When I switch to my front tank the fuel gauge needle swings wildly from full to empty. The truck runs normally. On the rear tank the gauge displays the correct level of fuel so one must assume the problem is the sending unit in the front tank.
Does anyone have any suggestions of where I should begin to look for the problem.

Thanks,

pbgsho2

 

I believe that most of the factory front tanks have a brass float. They develop holes or cracks that can allow fuel to enter thus compromising its ability to float. Full of fuel it is now pretty much buoyant or even weighted and will most likely go wherever the motion of the fuel takes it(up or down). Seems like yours may have chosen down...

 

I would take a look at the ground wire from the sensor

 

My truck was doing that on one tank a couple years ago too. I was going to look at the ground when I got a chance and could find it, didn't know where it was, then it quit doing it, fixed itself I guess.

 

Mine does the same thing....

 

And I'd listen to Rick...

 

This is an update to my fuel sending problem. Several days ago while driving to Walmart, I switched to the tank with the fuel sending problem. It began to buck and run really rough. Switching back to the rear tank it smoothed out and ran normally. While getting fuel I decided to put some in the front tank knowing that this would complicate dropping the tank to replace the sending unit. After leaving the station I switched to the front tank and was surprised to find the engine running normally and that the gauge was stable and appeared to read the correct amount of fuel.
The only possible explanation is that the tank was really out of fuel with the float at it's lowest position that caused the strange reading. When I originally posted I incorrectly stated the gauge was pegged on empty when it was actually reading full. Go figure.
To the respondents who stated the gauge fixed itself, was your tank really empty and with the addition of fuel did it began working? I don't like things to fix themselves but in this case I will accept it.
I did check the ground wire and found it attached and properly grounded.

pbgsho2

 

Could had some crude stuck on the sending unit.

 

Mine wasn't empty, when I'd fill it it would go all the way up, bounce back down to half or so, and just kinda do that some. Like I said, I did nothing to fix it, been about a year or so now with no more issues???

 

My front tank started doing this about 2 weeks ago. Haven't had a chance to look at it, but I'm going with the ground wire as it jumped up a few times and settled slowly back to MT. That's with a full or MT tank.