Fuel Gauge Help - New sender

renjaminfrankln

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Okay need a bit of help with my fuel gauge. Has never worked since I got the truck, always remained pegged out at Full (gauge reads way past full) no matter which tank was selected.

I have done very little troubleshooting on the system, the front tank is the only one that works now (the return is clogged on the rear tank and it pressurizes and leaks when the rear is selected). Today I swapped out the front tank sender with a new one (and a new showerhead) I found the wire to the sender broken on the old pickup/sender. I was hoping that was the issue, but when I hooked it back up, sadly the fuel still reads pegged out on Full no matter which tank is selected.

Truck has an aftermarket FSV btw that I swapped out. One of the ebay ones. You can hear the FSV click when the switch on the dash is flipped, but no change in the fuel gauge reading.


Anyone have next steps for me? I know there is a lot of info out there on this subject, but I don't have time to search at the moment, got to back out in the garage and get the truck back together and clean up.
 

Shadetreemechanic

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Disconnect it from the sender and see if it stays pegged. If so you have a wire in the harness going to ground between the sender and the gauge.
The sender is a resister. Open circuit is empty. Grounded is pegged full.
 

renjaminfrankln

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Disconnect it from the sender and see if it stays pegged. If so you have a wire in the harness going to ground between the sender and the gauge.
The sender is a resister. Open circuit is empty. Grounded is pegged full.

Will do

Update: it stays pegged with the sender disconnected
 
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renjaminfrankln

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FWIW, the sender pegs out full with the sender just disconnected, the wire does not have to be grounded for that to happen.

My rear sender pegs out empty now when I switch.. perhaps that is the result if it is grounded? I haven't had a chance to fix that one yet. I will either drop the tank or pull the bed, most likely pull the bed to get to that one.

I had to pull the pickup back out due to a leak when fuel sloshed around. Turns out it was not getting even pressure from the ring. I had to mess with it and bend the tabs on the lock/seal ring to get it right. Just drove 80 miles today, no leaks.
 

Shadetreemechanic

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If its pegged with the FSV disconnected, then your issue is between the FSV and the guage, not the tank. Have you followed the wire loom back into the cab and checked for damage?
 

renjaminfrankln

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If its pegged with the FSV disconnected, then your issue is between the FSV and the guage, not the tank. Have you followed the wire loom back into the cab and checked for damage?


Sorry, I was not very clear. My front fuel sender and gauge work 100% now. The sender wire from the front tank was corroded in the wiring harness (pre fsv) and there was no connection. Someone had cut into the harness there to install a trailer connector and nicked the wire.

The gauge was reading full with a broken lead wire, not grounded out.
 
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