My gauge keeps dropping back to empty then back up, replaced leveling unit in the tank and it said full all the time. put the old leveling unit back in and it reads the fuel level right when it works, but it still drops to empty and that darn bell goes off could it be the in dash gauge ? had the tank down 3 times trying to fix this all wiring is good. The new leveling unit was a direct mopar replacement, could it be bad? thanks

 

Well its going to, when you run the tank out then full it back up. Seriously though. I would double check my grounds. connections again. If you have an digital ohm meter you can check to see if the level unit you have is bad. touch the 2 leads coming out for the level unit. Move it up and down see if you get a steady change in the reading. It's easier for me to do things then try to type it out and explain it. Sorry but hope it helps.

 

did you mean the main grounds body to frame of the truck? Which grounds are you talking about, really confused about what could be wrong. Thaks any help would be great

 

I was talking about the ground for the sending unit. in and around the fuel tank. It definitely wouldn't hurt to clean the grounds all around. With what you described, it doesn't sound like a guage problem. the symptoms lead me to believe it is a level unit problem.
Now when you replaced the new level unit, it sounds like to me the arm that moves up and down the sending unit was stuck at the full position. When I've replaced these before I've had to make sure everything was moving before buttoning it all back up.

 

with the unit out of the tank and hooked up I could move the leveling unit up and down hold it half way or down and gauge would not come off of the full mark on the gauge with the old leveling unit it would show the level moving slowly as you move the leveling arm however when I reinstalled the unit it was back to the same old thing. I was very careful when I put everything back together to install it right maybe some explosives will do the trick any ideas to check will be greatly appericated thank you

 

A 22 year cummins fantasy became reality on 5/4/12, when I took possession of a 98.5 3500 4x4 quad cab 24v.

It has the same problem with fuel gauge. I will start checking / cleaning ground connections this weekend, at least the ones I don't have to pull tank for, since it is still nearly full.

 

Well that definatly is odd. works out the tank but not in. with guage working with one, tells me again not a guage problem. I'm wondering if there is a break in the line allowing fuel to enter and cause it to lose its conductivity. If i could I would return the fuel pump you bought and try a 3rd. aslong as all the connections are good. You possibly could have gotten a bad unit out of the box which is an unfortunate reality nowadays.