07 6.0l, started up great this morning, was 15f out. Was driving home from snowmobile trip, hauling four sleds, and an enclosed trailer. Roughly 4,000lbs total. Hop on the thruway and notice the truck cannot get past 55mph. No brakes frozen on truck or trailer. Later, driving up a reasonable grade, truck loses power, begins to shudder. I ended up crawling up the hill in second gear @ 15 mph and pulled over at top of hill. Truck idled rough for a minute, then smoothed out. It revs fine with no hesitance. Hesitance only comes when truck is under a load. Now for my obd results. EOT is 190, ECT 186. no codes thrown, hpop pressure ranging from 550@ idle to 2700 under load. Fuel flow rate is around .27 per minute under load. Fuel filters have 6100 miles on them, oil was changed 1000 miles ago. Shell rotella 5w40, and diesel additive used. Any ideas?

 

Water in fuel? Drain FICM and change those fuel filters, you could have got a bad batch of fuel, or a bit of water. Do you get a WIF light? I also wonder about FICM voltages, batteries and alternator.

 

Ficm is 48.5 while running, 47.5 when starting. No wif light. Gonna drain pump and clean egr tonight. Voltage is 14.5 while running

 

What is your fuel pressure? Below 45 will kill your injectors. I would not want anything below 50.

 

unfortunately i Don't have access to a pressure tester. All i am able to read is fuel flow as reported by the ecm. it says .27 gpm under load. also hpop pressure is around 2500 under load.

 

Another thing i noticed, we stopped to eat lunch, so the truck was shut off for aproximatly an hour. When we hit the road again, it ran fine with no issues for aproximatly half an hour. half an hour in, it began to lose power again. again, it runs normal at speeds up to 45 mph. past 45, it crawls to 55, and loses speed under load. when its off the trailer, its acceleration past 2500 rmp is noticeably slower, but normal top speeds are attainable.

 

Are you able to check for codes at all? Did you just fuel up before getting on the expressway?


I hope you've made it home. I go snowmobiling almost every weekend and this is my biggest fear.

 

Fueled up friday, Ive burned almost half a tank of the fuel i got. it came from a high volume dealer, so i doubt the fuel is bad. no codes are being tripped. i have the torque app and a bluetooth obd2 adapter.

 

Also, no smoke at all when it loses power.

 

Any smoke when the issue happens? Ford/Racor filters correct? Normal boost?

 

motorcraft filters all the way around. when the truck doesnt lose power, boost is normal. it seems to lose boost as the engine loses rpm. in other words, i dont think the engine is losing power due to a lack of boost. i think the boost is decreasing when the engine loses power. my gut says this is a fuel issue, i'm just not sure what it could be. wif light hasn't tripped, truck only has 31000 miles on it, and the fuel flow levels as reported by the obd seem normal. im relatively new to diesel repair, and am doing my best with what ive read on here. the fact that it happens when the truck is warm points to a hpop issue, but the hpop pressure reading is normal. honestly im stumped :-(

 

You have to INCLUDE IPR% to Condeim a HPO Problem

 

Does your ICP pressure ever hit 4000 PSI at WOT? It should or very close to it. What is your IPR% at KOEO, at idle and at 2500 RPMs?

 

Fair enough. I'll have a look soon. What is a normal ipr reading?

 

Take these numbers on a cold start and a hot start.