I filled up my tank and several days later the fuel gauge went to empty and the fuel light is on. When I turn the key on, the gauge goes below empty and turn key off, it goes back to empty mark. I have held down the odometer reset/select button for 10 seconds and then turn on key so it goes into engineering mode and do a gauge sweep, and the fuel gauge does a full sweep. I have ran 2 bottles of Techron thru it. I disconnected the main connector that goes to the back, under the master cly, and it read 99 ohms yest. and drove it today and it now reads 96 ohm. I called the local dealership yest. and the guy told me they could re-flash the cluster for $50 to try to fix it. I called back today to get an app. and a new guy said doesn't think re-flashing do anything.
Does anyone have any suggestions on what to do? Has anyone ever had theirs re-flashed? I'm at a lose on what do next.
It has no trouble codes.
The wires I am probing in the harness are yellow/violet and green/blue

 

If I had to take a guess I would say you have a bad ground for the fuel sending unit or the sending unit went bad. I don't think re-flashing the ECM is going to fix that.....

 

I just took the cluster out and there is 96 ohms at the cluster. I'm thinking the gauge is bad? It is just confusing when it will move when the key is on and sweep when tested.

 

If it sweeps when tested the gauge is good I would think....problem is at other end I would assume

 

I had same problem with my 02 f250 5.4. I bought the truck used and had the exact problem the problem was the sending unit. lucky for me this happened under my 60 day warrenty from used car dealer. it has been 4 months and gauge has been spot on ever since

 

After thinking about it, I wanted to see it in action so I jacked it up and then had someone let it down so I could watch the MM. It jumped all over the place from 0 to 1000 and after a few minutes it settled back to 96. So I guessing being perfectly still it works, but movement makes it spazz?
I'll try the sending unit. Thanks for the advise.

 

Pulled the sending unit and it works fine. Had a friend look at it with his Matco scan tool and he said the fuel reads almost half of tank.
I sent the cluster here Brian's Speedometer Repairs - Home - Muldrow, OK. Will see what he says.

 

I got my cluster back and the fuel gauge works. He said the #23 green/blue trace wire was fried (#24 yellow/violet is the other wire from the sender). It is still a mystery why/what fried it...was it a fluke or is there something in the harness or cluster that caused it? Fingers crossed that it was a stray gremlin.