pimpimusmaximus

Looking for the gas tank sending wires on my 84 Z28. I have the schematics, but they don't tell me where on the car they are. I found 2 wires on the rear drivers side above the tailpipe. They connect using a weatherpak. They seem to run to the tank. They go into the rear bumper. Could this be the sending unit wiring?

BigBadLou

iTrader: (3)

That sounds about right. I think the pre-85 models ran the wires under the rear bumper.
What colors are the two wires?

pimpimusmaximus

They look orange and black.

pimpimusmaximus

Is there a way to bench test the sending unit without dropping the tank? I have an extra fuel level gauge.

BigBadLou

iTrader: (3)

Bench test the unit in the tank without dropping the tank? The phrase "bench test" implies having the part on a work bench, not in a car.

Though you can measure its resistance while exercising the range of motion. For example, you can hook up an ohm-meter with the tank empty and watch the resistance change while you are filling up the tank (probably at home, using gas cans, I would recommend - I don't believe a gas station would let you do something like that :-) ).

However, I am not sure whether your sending unit is just like the 1986+ units which show 0 ohm resistance when empty and 90 ohms when full. I hope somebody can confirm that.

pimpimusmaximus

Yeah, I know. I was referring to not having to drop the tank. I can measure the resistance and then go fill the tank and re-measure the resistance. Does the car need to be running to test it?

BigBadLou

iTrader: (3)

Nope, the power can be off. Resistance measurement are normally powered from the multimeter.
You can also watch the progress of the resistance as you are filling it up (if you choose) to see whether the gauge gives smooth readings or whether it jumps around. (if that is what you need to determine)