Pontiac Grandam 93 - gaz gauge problem

Hi,

Recentely changed the fuel pump unit on a Grandam 1993.(complete unit including gauge gotten in a scrap yard)

Since that time, the fuel gauge indicates full as soon the switch is on when the tank is not.

Is it a sure indication that the tank fuel gauge is defective or could it be a wiring connection problem.

I just bought this car and I don't know if the previous gauge was working properly.

Any opinion or idea about the testing I can do.

Thanks for your help.

Daniel

Reply to
champagne daniel
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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.

Reply to
Bon·ne·ville

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

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Reply to
Geoff Welsh

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

Reply to
=?x-user-defined?Q?=AB?= Paul =?x-user-defined?Q?=BB?=

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.

Reply to
Silver Surfer

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

"Silver Surfer" a écrit dans le message de news: tyGMb.37196$I06.238665@attbi_s01...

Reply to
champagne daniel

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