Recently my 2001 7.3s fuel gauge shoots up past full when the key is turned on. Over the summer (about 4 months ago) I took the bed off and put all new bed supports on and under coated the whole frame. I had removed the fuel tank and took the sending unit out and upon taking it out a breather valve line that connects on the top of the tank and connects on both sides had corroded so bad it fell apart and I never put it back on/replaced it. so my tank has a decent coating of fuel on the top and outside of it now. Could that cause it to give a bad reading if it gets into the plug end?? Is the sending unit itself going bad?? I have no clue what would cause my fuel gauge to be acting up all of a sudden. please help

 

If everything is plugged in and making a good connection, it could be a bad sending unit.

The pump is separate (it's mounted on the frame), but that in-tank module is still pricey.

I'm sorry I don't know a good way to test it without removing it from the tank...

 

it won't be difficult for me to take it out to test it because the bed bolts and tank straps are all new. So I could get to it. It's not like a fuel pump that buzzes when healthy, so I have no clue how to even test it. I'd rather test it than spend hundreds on a new one. (Airtex are cheap, are they decent pumps if I do have to replace)

 

I have a bad sending unit that is behaving the same as you describe.

If you have a laptop or phone, OBDII connector and can download Forscan you can see if it is in fact the sending unit. You'll get a B1201 or B1203 or both if it is bad.

Check the link at the bottom of my signature "B.E.S.T." to see if there is someone near you with AE of another tool that will read codes.

Link to a recent thread that may be helpful:
https://www.ford-trucks.com/forums/1...e-cheap-3.html