Hello everyone I got a question I have been battling up hill acceleration for a long time now trucks got good fuel pressure as it was tested more then twice tank was cleaned out and reinstalled injectors are decent and in a scanner everything seems normal from a few trusted diesel techs anyone got any ideas what’s going on. Truck is a 2003 Ford F-350 with an 01 7.3 powerstroke

 

Measure fuel pressure while the engine is under load, climbing the hill. It will show good pressure all day long at idle, but that's basically useless information in diagnosing a power loss as you are describing. Mine was fine, but dropped to 20 psi at the first hill I came to. The factory fuel pump has a screen inside the inlet side of the pump that greatly hinders fuel volume which is critical for maintaining good fuel pressure when the volume demand is high. Once I got the volume issue ironed out, I hardly ever have to shift down on a hill any more while pulling the trailer. 4% grade or less, it just goes up and over.

 

The screen inside the fuel pump gets clogged, then fuel volume drops off, then the engine power drops off as well.

 

had the truck fuel pressure tested many times under load while driving all tested good especially after I changed the fuel pump and dropped the fuel tank and cleaning everything out

 

The 01 motor in the 03 truck, is that from a van? What's your oil level?

 

• Why were the injectors removed during testing and/or diagnosis?
• Did this issue reveal itself immediately after the installation of the 2001 engine or a while after?
• Do you have the scan tool so we can see what you IPR and ICP are measuring? Apparently everything is not normal as you should be able to go up a hill at 20,000 lbs GCVW.
• Most diesel mechanics are not familiar with the 7.3L any longer, who did the engine swap?
• Was the wiring harness swapped too?

• Is there a unit of measurement associated with "good"? Something like 55 PSI or more preferably.
• Are there are drive pressure or boost leaks from the up-pipes or CAC boots? How did you test for this if the answer is "no".

We are willing, eager and capable of helping you, but we need very specific information and a lot more details.

 

What makes the injectors good?

 

truck had an 03 7.3 powerstroke motor but I had some issues with that one with some broken push rods and a bunch more so I got a donor installed and oil level is perfect

 

had a rebuttable diesel shop out into in the coast install the motor, injectors weren’t taken out fuel tank was and cleaned out and reinstalled injectors were buzz tested they passed, motor passed contribution test and dirty diesel drove the truck around on a scanner and told me everything looked and was acting normal don’t know number as exact details as I don’t have a scanner my self, and last time I got fuel pressure checked I was above 55 pounds ripping around town and when wot

 

What Sous said. Need specific information if you're going to get any real help here.

 

• A reputable shop is all good and well, until they are not a reputable shop... One time I took my truck to a "reputable" diesel only transmission shop. Turned out to be a bad place to be and I went to get first thing the next morning.
• A buzz test or KOEO Injector Electrical Self Test is only a means to verify the IDM, injector solenoids and associated wiring is up to the task. Due to the lack of punctuation, your original post read as if the injectors were removed. With that said, how do you know the "injectors are decent"?
• When the fuel tank was removed, were the lines purged to ensure any debris within the lines was cleared?
• Was the fuel pump internal screen (unserviceable) inspected for debris?
• Strange that the fuel pressure was "55 pounds" ripping around town as that was the number I selected out of the blue earlier. Perhaps I should play the lottery today! What is the fuel pressure at idle?
• What about boost and drive pressure leaks?
• What about this issue revealing itself immediately after the installation of the 2001 engine or a while after?
• What about the wiring harness from the 2001, was it swapped too?
• Again, is there a unit of measurement associated with "normal"? There is something amiss based on what you have written. Do you have a data log, chart or even a screen shot of a scan tool display?
• If you don't have a data log or anything with units of measurement on it, are you able to get one from the person that does have the scan tool?
• If not, please see the link below.

Link: FORScan + FORScan Lite: Class Tutorial Q&A

Lastly, we are willing, eager and capable of helping you, but we need very specific information and a lot more details. Although, you have to help us help you. We need details, units of measurement and questions answered. Otherwise, the thread will die and you will be going right back to the "reputable" diesel shop that could not resolve the issue.

 

my fuel tank was full of mud and dirt cleaned that out purged all the fuel lines changes filters and fuel pump and went from dropping under 20psiof fuel pressure under load to above 55 60 psi or more at wot. The gentleman who installed the motor owns a shop in the coast called redneck truck parts and he installed everything and ran test on motor before dropping in, reseal and runtime to make sure everything was solid and I’m working order. Was also having these problems with the last motor but I took it the motor was hurt and down on power so hence why I dropped a donor in. As far as wiring harness I’m not sure if that was changed. And I’m going to dirty diesel today so I’ll get them to plug a scanner in to it and see what it’s reading, I’ll take some pictures

 

That would be the uphill fuel restriction valve kicking in. It is there to prevent excessive EGTs when going up hills.

Conversely, there is a downhill fuel feed valve to lubricate the cylinders while engine-braking down a grade.

</YouTube 7.3 “expert”>