I have a 2007 5.9 cummins in a ford f-650 rollback. The truck has never had a programmer on it, has had the turbo rebuilt, no power adders of anykind. I dont think the fuel screw has been turned up.

This truck smokes black from the minute you crank it up to the time you cut it off. And no one has a idea what the problem is. It has no code showing has the cat with 4 inch exhaust. I have been told it may be a boost leak. Fuel pressure jacked up. Or the fuel could be fine and the truck not getting enough air. But idk what to do to check and fix it or even start after the basics.

Any help will be appreciated.

 

Where is the fuel screw on a 2007?

 

Greetings! Maybe the cummins is protesting being in a ford....Just kidding! Jacked up fuel pressure in an unmodified 07 throws me. Definately check for boost leak ie: loose clamps, ruptured boot(s), worn hole in a boost tube/pipe. Maybe major restriction in the intake side such as clogged air filter or or other restriction. Turbo working ok? Making boost? Plenty of power or sluggish? How's your exhaust temps?? You mentioned the turbo being rebuilt. Check the bolts where the turbo mounts to the exhaust manifold. Make sure theyre tight and youre not losing exhaust pressure (exhaust leak). Look for black sooty residue in this area. Make sure your exhaust manifold bolts are tight as well. When was the fuel filter changed last? Im sure there's more but my brain is mush right now. Long day....

 

The air filer ever other oil change. Fuel filter ever other. As far as power low end is sluggish. But when the turbo spools it moves on exhaust temp idk no warning lights.

Ill check the tubes clamps bolts and piping in the morning.

Thank you and if you think of anything else please let me know.

 

Does the engine run hot. (gauges or idiot lights?) Im assuming you dont have gauges to monitor EGT, turbo boost, trans temp? Im also thinking stuck open injector(s). Happened to me at 65k miles. 4 out of the 6 were stuck open. Have you ever noticed highter than usual oil levels on the dipstick? Diesel fuel smell in the oil when changing it (indicating oil dilution from excess fuel)? Overfueling comes to mind if you have the above listed issue. Im not exactly sure if a stuck open wastegate would cause your problem. Im hoping someone chimes in with this past experience.

 

To the first 4 questions would be a no. I had diagnostic service pulled and had no engine codes. How do i find out about the iinjector? I can not find a boost leak. Im serviceing the truck this week. So i can find out then. It builds boost great. So i dont think its the waste gate. But I could be wrong.

Thanks for the ideas

 

Im am now officially STUMPED!

 

Dont feel bad bc it has been stumping the guys at the cummins place for a year. Im just tired of there guessing and guessing and never getting anything fixed

 

Sorry I wasnt much help bro.

 

Was this happening prior to the turbo rebuild? If no then I would start there and have them remove the turbo and either replace or confirm that the turbo rebuild is in the specs. required.