from the back of the cluster (there are two round nuts behind the temp gauge and fuel gauge) to any good ground on the body and see if it solves your problem.

[Guest Anonymous]

Connect an ohmmeter across the terminals and move the float. The resistance should change if it is working.

[FunkyLaneO]

Unplug both wires at the sender and see if it still reads full, if it does then the wire to the gauge is grounded somewhere.

Does it drop to empty when you shut off the car? if not then the gauge is stuck.

[Brandon73fjord]

When I unplug either/both wires it drops to empty. Also when I shu off the car the needle drops.

[pkbinplano]

Connect an ohmmeter across the terminals and move the float. The resistance should change if it is working.

[allbim]

The resistance of the fuel level sensor should be about 4 ohms when full, 73 ohms empty.

[Ray-2002tii]

Just keep the tank full all the time and it wil be right!

[FunkyLaneO]

When I unplug either/both wires it drops to empty. Also when I shu off the car the needle drops.

Then it is definitely a problem with the sender, if you unplug just one of the wires and it drops and then plug it back in and unplug the other wire and it does the same then it is receiving ground from where it is supposed to and the sender is not providing any resistance.

Test the sender like described in the other posts, it is most likely your problem.

I have a 0-100 ohm variable resistor that I plug between the wires to test the circuit. I can look through the back window and watch the gauge go up and down while I turn the knob.