Hi there, I'm new to the site and have a problem with my 1999 SD350 v10 . Whenever the key is on, my fuel gauge reads completely full, when the key is off, it returns to completely emply. Any mechanics out there that can lead me to the problem. Thanks

 

If the guage PINS itself to the high side when you turn the key on,The gauge/sending unit circuit is grounding out completely.

 

mine just did the same darn thing so I thought Id hop on here to see if anyone else was having troubles..

EDIT:

Mil1ion?? any ideas on where to start looking to see why/where you are getting grounded??-- thank god for the idiot light that is going to tell me LOW FUEL . HA

 

This should explain as it also appplies to the fuel gauge and sender.

I always start looking at where the wire attaches to the Sending unit & work my way back to the gauge.


https://www.ford-trucks.com/forums/s...d.php?t=244131

 

thanks for the help, I will start looking for the ground. Also thanks for the info about the idiot light still working, that will help keep me out of trouble while I'm looking for the problem

 

Mil1ion, Is the sending unit in the tank?

 

Yes, the sending unit is in the tank. Sometimes you have to buy the fuel pump assembly to get a new sending unit.

And also remember on some of the newer trucks, ground will give an empty reading instead of full.

I thought I used to have it straight. With GM cars, ground was empty, Ford was the opposite, ground was full. Then it was pointed out sometime in the late 80's I think, Ford switched it around so it was like the GM system. it's very confusing.

It doesn't really matter though. Take the sending unit wire off the tank connection, and the guage will swing all the way one direction, then ground the connection at the tank, and the guage will swing full scale the other way. This is a good way to test the wiring and the guage. If it passes this test, then it's usually a bad sending unit.

 

Thanks Dave, I'm sure that will help a lot. Wayne