I have a 2007 F350 DRW 6.0L Lariat w/CC, she is totally in factory form with around 130K on odo. What I originally noticed was sometimes when I'd refuel tank from like 1/2 tank the fuel gauge needle on my cluster would linger around 3/4's and slowly take it's place at "F". Then 2 months later the fuel gauge goes totally off, needle at "E" and CEL comes on a few minutes later. I get DTC p0460(circuit A malfunction) and I start doing some research. Anyway I go to gas station to add some diesel fuel, Diesel Kleen and Ford Octane Booster. It's now full and the fuel gauge magically starts to function again. So after a month of doing this this is what happens; every time I reach slightly under 3/4's of as tank the needle is unresponsive. This just happened again this morning and like clock work refilling brought gauge back to life. I'm thinking fuel level sending unit because it has gone dead numerous times in same exact spot. It would be nice if it could be resolved with an updated software program at a Ford dealership. It's like it's hitting a dead spot when the float get to the 3/4 level and if I add diesel fuel to raise level of float it re-closes the circuit. What do you guys think? Any suggestions? Hopefully I didn't forget anything.

 

I'll bet you answered your own question. Likely a spot somewhere that went funky and not sending the proper voltage where it belongs.
At least owning a 6.0, you know well enough to keep it from running dry

 

It sounds like you're on the right track. I'm guessing that truck sat at some point with 3/4 tank and the sender in the tank has a dirty corroded spot on the rheostat. You may be able to disassemble it and clean it with electronic cleaner and pencil eraser or buy a new one and replace it.
While the tank is down you can cut the vent tube off inside so you get a faster and more complete fill-up at the pump.

 

Definitely the sender. Seen this lots of times. It's always the sender.

 

Been there done that.
Pull the sender out of the tank and you might be able to save it.
Remove the little plastic cover and with a q-tip and rubbing alcohol
gently clean the resistor pads and the sliding contact. Be very careful
it can break.

Here is the tank lock ring tool and the tool on the ring.





You can see the contact and the resistor pads. Only use light pressure.



The same type of sender is in your truck as this one that happened
to come out of an older Ranger. The stupid thing is the one in the
diesel truck is about $300 for a new one. Also two things to do while
your in there. Replace the big tank to sensor O-ring and do the
Harpoon Mod sense you are into the tank.





Sean


6.0L Tech Folder

 

I had the same P0460 code and issue on my truck at 1/4 tank. I used Clear Diesel for several consecutive refills and use quarterly now. I rarely have the CEL/P0460 now.

Clear-Diesel Fuel & Tank Cleaner | Power Service

 

If I go to the trouble of dropping the tank, a new one is going in. I hate doing the same job twice.

 

I normally use diesel kleen and I tried using the Ford dealer cetane boost when it went off...poured that stuff in then filled with diesel.

 

Power Service makes both Diesel Kleen and Clear Diesel. Clear Diesel primarily for fuel tank; Diesel Kleen for cetane boost and injector cleaning.

If water in fuel tank is causing corrosion on fuel sender, then Clear Diesel may help. It certainly seems to have helped mine as I rarely get the P0460 now.

If this hadn't worked for me, I would have replaced the sender.

 

Clear diesel is for the tank, gotcha...i'll get a bottle and wait until im at a 3/4's again. appreciate suggestion.

 

The only reason I was even in at the time was the top seal was weeping and
I was not ready to spent the $300 or so on the sender. It's been fixed sense
spring 2013. So I guess I did not need to spend the $300. Also the tank did
not come up the bed did ot I should say 1/2 the bed did. U only removed the
bolts on the one side and loosened the other side and tipped the bed up and
blocked it in place. The bolts had been out for other reasons and were easy to
remove. So I took a look when doing the seal. Was also a good time to do the
Harpoon mod. Turned out that it had been done and that is why I had the leak.
The nut was not torqued down to the correct value when the mod was done.



Sean


6.0L Tech Folder

 

Anyone ever find the rheostat for sale separately from the sending unit?

 

I once found someone that was saying that there is a kit.
But I don't recall who or where.



Sean


6.0L Tech Folder

 

So I used the DK Clear Diesel a few times with some Ford Cetane Boost and it seems to be helping. My tank guage is reading like 1/4 tank right now and it hasn't done that in months.

 

Thanks for the update. Your results says something about the products. If you think your tank was scungy you may want to change the fuel filters sooner. Sounds like the additives are cleaning it up and that stuff has to go somewhere.