Hello. I'm new and need help. My 96 Dodge 2500 5.9 is cruising nicely down the highway when all of a sudden it starts to shudder and buck . When I try to accelerate it bogs down then it shudders and climbes in rpm. I get off the pedal and it holds the rpm higher for a second and then goes down to stall. I crank it over which requires more that usual and it starts and continues to run rough and do the same. If I park it and try later it will run like a champ for an hour and the whole thing starts again or sometimes it just goes away only to come back. I have added fuel conditioner and changed the fuel filter. Please help me and my baby Thankyou.

 

could be air getting in the line. do you have a fuel pressure gauge installed?
I installed a furnace sight glass from mcmaster-carr on mine in front of the lift pump so I can see any air thats pulled on the vacuum side.
could also be the fuel solenoid limiting fuel.. is it working and adjusted right? maybe secure it in the up position as a test?

 

Could be your fuel tank vent as well. Try leaving your fuel cap loose and see if it still does it. Did you check the pre-screen in the pre-heater when you changed the fuel fitler? If not, that's another thing to check.

 

Install a fuel pressure gauge and see what it does when the engine is acting up.
Instructions> http://www.cumminsforum.com/forum/94...-12-valve.html

My bet from what you describe though is that one or more of your injection pump plungers or bores is warped and the problem is heat related.
To check this out pour cold water over the injection pump when it acts up then see if it cures it for awhile.
If it's the cure then your pump needs rebuilding or exchanged for a rebuilt.

 

Bill hit the nail right on the head. Most cases you turn the engine off even for 1 min, it cools anough and runs well again until the plunger sticks in the barrel under excel. Get it looked after sooner than later or....

 

I do not have a fuel pressure guage. I will try to get one in. I did loosen the fuelcap previously with no sucess. I had a local garage put in the filter so I don't know if the prescreen was checked. Maybe I can find out. The temperature here is well below freezing. This morning when I fired her up...purred. I left for work and after 40 min of running nothing happened. After sitting all day in the cold, as soon as I started her, the game started and persisted all the way home (40 min). This makes me wonder if the temperature and plungers are an issue. I think I hear a clicking or tapping sound under the hood when it is acting up. It goes in sync with the engine but I'm not sure it's there when she is running right.

Still confused...appreciate your thoughts.

 

A fellow suggested to me it might be a cam or a crank sensor being intermittant

 

Not on a 12valve bud. The only electrical component on that engine that it needs to run is the shut-off solenoid. That's the beauty of the mechanically injected diesel converter!

I should be more clear: it doesn't have a cam or crank sensor....

The clicking sound may be the lift pump. They can go tick-tick-tick when they are worn, but generally it's only noticeable at idle.

 

Could it be his fuel shutoff halfway closeing? Reason I ask is when deer hunting I was rolling down a steep hill in 1st and I turned my key off to quiet the engine but kept it spinning for brakes and stearing, when i turned the key back on the engine would not come back to life normally like my previous diesels and gassers do, I swear it only ran on 2-3 cylinders no matter how much throttle I gave it. After a re-start it ran nomral.

 

Good of you guys to be patient with me. I am a machinist/fabricator by trade but have had very little engine knowledge/experience. Here's the interesting part. I have the means to have whatever truck I desire but when I laid eyes and ears on my old 96 three years ago something special happened. I have never been so fond of a truck. I live in Kenora Ontario where it seems a real diesel tech is non exsistant(Manitoba boy originally) Enuf bio, my point is that it looks as tho I will have to get down and dirty and do some of my own mechanical. I likely wouldn't consider it but the 12v is inspiring.

I need to check this but I think the truck has a "kit" on it to eliminate the lift pump. So far I kinda like the fuel shutoff solenoid theory. Can we say that the problem is not electrical ? ie in the "brain". So far it's sounding like if I changed the injector pump and the fuel shutoff solenoid, it may be over.

 

Ah, bit by the old 12 valve mystique?

I'm in the same boat, plenty affluent to buy the latest truck, refuse to because they have no soul.

You had better hope like heck somebody didn't put an intank lift pump conversion in there........ I don't think even the dumbest dealership would pull that one, but you never know. Look right in front of you fuel filter, slightly below to see if you have a block mounted pump with either a black rubber bellows or a white plastic hollow stem ( rubber boot is rotted off ) BTW, that button is how you prime your engine after a filter change. That is your lift pump, and bolted to it is a bracket where your fuel heater and pre-filter screen resides. It sounds like you haven't checked and cleaned that ever. That would be my first investment of time and money, get the 8 dollar pre-filter change kit and replace the screen and seal. After that, see what you have. Checking the fuel solenoid is super simple, with it running, just try and push the lever up further. If it moves further, then get a new boot for 15 bucks or so from Foster truck, take it off, clean it good, put the boot on, and drive happy.

Don't just start changing parts just yet........

 

Great info....I'll check today

 

So I'm learnin fast. I definately do have a transfer pump. Boot is in good shape. Started her up and tried to push the fuel shutoff soleniod in farther and it didn't budge. I suppose that can be strickin off the list, although the "thing" wasn't happening at the time. Either a solenoid works or it doesn't right? I know where the prescreen and fuel heater is now and will see if I can get a prefilter change kit ordered. Looks like a ***** to get at from the top, maybe I'll lie on the driveway and see if I can get at it. I assume there is a bottom hex to loosen and the "cup" will drop down. I am hoping the solution is getting closer. BTW after a cold start yesterday and a 40 min drive with all symptoms going full blast, this am's cold start she seemed to run good.

 

So does anyone have a part number for the prefilter screen and seal ? Our parts store seems dumbfounded. Thx

 

Tapping is normal with a warped plunger that's stuck. It's the injection pump camshaft hitting the bottom of the plunger.

Couple links for you:
http://dodgeram.org/tech/dsl/filter/pre-filt_clean.htm

http://dodgeram.info/tsb/1996/14-07-96.htm

I understand your love for the 12 valve. It's the last vehicle sold in the US without a bunch of smog crap.
Simple is good.