fuel gauge problem driving me nuts

[thom]

I bought a fuel gauge kit from NAPA that includes the gauge and sending unit as well as the mounting under dash bracket. It worked for about 3 weeks then the needle fell to below EMPTY and stayed there. They gave me a new gauge but that didn't fix it. After some more checking I figured the problem must be in the sending unit. I replaced the sending unit and that didn't fix it either. I checked the wire from the tank to the gauge and it burned the test light but not full brightness so I figured the new gauge must be bad, so I tried another gauge. Still not working. However, when hooking the volt meter to the wire at the gauge it reads the same as when hooked to the sending unit on the workbench, with the sender at 3/4 full, which is what the tank has. I'm puzzled. It sees that all the parts work correctly on the workbench but not on the truck.

 

[Blue Eyed Devil]

Sounds like a ground issue.

 

[dutch]

ground strap between tank and fuel line to bridge the rubber hose?

 

[sneakysnake]

What they said, run a ground to the sending unit.

 

[thom]

I have a ground strap from one of the sender mounting screws to the frame because the tank is a plastic one from a Ford Ranger.

 

[Skip]

Check continuity on ground wire. Both ends of the wire, and from the sender to the frame. There could be a bad connection on either or both ends.

Check the resistance on the gauge while slowly moving it through the range of motion. That is the signal that the sender is sending to the gauge.

 

[thom]

I hope that I can get to the wire connection at the sender without dropping the tank. If so I plan to replace the wire from the sender to the gauge tomorrow, although I get what appears to be the right reading at the gauge. I replaced the "hot" wire from the ignition switch to the gauge today.[S

 

[thom]

I can get to the connection without dropping the tank. I found the wire almost broken at the tank connection so I replaced the end. The gauge read again, but not correctly.Then I discovered that my taillights and taglight were not working. The front half of the wire going back to the taillights and taglight was fried. Since it ran alongside, and touching the tank sender wire I replaced both. Now both problems seem to be fixed. During the testing/trouble shooting I ran a new temporary wire from sender to gauge and that didn't fix it. I don't understand why but I'm glad it's fixed.[cl

 

[sneakysnake]

Is the float free of obstructions in the tank, sides,baffles,foam stuff like that? Is the float dry inside?