Hey all, I’ve got an E99 F-250 7.3 auto w/ 337k. Recently I’ve run into troubles with the engine lacking serious power in higher RPM’s, usually above 2200. Below 2200, almost where you’d consider it “lugging” the engine, it runs great, and has tons of power. Above that threshold (which isn’t set in stone. Sometimes it’s higher, sometimes it’s lower), the truck seems to sputter & act like it’s running out of fuel. It won’t die, never has any actual failure, it just seems to run out of power. It’ll hit an arbitrary speed it will do, and then to go any faster you need to upshift to get the RPM’s lower to go anywhere.

the truck has a Hydra chip, but I’ve set it to pass through (00), so I don’t believe that’s causing this. I don’t get any codes nor SES light.

Occasionally, the when the truck starts, it acts like it just got fuel pressure back. Rough idle, cackles, but it smoothes out within a few seconds. Once it gets that pressure back, it seems fine.

Here’s a list of things that I’ve done to the truck recently:
•Fuel Pump (Bosch)
•Harpoon & Hutch Mod
•Injector Shims
•UVCH Harness (Motorcraft)
•Glow Plugs + Relay (Motorcraft / White-Rogers)
•Passenger Side Fuel Line (Motorcraft)
•CPS (Motorcraft)
•ICP (Motorcraft)
•EBPS Tube

There is fluid in the valley, but it’s further into the valley, away from the fuel bowl. There’s no obvious markings from fuel lines as far as I can tell.

Any thoughts? It’s been driving me crazy, because this truck is my daily driver. It seems it will reliably start and drive, but I’d rather not hurt the engine.

TIA

 

Have you checked you post filter fuel pressure?

Have you monitored icp and ipr values?

Is your air filter clogged up?

Why did you shim injectors? Did this issue start after that?

 

My mind immediately went to fuel pressure. Looks like you’ve replaced the pump and tank items. Did the issues start before or after the Hutch mod?

I’d start with a fuel pressure test as Eric mentioned. There’s an “easy method” in the Tech Folder thread. It’s pre-filter but at least you could do it fairly easily and read while driving. https://www.ford-trucks.com/forums/a...4&d=1592859516

There’s another aspect to the fuel system that wasn’t mentioned. The Fuel Pressure Regulator which is on the fuel bowl. If replacing, I recommend the full rebuild kit which includes the plunger, not just a spring kit. I’ve been down that road.

 

Since the other guy's went fuel I'll throw boost out there, just cause I gotta be different. What's the status of your up pipes, see an soot or other sighs of exhaust leaks? Done any reading on boost leak testers? They can be assembled from hardware store bits and pieces pretty easy. You'll need a source of compressed air, a bottle of soapy water, and somewhere quietish to do the test. I believe @RacinJasonWV has a video floating around that shows what a good test looks like.

 

Thanks for the reply. ICP & IPR read normal as far as I can tell. ICP tends to cap at ~2600 under hard accel. IPR & never reached abnormally high as far as I could tell, but I’ll have to grab the scanner & take a drive again to check exact values. Air filter is perfectly clean.

I shimmed the injectors due to a cold start issue, and general preventative maintenance. The shims didn’t solve the cold start, I had bad UVCH wiring to the gp’s, but I left the shims in there because the tolerances in the injectors pre-shims were very poor. This issue started after shimming, yes, though the truck sat for about 5 months as well.

 

Thanks for your response

At idle, I checked the fuel pressure at 60psi. I believe the actual pressure is higher, because I had a serious leak on the gauge that was spewing fuel. I did not check pressure while driving for that reason.

I’ll also note that the max turbo pressure I saw was 8lbs, but I’m skeptical of a turbo issue. The shaft has zero play, and it feels like a fuel issue.(jerking, rough running, etc)

 

I had also considered boost/uppipe leaks but sort of dismissed it since it was described as only happening at higher rpm. Definitely worth a look though.

Here’s a link to the reference video. I so wish I’d have thought to take a “bad” one before repairing.

7.3 Powerstroke Good Boost Leak Test Reference


I think it’s worth finding a way to confirm fuel pressure during the poor running condition. Might need to rent/buy a new gauge if yours is bad. The easy method has you run it on the side mirror I think.

Another consideration is air in the fuel. Even with the Hutch mod you could have a leaking compression fitting or such. Udsuth has a good explanation of how to look for air. Basically it’s opening the fuel bowl drain and checking it out while pump is running but I can’t remember the details.