Fuel gauge issue

[Trucky250]

Hello Everyone,

My fuel gauge is not working properly, the other gauges on the dash are working like they should.

I believe i have read most of the topics concerning fuel gauges not working properly but i havent found one with the same problem
when I don't have the key in the ignition the gauge is almost on empty, just a little bit above.
when I put the key in the ignition and turn it the gauge goes up to just a little shy of one quart, i have 2 fuel thanks and it doesn't matter which tank i select (front or rear) the gauge goes up to the exact same level for both thanks.
the gauge should be reading full for both tanks.

could anyone give me some advice on where to look and how?

thank you!

[Gary Lewis]

Nick - As said in your introduction post, check out the Troubleshooting tab on our page at Documentation/Electrical/Gauges.

But fuel gauge sending units are notorious for going bad.  So many of us have had problems.

To your specific observations, the gauges don't show anything meaningful when the key is off.  As explained on the Troubleshooting tab, the gauges are actually thermometers and have a heating element below them.  So what they show with the key off is more related to the inside temperature of the truck than anything else, but a fuel gauge will usually show below Empty a few minutes after the key is turned off.

So if yours shows above Empty then the gauge may be bad.  And if it goes to the same place for either tank with the key on that might also suggest it is bad.  But the real test is, as suggested on the Troubleshooting tab, to pull the wire off the sending unit and ground it to the frame.  Then get in the truck and turn the key to On. In a few seconds, as the gauge heats up, it should read above Full.

Don't leave the key on too long as it might hurt the gauge, but you can flip the tank switch to the other tank and if its wire isn't grounded it should slowly drop back to read whatever level is in the tank, which you said is Full.