Pontiac Grandam 93 - gaz gauge problem

Still have the old unit? Unplug the wire harness going to the gas tank and plug the old unit in. Move the float up and down on the old unit and have someone watch the gas gage. If the gage works then you know the problem is with the new unit you put in. This is why you should check the replacement unit with an ohm meter before you go putting it in.

A used fuel pump is about the worst idea I've heard in quite awhile. A gage that reads full can be do to a shorted wire, also. GW

"B> > > Hi,

-- GW - Conservational Ergonomist - note incorrect email address "It's good to yell at people and tell them you're from Tennessee. That way you'll be safe." - Gary Busey

Yes. Thanks, I couldn't remember if wire shorted was full or empty.

According to my '92 GA shop manual the fuel gauge sender is at 90 ohms when full and 0 ohms empty. An open wire, not a short, would make the gauge show full all the time.

However, my own experience is that the "wiper" arm does not make good contact with the resistance strip on the sending unit. It's my theory that the used sending unit's sliding contact area could have oxidized if it was not submerged in gasoline in the scrap yard (or wherever it was).

The sending mechanism is rather delicate. It does not lend itself well to cleaning/polishing the contact surfaces. I would very much welcome an aftermarket replacement unit.

Thanks to every one that provided me solutions and comments.

The problem is now solved. The two root causes were a wire cut under the back seat and a bad resistance strip of the sending unit.

I know that playing with used stuff can bring that type of problems but I can't afford the $500 (Canadian) asked by the GM dealer for the pump assembly.

Thanks again.

Daniel

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