Yesterday I drove my truck twice in the morning and the fuel guage was just above 1/2, on the third drive it pegged to full and stayed there. I drove the truck short distances twice more and it stayed pegged. This morning it still pegged when I started to drive it, I had a 15 mile trip and it stayed pegged for about 10 miles after that it very slowly started to fall and when I got to where I needed to go it was just under 1/2 (where I think that it should be). I sat there a minute and started the truck back up and it wa still just below 1/2. This is the first time this has happen in the eight years that I have owned the truck and I want to ask for any suggestion on where to start looking for a problem. Are the connection wires easy or hard to get to on top of the fuel tank to check for corrosion?

All sugggestion welcome.

I have also noticed in the last two weeks that as it has gotten colder my temp guage on the console will move up and done at an erratic rate going from 35 up to 46, down to 34 and back up again in a matter of a mile. I know the temps done't fluctsuate that much in a such a short distance. Are these two problems related or are there any suggests on my console temp gauge?

Thanks

 

I can't find anything in my notes, so if my recollection serves (ha ha) sitting on E hints toward not recieving input and sitting on F leans toward ground issue.

 

I had this happen also. I had just replaced my HPOP with an Adrenaline and was doing the first full throttle romp. The gauge went from 3/4 to full +. The sender float linkage (don't know the correct term) was bound up. My guess is the fuel sloshed with enough force to bind the linkage.

I dropped the tank, unbound the linkage and it has been working fine now for two years. I also did all of the in tank fuel mods while I had it dropped.

I checked the electrical diagrams in the tech section back then and didn't find any easy to check stuff that would create this problem.

 

All of the dash lights/gauages are working fine, just the fuel gauge was pegged to Full. Do I have to drop the tank to check the wires on the top for connection?

Thanks for the input.
Any more suggestions?

Thanks

 

I don't know on your truck if you can reach the wiring without dropping the tank. On my 550 it was either pull the bed or drop the tank.

 

I currently have the EXACT same symptoms, and have had for the last couple months. I checked the codes on the overherd console with my scanner and have a code P1203-- short circuit to power. I got a wiring diagram from my local dealer for the overhead console circuit and found that the fuel sending unit and ambient temp sensor both share the same ground. I have not had a chance to pinpoint or repair this problem yet myself, but I hope this infohelps you.
Aaron

 

Thanks Aaron.
I thought that it looked like a grounding problem.

would you (or anyone else) know where this grounding wire might be.

Thanks again, I will start investagating a little deeper.

 

Les, when I bought my truck 4 years I had the same issue, so I took it back to the dealer and they replaced the sending unit. Not sure how much troubleshooting they did, but that’s what was on the service note.
No help on the ground, prolly on the top of the tank access panel.

 

I was never successful at pinpointing the ground for that circuit...yet anyway. I will take a look at my schematic that I got from the dealer tomorrow and repost where to locate it.
Aaron

 

I had this problem with my 99 f350, what I found was the wire inside the tank had broke loose, I resoldered it on and no more problems for several years now. It was easy for me as I was in the process of changing from a flatbed to regular bed, would not want to drop a tank. Good luck to you.

 

Sorry for taking so long to reply. I looked at the sheet I got from the dealer and wouldn't you know it the way they printed it out it isnt readable! Ill try to get my Ford shop manual CD up and running and repost.

Aaron

 

Thanks Aaron

 

well, I finally got my computer genius brother to get my Ford program up and running. This thing wasn't as thorough as I thought and couldn't give me a pinpoint location of the connections. I wish I had better news for you, and I wish you luck in locating the problem.

Aaron

 

In a weird way I think that my fuel gauge pegging out to 'full' is 'fixed'. I found out that in the last couple of weeks my GPR was shorting out.... I have a 'plug in volt meter' and I check my Batts and GPR and Alt. several weeks ago and everything was 'ok'. About a week after that I noticed my 'temp' (out side) read out on the upper console was fluxuationg wildly and a couple days after that the fuel gauge pegged out full..... The temps got down to very cool outside and my truck was a little hard to start. I tested the Batts and GPR again and found the GPR was bad. I changed the GPR out for a new one and have had no problems starting or with my outside temp gauge or the fuel gauge since then. I think/hope that the shorting out of the GPR had messed up the electrical input/output of the Fuel and console temp guages.

 

I have never heard of such of a condition, but that never means it isn't possible. I hope you got her taken care of for good!

Aaron