Gas gauge troubleshooting

[ChevDog1]

Anyone have any tips on troubleshooting a gas gauge issue? Mine is not working after re installing the gauge cluster. It was working at one point, but quit after removing the gauge cluster. I had a bad circuit panel, so replaced it and the gauge still doesn't work. When I went to start the truck yesterday, it worked for a few minutes, then dropped back to empty. It there a common problem on these where I can start looking?

[ray_mcavoy]

Here's a good fuel gauge troubleshooting writeup in the electrical section --> http://www.67-72chevytrucks.com/vboa...d.php?t=640615 It's for 67-72 but the 73-87 gauges are pretty much the same electrically.

Since your problem started after removing the cluster and replacing the printed circuit, I'd recommend taking a close look at any connections that were disturbed during that procedure. Specifically, the terminals in the cluster plug and the "spring clip" contacts that connect the printed circuit to the studs on the back of the gauge. Make sure they didn't accidentally get bent or distorted to the point where they're no longer making good contact.

[ChevDog1]

I checked and cleaned all of those. The printed circuit was getting pretty bad at the plug connection, so I replaced the printed circuit with a brand new one.

Where is the gas gauge wire routed from the tank to the cab?

[mpierce9]

I believe it is the brown or tan colored line coming into the cab from the fuel sender to the gauge cluster plug. Search the form for "fuel sender wiring diagram"

[motornut]

A ez quick test
remove sender wire at tank should go over full,grounded out it goes to E.
you can test it like that right up to the gauge

[ChevDog1]

Is it possible to get to the sending unit wire at the tank without dropping the tank?

I'm assuming from your description above that since mine keeps showing empty, that the wire must be grounded somewhere - maybe chafed through? If it was making no connection (i.e. an issue with the plug not making contact at the printed circuit), it would show full?

[mpierce9]

Yes, The wire connects to a small nipple at the top of the sending unit (and tank) you should be able to follow the wire at the passenger side frame to the back of the truck. Unless it has been changed it is most likely a brown or tan colored wire.

[ChevDog1]

Thanks,

I'll try and check it out tonight.

[motornut]

Yes it's run in the engine harness from the front plug in.

Jimmys have that same wire with (2 nipples joined) halfway to the back,but this could be the one for the pickups with just an extension used for the Jimmys.

[conman24]

I had the same problem recently. I took the gauge cluster off. And reset the three prong gauge back in the pod. My problem was one of holders that clamp around the bolt had slipped out. Works great.

[ChevDog1]

Found it! The bozo who installed the TH400 sat the trans crossmember on top of the gas gauge sending wire. After a short time of running, it must have finally pinched through. I spliced in a new section of wire around the bad spot, and the gauge reads correctly now!

[Gregski]

Originally Posted by motornut

A ez quick test
remove sender wire at tank should go over full,grounded out it goes to E.
you can test it like that right up to the gauge

We need to have a Gold Nugget section on this Forum and this "quick test" belongs right in there, thank you so much I have a similar problem and can't wait to try this test