I am having some trouble finding my problem. I replaced my fuel lines all the way back to the tank about 3 months ago and the truck ran fine after I changed them and for acouple of months. Now It acts just like the over flow valve is bad. It starts hard with a lot of missing and white smoke. Then after it starts it still misses for a few minutes and it also misses sometimes when I idel or come up to a stop. At speed it runs good I drove it 1600 miles round trip to New York a week ago. I replaced the over flow valve today but it seems to still be doing the same thing. The only other things I can think to try are to pressurize the fuel tank and check for leaks and to drop the tank and check the piece of fuel line in the tank to see if there is a crack or a leak in it. On the trip to New York I filled the tank in the evening and the next morning it started like there was no problem. That is one reason I think I need to check the line inside the tank. If you have any other sugestions let me know. I want to fix it before I get called out on another job out of state.

 

Check fuel pressure.
Instructions> http://www.cumminsforum.com/forum/94...-12-valve.html

 

Im in the process of geting all the parts together for a fuel pressure gauge. I am having trouble finding a needle valve with 1/8 npt in and out. Thanks and I will let you know what I find.

 

I am going to update this thread because many times people get there trucks fixed but do not post what they found wrong.
I installed a fuel pressure gauge and found I had only 20lbs pressure max under full acceleration it would drop to zero. I was suprised because I changed the fuel filter only 20,000 miles ago. So I put a new filter in and at idel I still had 20psi but at 2200rpm I now have 30 psi. Under full acceleration it is at 20psi. I am not sure if this was the cause of the hard starting and missing at idel but I will find out in the morning when I see how she starts after sitting all night. I will update tomorrow.

 

Ok the new fuel filter fixed the problem. It just goes to show you not to take anything for granted. I have 20k on the old filter, I usually get twice that . The good thing is it motivated me to install a fuel pressure gauge and future problems will be able to be diagnosed in minutes. I will have to say that this is one of the most important gauges to have on your diesel.
I must have gotten some dirty fuel and will not be surprised if I have to change the filter again in a short interval.

 

I've had a flakey lift pump cause similar drivability / stumbling issues.