Hey all,

did a search but have not seen a related thread. Having an issue with my Ex 6.0 where it is loosing power on long runs or high speed. Actually started only when I would be on the highway running 70mph or more. truck would start to stall out and loose all power. still running. but no power to even maintain speed. pull over and sit in park for a few minutes, then the truck would pull away and drive normal again. It was doing this for several weeks.
Now yesterday, the truck was running for a long time as I had the kids in the truck while we waited for another one. So the truck was idling/running for a good 30 minutes or so. then when I went to drive the same thing happened but this time it was at 45 mph. again, stop and shut the truck off this time for 3-5 minutes, then restart and truck drives fine. Had a heck of a time getting home yesterday as i was about 20 minutes from home and needed to pull over and shut off the truck at least 8 times on the way.
it now seems like it might be something related to the truck being warmed up as it did idle for a long time yesterday before this started. crazy and puzzling.

any hunches at all?

 

you need to verify that you have 60 psi fuel pressure at idle and more importantly maintain 60 PSI at WOT. I had same issue verified with manual pressure gauge taped to windshield. ended up rebuilding my fuel pressure regulator. i can post its if needed.

 

Also, What's the IPR % & ICP (volts & pressure) cold, when it acts up driving, & after it acts up at hot idle.

Cold Idle
ICP psi.=
ICP volts=
IPR %=
Fuel pressure=


Hot Idle
ICP psi.=
ICP volts=
IPR %=
Fuel pressure=

Driving @ 2000 rpm & it's Acting up
ICP psi.=
ICP volts=
IPR %=
Fuel pressure=

 

Yeah, I'd go with fuel pressure too. I see you're kinda new and am not sure what data reader you have, if any. Fuel pressue isn't available to those readers; it's not a digital sensor. You have to connect an analog gauge and monitor it while driving (the taping to the windshield). I'd also start the diagnostic process as 87Dualy suggests, actually first, just to eliminate obvious issues.

ut, I have a data reader. If you don't, and you need this truck to work tomorrow (takes a few days to get a OBDII connector), this is an example where I'd consider throwing a part at it. I'd consider the truck's mileage and previous service history as well, but fuel pumps are a service part; you'd be replacing it at some point anyway. If that doesn't fix it, you have a known-good spare. Or, buy a junkyard pump cheap, just to see if that fixes it. If it came off a salvage truck that was scrapped because it was in a wreck, there's a 99% chance the pump was working at the time, and it's location on the frame rail protects it in almost any wreck. Go to a Pick-u-Part place. You need some cheapo plastic fuel line disconnect tools.

Of course, check your filters first - bad fuel may have just clogged you up.