I have an 88 that is giving me fuel gauge problems. The gauge stays pegged out on Full, even when the battery is disconnected, and switching front/rear tanks changes nothing, removing the front/rear switch changes nothing. I removed the cover from the cluster and moved the needle to Empty, hooked up the battery, and when I turn on the key it goes to full and stays.
Bad ground? If so, where?

Thanks.

 

There is another member with the same issues.
We could really use a little advice.... anyone?

 

do u have duel tanks.because i was told that the transfer pump sticks in one spot and grounds out. dont know if its true

 

i have an 88 and had the same problems. changed out the sending units and works like a champ. had to change the front one out twice

 

The float on your sending unit is bad. It's a brass float that gets a little pin hole in it. This is boringly common on these trucks. Last time I bought one at my dealer, he had a box of them under the counter. Changing the entire sending unit will get you a new float, too, but it's a lot more expensive that way.

 

but if that is the problem then why dosent it swich tanks from front to rear

 

it is probably a bad ground somewhere i would check your wiring

 

A gauge that pins on full and stays there usually indicates a bad ground. Because it's happening on both tanks, I'd check and see if they share a common ground.

 

was wondering if any body are some body has are can post a picture of the fuel tank wiring diagram from the duel tank to the dash on 1989 f250 thanks for all your help

 

hey jake was wondering if u have problems with the other gauges like oil are water.if so your ivr has probley went bad.

 

Wouldn't that make it stay on/close to Empty instead of full?


I do have dual tanks. All other gauges work great.

As of now I'm gonna check for bad ground(s). Plan B: pull sendin units and inspect floats.

What are the symptoms of a bad tank selector switch?

There is no gas in rear tank... it has a hole right now. I believe this would keep me from being able to select it?

 

A gauge pegged on full is and open circuit not a short.
Could be the selector switch on the dash.
Bad Gauge on the cluster.
Sending unit in the tank with no Electrical Continuity through it.
If the fuel pump(s) run the ground is OK.



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