mr.mindless

background:
'97 12v 5sp; 242k on it; got a new head less than 1000 miles ago. Just removed the fuel plate and adjusted AFC for light smoke; waiting on DV socket to arrive in the mail so I can check and adjust timing. no fuel leaks that I can see anywhere under the hood. low and high pressure lines are dry. no water in fuel light. old fuel filter, don't know the last time the screen was cleaned, unknown history on overflow valve, injectors also probably original.

Pulled with it about 70 miles yesterday morning. Ran great no issues. Started it up about 8 hours later for the drive home and it started and idled great. let it idle for about 2 minutes and went to pull away, and it hesitated. Tried again and same result. No load it would rev to about 1800 and then start missing and blowing white smoke. I looked around under the hood for any fuel leaks or evidence that I could have had air intrusion and found nothing. Fuel tank showing 3/4 or so, and have not had any issues running it under 1/4 indicated, I think the gauge is accurate.


After about 5-10 minutes it magically cleared up on its own and had NO further issues on the 65 mile tow home. EGTs in the same place they usually are, power where it should be, ect.

At the time I was thinking fuel filters. We didn't have a new filter when we did the head so the old one went back on. Didn't clean the screen in the heater bowl either. I don't have a fuel pressure gauge on it and I don't have a 1/8" NPT tap to tap a banjo and put one on. I should be able to borrow one this week. I ebayed a Bosch overflow valve last night. I figure I'll get the o-ring kit and do the heater bowl and throw a fuel filter at it as well but I'm wondering if I should be looking out for a failing lift pump (that then caught up to itself?) or bad injector(s).

I'll check with my local Cummins shop and see what they'd get for pop testing my injectors and go from there on that front. I'm sure at almost a quarter million they won't give a fantastic pattern, what's the good swap? I know nozzles alone on my TDI made a huge difference with no other change simply because they'd flow more fuel for a given pressure and duration, improving effective timing by shortening injection duration for a given quantity of injected fuel. Is that similar to results on these engines? I hear of the 370hp marine injectors but also that they are meant for a different cam profile in the P7100.

I searched for missing and white smoke in this forum and didn't come up with much, and nothing that directly applied...

Thanks for any insight,

mr.mindless

Just another data point: I fired it up yesterday afternoon after about 18 hours sitting and got the same results: was "running out of fuel" above 1600-1800, and cleared up after about 10 minutes of idling when I checked it again.

mr.mindless

No thoughts on likely causes or on injectors to get?

I talked to three shops today who could not look up parts for my engine serial number. I guess I'll be calling Cummins Northeast tomorrow to hopefully get correct part numbers for the fuel filter and fuel screen and o-rings. None of the fuel system part numbers listed at http://www.dodgeram.org/tech/dsl/Facts/96specs.html checked out at Cummins and none cross referenced at Advance either.

Who knew that getting parts would be so tough? I was under the impression that with the serial number any shop ought to be able to get the full parts listing. My s/n comes up with "no parts available" or something along those lines.

infidel

I wouldn't do anything until you put a fuel pressure gauge on it.
Here's some instructions> http://www.cumminsforum.com/forum/94...-12-valve.html

Send a PM to Don Wagner here> http://www.cumminsforum.com/forum/pr...o=newpm&u=6147
for the best injectors and advice on them. Make sure to tell his what you intend to do with the truck.

mr.mindless

Lots more traffic in the 12v section over at cumminsforum. Glad to see there's still some activity somewhere.

Thanks for the pointer Bill. I sent Don a message and I'm doing more reading over there.

infidel

Lot more traffic over there but more experienced people to answer your questions here.

The crowd at cumminsforum seems to be mostly kids who just want to make smoke by gutting their AFC.

mr.mindless

absolutely a bad overflow valve. Got a fuel pressure gauge on it tonight and it's only sitting around 8psi at best, sometimes as low as 4.... pinched the return line and it's up to 40psi no problem. May throw the filters in it anyway but I'll may just change them based on the fuel pressure now that I have a gauge.

mr.mindless

stretched the spring as a stopgap. it's at 32psi now, I can live with that for a couple days. it's running MUCH better, especially at high RPMs. holding at least 20psi under all loads, looks likely that's my only issue.