i just bought a 94 12 valve and the fuel gauge stays on E every ounce an awhile its goes up then drops down. The fuel light comes on an off ocasionally. Any ideas if the sending unit is the problem truck has 259xxx miles on it.

 

Sounds like sending unit to me. Had the same issue a while back and it's starting again where it reads normal 99% of the time, then it will suddenly drop to E. Some say it's easier to drop the tank, but I found tilting the bed works fine as well. What I wished I had done the first time was change everything there instead of just the sending unit. Now it leaks a bit if I try to fill it all the way up.

 

try leaving the key on and the truck running while you fill up. i have had the same problem with mine with 245k and everytime it starts i fill up with the truck running and it seems to go back to normal until the next winter. just my $0.02

 

mines haywire 24/7 it drives me crazy

 

Make sure the wires on the connector on top of the tank are in good shape or at least not cut anywhere. Make sure the connector is good and spray some contact cleaner or something in it. If the tank has been messed with before, they may have not put the unit back in right. If it is turned or something the float will just hit the walls in the tank and obviously not work right. You can take the sender out and move the float up and down and see if the resistance changes as you go up and down, if it doesn't then the sender isn't working.

Taking the bed off is the best way because you can clean all the stuff out of their while you have it off that has built up over the years. My whole tank had 1/4" of sand/mud/crap all over it, the frame, everything. I got out the power washer and now the truck probably weighs 50 lbs less

 

i need to check all the wires on mine then because ill fill up then 30 minutes later itll show a quarter tank and go to e and not come back up. i also have a 35 gallon tank and the funny thing is when my gauge does work properly and gets to e ill fill up and only get like 27 gallons worth

 

They aren't very accurate. Mine works fine but stays above F for 200 miles then will go fast to half a tank and stay there for 200 miles then drop slowly to 1/4 then will fly down to E but will stay on E for a long time. I have bottomed out E though at 34.6 gallon topoff, was on vacation and the toll road didn't have any stations so I just kept going, almost 800 miles on that tank.

The wires are easy to get to, just reach up and take the connector off and look. If you suspect the float is hitting the wall just loosed the huge plastic nut and rotate the sender a little.

 

800 miles ha ha i get half that but like i said my gauge goes to e and i think im empty

 

You can test the wiring by just taking off the connector and sticking a jumper between 2 contacts which 2 I am not sure, the 2 I have them in make it go to F. Unplugged it should be on E, jumpered it should go to F. If that is fine then you will have to take the bed off or drop the tank to do any further testing since it will probably be in the sending unit that is in the tank.