Here is what I have done to try to correct this problem, yet im still loosing the battle.

New Fuel Filter
New Fuel lines from tank to prefilter
New Rubber line from prefilter to lift pump
New Lift Pump
New Prefilter and seals
New Overflow Valve
Replaced pickup tubes, with draw straws
New Injectors
Valves Adjusted


It idles rough, and if it idles for more then a few minutes will puff white smoke when I take off, It does not use much oil 1 quart every 5000 miles. The warmer it is outside the more noticable the rough idle is. I have tried pressurizing the tank and found no air leaks. Starts fine, runs great, i just want to fix whatever is wrong. Whats next?


Dave

 

Sounds like the pump timing has slipped. You will have to have special tools to reset. Do a search for slipped timing or timing tools.

 

Forgot to mention Timing was set when first thing after i bought, then rechecked about 9 months ago. So I dont believe timing is the problem, I knew I forgot to mention something in my post above, I have exhausted myself trying to think of what the issue is.

Dave

 

if the timing pump shaft got oil on it it may have sliped time a little bit...just a thought

 

The performance diesel shop by my house listened to it and his thoughts was it was the valve train, possibly a sticky valve. Why would cause it run worse the warmer it is outside, in the winter when it really cold outside it run quite smooth, as soon as it warms up above 50 degrees or so it gets rough at idle.

 

bad injector maybe??

 

Bad injector or pump timing

 

Im going to crack the injector lines tonight and see if i can narrow it down to a single cylinder, I was looking over the engine today and the blow by tube has a constant steam like vapor coming out. Like I said, its been having rough idle issue for about 2 years... Since then its been timed 2 times and I just replaced the injectors about 4 months ago with no difference. I did notice that if you rev the motor in nuetral when it comes back to an idle, it will idle worse for a second or two, almost sounds like a miss, then just idle rough, when i say rough i mean it shakes the mirrors and the 4 wheel drive shifter. Two of my buddies have 12 Valves and theres both idle considerably smooth. The idle on mine is set at 800 in gear/ac on.

Any thoughts to diagnose the situation, im all ears.

Dave

 

::Update::

I just cracked the injector lines 1 by one, I couldnt pin point any single cylinder, however when i cracked the line the bubbled fuel, #2 seemed stronger then any other one and would squirt to the hood, could be because it was the easiest to loosen? I dont know if this tells anyone anything?

Dave

 

when you popped the injectors did you check your valvetrain adjustment? Perhaps you sould check your valvetrain clearances.

 

Hope you get your beast running ok....did you get your dent fixed in your truck?

 

12ValverDave, I have a 95 3500 5 speed that's doing the same thing as yours, and been doing it a couple of years. I have replaced injectors, and done some other things to it, but nobody seems to know what to do..........if you figure yours out let me know what ya done.....................
Barry Franklin

 

Id check for boost leaks by pressurizing the system with a 4" PVC pipe cap and an air chuck.
Then maybe check the flow on that vent tube. cummins recommends checking the flow on the vent versus individual compression tests it seems. if there is too much pressure you might have a bad vacuum pump thats pressurizing the crankcase, or it might be a real compression problem.
You may want to at least try swapping your injectors to something newer if the stock ones are old. Mine were dumping piles of fuel which sooted up the oil within a few miles. Now its a dark gold color even after 500 hard miles.
Otherwise the only thing left to look at is the injector pump

 

Whats cummins specs on the vent tube? Is it in my factory service m

 

my 94 is idling bad also thought it was injectors pulled all 6 and had checked they said look elsware ,pump, cyl, or valves, im lost also still runs fine down the road but idles terrible 202000 miles,Had better luck with my old 85 dodge 318 granny low 4 speed,it had 340,000 miles when i parked it never had any major break downs Good luck.