willysmjeeps.com

My fuel gauge has been working perfectly. Today, when I started the jeep, it registered about 1/4 tank. After a short spell of driving the needle started bouncing around the full mark. I stopped and added fuel and turned on the ignition and the gauge registered about 3/4 for about the amount of gas I added, and held steady at that. When I started the car, the needle again started bouncing at the full mark. Without engine running the guage accurately reads and is steady, but when engine running it again bounces to full. With racing the engine there is a little bounce on the needle at the full mark.
Jiggling wires on gauge has had no effect.
Any suggestions?
Thanks
Mike D

Step one: Check all connections. Don't just shake & jiggle. Open and inspect! Pay close attention to the wire contact with the metal connector housings.

Step two: check grounds. Try connecting a jumper wire between the gauge cluster and the firewall and a jumper wire between the gas tank and the firewall. It helps to have a good quality digital VOM here and check actual resistance between both the tank and instrument cluster and their grounds.

Step three: Follow the Army instrument troubleshooting guide in our downloads section.
http://www.willysmjeeps.com/v2/modules. ... tit&lid=46

Remember that a short = empty gauge reading.
Open circuit = full gauge reading.

Thank you

Check your sender float! Make sure it's not full of gas like mine was. John

John, I wouldn't point him that way. He says it is reading full most of the time now when it's at 3/4 or better in the tank. Heavy float would read empty or almost empty all the time.

Correct Wes! Just was telling him while in there if his is plastic, to check it. It might save another trip back into the tank. I ran a extra ground wire fromthe sender screw to the rear seat mount bolt. With paint and rubber etc. the tank will not ground well. John

The guage reads correctly when ignition is on. Only moves to full when the engine is running. So I assume the float, etc are correct for reading, and probably a ground condition when engine is running but seems strange that the ground must be OK if it reads correctly with power thru it not with engine. I will check all connections and add a supplementary ground wire and see what happens.
thanks Guys
Mike D