Gas Tank problem - how to troubleshoot????

[82gmc]

My Truck: 1982 GMC serria with 6.2L.

This problem just happened. My RH tank works fine. When I switch to LH (full tank) gauge drops to empty and no gas (possibly not enough????).

If I switch to the LH tank with ignition on, but engine not running, the fuel gauge goes to full. I start the truck, fuel gauge drops to empty and I have to switch back to the RH Tank for gas.

I replaced the tank switch in the cab.

Any ideas as to where to start????? What to look at???

Thanks

[allformike]

i'm not shure about the gauge ? but for the not running, it could be that the tank's fuel filter could be plugged or if you live somewhere that freezes a lot, like me and the wonder state of michigan, the fuel could be gummed if the tank hasn't been used, then you should put some additive in it. i hope this gives you a idea, but once the others read this, they should know what to do.

[DmaxMaverick]

I'd suspect the tank switching valve. Not too uncommon. Check your wire connections and grounds thoroughly. Could also be the tank sender/pickup assy. Try switching the tank sender wires at the valve, and if the problem is the same, it's the valve. If the problem follows the wires, it's the sender.

[82gmc]

Thanks for the help. I will try switching the wires at the value. The truck runs fine on the one tank.

I have another question aqbout the fuel gauge. What makes the guage roll over when full, bounce around in the middle and settle down when near empty? The guage or the senders????

[DmaxMaverick]

Dual tanks are a piece of cake to diagnose. If both tanks fluctuate, it's the gage. If only one, it's the sender. It could be the wire harness, but doesn't sound like it. Too consistent.

[82gmc]

Sending Unit is bad....Where to buy?????? Anyone have a good they want to sell?

[66stingray]

Try GasTanks.com $70 for sender.

[82gmc]

Thank you LH side is even a couple bucks cheaper.