I have a 1999 24v...low pres. pump recently replaced with FASS pump due to would not fill bowl at all after cycling key.. in-line filter installed also..came with pump..pumps putting out a constant minimum of 8psi under heavy load and 14 under light load...drove truck 1 week and started shaking furiously when touch accelerator...wud idle fine...let it sit a week..cranked and drove for 3 days..started bucking and shaking again..put a fuel pres. gage on it and drop for 50 miles with no problems and that's how I know press. on low side has been stable..drove truck this am with no problems..cud this b air getting sucked in through inlet side of tank line feeding pump or is this a probable high press. pump problem..mechanic I use don't isn't sure its a vp44 problem..truck has a bottom of the line edge on it...everything else stock..pushing 75 extra horse

 

Welcome to DF. Post this in the Diesel section, folks there should be able to help you out.

 

Is the check engine lamp on? Because you may have a misfire problem. I have seen a valve spring break or a rocker fall off the valve spring.

 

No engine light....this is a 24v cummins...did however go get codes pulled and had the 216 code which means hp pump is not producing what its suppose to but I read that if their r no other codes other than the 216 than the pump is old but ok...definitely not the pump is what the forum i read said...drove it for another 8 hours stuck in the recent snow in Georgia 2 days ago and then let sit for a day...it cranked,ran 5 secs, went dead..now want crank..still producing good low side fuel pressure of 14psig while cranking...????