[sherlock9c1]

If you are having problems with just your gas gauge, it's very possible you can just remove the sending unit and fix it yourself. The sending unit can be very easily bench tested if you know a little about electronics. It's just a resistor and a wiper arm that is supposed to have 90 ohms resistance when full and zero ohms when empty.

Because of varnish buildup on the various contacts, loose connections, and a not-so-perfectly-designed resistor, these sending units end up reading high, or just plain open circuit. They are not hard to clean and if you are handy with a soldering iron, you can actually recalibrate the resistor back to zero ohms yourself.

But first things first - try a can of fuel system cleaner in the tank and see if that removes enough varnish to get your gas gauge working again.

 

[sherlock9c1]

I hope this doesn't make you feel bad, but the harness in the tank is replaceable from Napa.

 

[sherlock9c1]

Not at all, it was the connector going through the tank that was melted. I checked my local NAPA and they could not get the through harness, I am not saying it wasn't available, but they could not find it in their computer.

Oh, okay, if the yellow plastic connector and wires coming out of the round bulkhead are melted and distorted, that's a different problem entirely, and no, the Napa harness won't cover those.

Although, now that I think about it for a minute, when I put the new harness in mine, I cut the connectors off the wires and just soldered directly the wires to the bulkhead pins to eliminate them vibrating loose. Even if the pins are distorted, you might still be able to solder the wires to them and get good connections unless the wires are otherwise damaged.

Do not use shrink wrap on any wires inside a gas tank. 99% of the shrinkwrap out there is dissolved by gasoline and will just clog your fuel system.

If you didn't throw away your old sending unit, you might want to hold on to it; you might be able to sell it to someone whose sending unit rusted out.

For anyone else reading this, this is a known problem on GM B-bodies where poor connections in the sending unit cause overheating of the wires, a gas gauge that reads high and never turns your low fuel light on, and possibly fuel pump failure. Plus, these sending units are not made out of stainless steel and are prone to rusting out on top. If you have not already done so, you really ought to drop your gas tank, replace the internal harness with one from Napa, and if you can, cut the connectors off the ends of the wires and just solder the wires directly to the contacts. Then, rust-proof your sending unit by blasting off the rust and then painting and oiling the lines. New sending units are not cheap.

 

[sherlock9c1]

I soldered all of my wires because even with clean contacts and a new harness, I could watch the resistance change just by wiggling the wires with my fingers. Forget that, I whipped out the soldering gun, cut the connectors and stripped the wires, and soldered everything. Now, guarranteed zero ohm connections, gas gauge reads empty when it should, and the fuel pump never sounded so good.