Itook my 95 f-150 302 to get a new fuel pump and new end plug. So i pick it up when its done and it drives fine except the fuel guage starts jumping past full and back down. i take it back to the shop and they check it out and told me they hooked up the end plug wrong and hook it up right and works fine for a few days and then does the same thing could it be the fuel level sending unit got fried when they hooked it up wrong.when i first start the truck it shows the right level but when i drive it and give it alot of gas it just pegs past fuel. any hepl would be appreciated thanks.

 

Sorry i really dont have an answer for ya, But i am having some of the same issues..

What were u charged for parts and labor?

 

Number one you can not hook it up wrong inside the tank, it only has one wire.
The plug on the pig tail from the the top of the unit (FDM) will only plug one way.

Do you have two tanks?

If it jumps pass full you have an open in the wiring between the sender and the gauge.
If it jumps back and forth you more than likely have a bad sender in the tank.

 

it was not the plug on the fuel pump itself it was the main wring plug that the pump goes into, they said it was better to upgrade it so everything was new idont know which wire was hooked up wrong the pump was working so i assume it was sender wire and ground wire that got hooked up wrong

 

If those wires were swapped the gauge would be pegged below empty all the time. Somebody is fibbing to you.