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Replaced spark plugs on the 712 the other day. While I had the engine cover off I decided to clean up the mollenek (sp) connector.

Mind you gas guage was working fine up to this point. I sprayed both sides of the connector with contact cleaner and let the crude ooze out. While I am doing this I notice that in the wiring harness not all the wires went to the connector, there is a seperate wire, which looks like it has a fused link or fuse in it which comes from the harness and goes into the engine cover or possibly the engine.

Turned on the Pinz and no fuel showing on the guage. Stopped motor, redid the connector, closed it up, starte motor still no fuel guage.

Started wiggling wires from the harness to the mollenck and also the one that looks like it has a fuse in it. All of a sudden fuel guage comes on, spikes and settles at about 1/2 tank where it was before things started.

Changed oil and filters today, turned the truck on and no fuel guage.

What does that wire do? Where does it come from and where does it go? No circuit breakers were tripped by the way.

Any help would be appreciated. Thanks,

Andy

Andy,

I'm not really sure which wire you're referring to. But here's my understanding of the fuel gauge circuit: 24v is supplied to the gauge (not the 24v for the light), and then runs from the gauge to the sender, where it grounds out based on fuel level. To check the gauge, you ground the line going to the sender - the gauge should peg. I'm not aware that this circuit goes through the molex plug on the engine.

It sounds to me like you've got loose wires. I'd begin by checking the connections on the back of the gauge and the connection/s at the sender. While you're at the sender, you could install a ground wire, as a poor ground through the tank can cause problems like gauge inaccuracy.

Right now, I've got a loose connector on the gauge, and my gauge is operating sporadically. That's today's project, or one of em...

You are probably correct, but everything was fine with the guage until I cleaned up the molex. Haven't been behind the dash. Truck was just sitting, no reason for anything at the sending unit to go bad.

Gotta use a regular truck to feed today, will pull dash later. Thnx

Andy