new gas gauge still pegged full
 

my trucks gas gauge was pegged on full, I unhook the wire from the sending unit, still reads way past full. SO I thought the fuel gauge was bad. install new one same things happens.....

what is it sending unit wire shorted out???

Re: new gas gauge still pegged full
 

Sounds too me like it's grounded
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Re: new gas gauge still pegged full
 

Trace the wire from the dash to the tank, I bet it's shorted against the body somewhere, grounding it making it read full. Look under your sill plates, one of the screws holding it down may have pierced the wire.
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Re: new gas gauge still pegged full
 

Empty is 0 ohms=grounded;
Half is 44 ohms to ground;
Full is 88 ohms to ground
your sender wire is open between the gauge and sender

Re: new gas gauge still pegged full
 

You are grounded out somewhere for sure. Tracing the water is your best option, or just replace it. Grounding it out, it will read full. With unhooked it should read about a 1/3 of a tank ( I think). Simple fix.

Re: new gas gauge still pegged full
 

68K30 has the information listed correctly. Try grounding the terminal on the fuse panel where the brown wire from the tank plugs in. It should go to empty with the key on.

Also, make sure the fuse that feeds the gas guage is good.

Jim

Re: new gas gauge still pegged full
 

Good fuel guage reads about 90 ohms+- 5ohms or so unwired. Just checked. Wire from fuel sender unhooked from sender to ground should read approximatley the same, just checked also. I am checking all of this for a guy at worrk is having some problems with his. Radings may vary on temperature a bit. Hope this helps.
Ron

Re: new gas gauge still pegged full
 

Thank you for the replays...it was a big air gap.....