Hey guys I need help diagnosing a problem in my p7100 just barley took my 1996 12v auto 4x4 out for another drive and this is what I came up with it still starts idles just fine I put it in drive or reverse it idles hard I give it throttle to get up my drive its I little boggy And smokey get to the first stop its idling hard while I'm on the brake takes off fine just smokes once I'm goin I can build 18-20psi boost pyrometer is between 400-600 truck shifts nice and builds its boost the same I get to the stop to the highway and its idling rough again once I'm going its smoking but building boost and once I'm going around 35-40mph its running like a champ building boost up to 30psi with my pyrometer between 600-900 I really don't think it's an air problem the mechanic I talked to is a good one and said its my injection pump I just need to know if I can replace certain parts and fix it or if I have to replace the whole thing?! Any advise would be great thanx

 

What color smoke do you have coming out? Does it idle rough even in park? Any mods like spring kit or fuel pin?
It maybe an injector.
once the RPM's build the miss isn't noticeable but its probably still there. Is fuel economy down?

 

It's a black grayish smoke it idles just fine in park or neutral and everything as far as I know is stock and the economy isnt really that different

 

How many miles on this beast?
I would pull a compression check and borescope the cylinders then install a new set of injectors if the cylinders look good. The 7100 pumps are a good pump and you don't hear about them going bad that often.

 

It's not the block maybe injector but it's not my block the mechanic at the local cummins shop told me it's the p7100 he's a good mechanic does lots of good honest work I just need to know if there is any certain parts I can replace to fix the problem

 

I meant cylinders /block some one mentioned timing to me but I'm sure the mechanic would have caught that

 

I would NOT be considering the pump unless you have truly exhausted all other possibilities. I worked at a Chrysler stealership as a graduate of UTI auto/diesel/performance program, was not allowed to work on Cummins trucks because their "experienced diesel guy" had everything under control; first replace the injector pump, then replace injectors, then troubleshoot if it comes back.

Do not expect that anyone has checked the timing, diesel timing lights are expensive and manually checking requires taking injector lines off and using a degree wheel. What is your outside temp, what is your engine temp, is your fuel blended/rated for cold, does your intake heater work, is your waste gate connected, have you replaced your fuel filter, what rpm are you getting said boost psi, has your charge air cooler been checked (replaced my perfectly good one two years ago because it had over 20 pin holes that could not be seen)?

P7100 pumps are good for 500k-1 million miles if treated correctly, it is probably not your pump.