Hey guys, well I love my new truck.. However the gas gauge isnt working....well its kinda working. I wanted to see if you guys could help me trouble shoot. When I turn on the truck it the gauge needle moves to a little above E. I filled her up this morning so I know it has plenty of gas. If the gauge is getting signal but not showing the actual amount of gas what could it be? The sending unit?

 

Yes, most likely the sending unit.

I believe you can short the sending unit wire to ground. If your gauge goes all the way to full, you know the gauge is not the problem. I have not tried that test on my truck, but it has worked on other vehicles. Someone will chime in if that is incorrect.

 

That's the correct procedure. In almost all cases, the problem is either a sunk float, or a bad ground at the sending unit. The test above will help isolate which one is the problem.

 

Where is the sending unit located? My tank reads above full until 1/3 tank where it reads full, and from there it shoots down rapidly. I had a shop look at it out of boredom and they said the float was good but really sensitive - something along those lines - so I suppose I may as well check out the sending unit ground.

 

The sending unit is in the tank itself. This shop doesn't know what they're talking about; I sure hope that "diagnosis" didn't cost much. Sounds like a bad rheostat in the sending unit. You can easily check with a multimeter. If your gauge ever reads FULL, the ground is fine.

Another side note: there is no way to verify the float integrity or sending unit resistance against float arm travel without physically removing the sending unit, so unless that shop removed the tank, they are straight up lying to you about what work was performed.

 

I had the truck in for them to get all my wiring working properly as I needed it inspected for importing. I think they only gave a five minute look at the tank, but I really don't know. A functioning fuel gauge isn't necessary for inspection and I brought it in there for them to make it passable and nothing else. They told my dad what they did as he was the one who picked up the truck, and he told me after, but both through the middleman and time I've forgotten what exactly was done.

I'll replace the sending unit one day, but until that day I'll keep on fueling up every 100 miles.

 

Fuel sending unit float is made from two pieces of copper soldered together. Solder breaks down, gas seeps in, float settles to the bottom of the tank.

COAZ-9202-B .. Float same: 1957/79 Passenger Cars/Trucks, 1961/79 Econolines & 1966/79 Bronco's / Available from Ford, but...

Carpenter sells a one piece brass float that'll never leak for about 5 bucks.