Just picked up a 94 F350 5.8L and the gas gauge worked all day yesterday and all of sudden this morning its not working. I searched and read the hundreds of posts about these problems, and my gauge is acting a little different. When the truck is off key out the tank reads at a 1/4 but when the ignition is on it reads empty. I did just replace the P.S pump and did a lot of exhaust work so maybe I broke a wire somewhere?? I find it hard to believe that both the front and rear tank sender just broke overnight but maybe they did idk?

Now I have the dual tanks but how do they exactly work? Can you switch tanks while your driving or is it something you need to pull over to do? I'm trying to figure out if the switch even works. The PO SAID the rear tank works but who knows.

 

sounds like a ground wire
yes, you can switch tanks while moving at any speed

 

Ok thanks for the response. Where are the ground wires that are directly responsible for the fuel gauge and sending units?

 

BUMP.. Anyone?

 

Well it would not be a ground as the gauge would peg pass full if you lost a ground or had an open wire/plug.

What you have is a short to ground, sunk floats or a bad gauge.
If none of the gauges are working you could have lost a ground at the cluster.

 

I also thank you subford. Some times my fuel gauge will jump past full for awhile, then go back to empty with an occasional needle bounce. Must be a loose ground making and breaking contact.
Thanks, Jerry

 

Maybe but more than likely you have a bad contact between the wiper and the resistive element on the sender.
You can pull it out and clean it but most just replace the sender.



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