Gas Gauge Off The Deep End

[Ronno6]

1984 C10 dual tanks.
New tanks, at least 1 new pickup/sender.
Just installed gauge cluster after 2+ years.
Gas gauge travels WAY past full...........same for both tanks.
Maybe 5 gal in each tank.
Tank selector switch and valve working.
Sound like a ground issue??
Both tanks at the same time??

Gotta fix before I re-install the steps...

 

[bucket]

It sounds like maybe the sender wire circuit is shorted to ground, at some point between the cluster and the tank switch.

 

[Camar068]

1984 C10 dual tanks.
New tanks, at least 1 new pickup/sender.
Just installed gauge cluster after 2+ years.
Gas gauge travels WAY past full...........same for both tanks.
Maybe 5 gal in each tank.
Tank selector switch and valve working.
Sound like a ground issue??
Both tanks at the same time??

Gotta fix before I re-install the steps...

when you've got the cluster out, run a wire directly to it and see what it reads. I used speaker wire and gator clips I had laying around to troubleshoot it.

 

[PrairieDrifter]

They'll peg out in my orange truck if the sender wire isn't tight and making good connection at the sender.

 

[bucket]

They'll peg out in my orange truck if the sender wire isn't tight and making good connection at the sender.

Iirc, poor connection (ground or signal) will cause the gauge to peg on empty. If the sender wire is grounded, it will peg on full. Unless I have that backwards...

 

[PrairieDrifter]

Iirc, poor connection (ground or signal) will cause the gauge to peg on empty. If the sender wire is grounded, it will peg on full. Unless I have that backwards...

Mine is pegging full. But I have either a bad switch or switch valve, so that may be my cause. Dual tanks.

But mine is for sure doing it when the sender wire doesn't have proper connection, on both tanks too, otherwise when properly contacting the gauges work fine, so I think my switch is good.

I thought fuel gauges pegged way over full with an "open" circuit. Not plugged in or grounded. Like the oil pressure gauge? I think? Maybe oil pressure pegs if grounded, I can't remember right now lol

 

[bucket]

Mine is pegging full. But I have either a bad switch or switch valve, so that may be my cause. Dual tanks.

But mine is for sure doing it when the sender wire doesn't have proper connection, on both tanks too, otherwise when properly contacting the gauges work fine, so I think my switch is good.

I thought fuel gauges pegged way over full with an "open" circuit. Not plugged in or grounded. Like the oil pressure gauge? I think? Maybe oil pressure pegs if grounded, I can't remember right now lol

I'm betting I was remembering it backwards.

 

[ali_c20]

Good videos for gas gauge troubleshooting:

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[Jgonick]

If anything lowers the flow of current the needle moves towards Full. (or 3 O'clock with no current)
so possibly a bad connection with sensing wire (pink) or bad ground. If both tanks are doing it- I would start by checking the pink wire connection at the fuel selector valve & firewall (bulkhead) & back of gauge (make sure nuts are tight)

Another great video

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