My 94 with 196,000 on the clock started idleing around 500. I changed the fuel filter and no change. Today after getting off the freeway from a 30 mile drive the truck acted like it wanted to die. Running very roungh at idle now with a idle speed around 350-450 rpms. Seems to be running fine at upper rpms....... And my fuel mileage had droped from 21 highway to around 16 in a week. Any suggestions? And should I stop driving it?

Thanks.....

Dave

 

I would try bumping the idle back up a little. I dont recall hearing about one slipping, but I guess it's possible.

Was it all just sudden drops in idle speed, with no other real changes?

 

I thought about bumping the idle back up. But I went out to my truck tonight and raised the RPM to around 1400 and the truck is still rough. If it was a V8 I would describe it has running on 7 cylinders? Maybe a bad or dirty injector? It definately seems like it is starving for fuel?

Thanks....

Dave

 

Always start with a new fuel filter, and check the air filter. What color is the exhaust when you throttle up to 1400 or where ever it runs rough? Black exhaust means its not getting enough air, and gray/white is timing or a cold cylinder. Possible causes are low compression or a bad injector.

 

Fuel filter was changed last night. Air cleaner is new. Mt. Ram I am leaning towards injector since it happend so fast. So now to the injectors. If I am running a 10 plate, with a 3K spring kit. What size injectors could I move up to?

My exhaust is always dark grey to black. Truck seems fine on the freeway. But at idle it idles very low and very rough.

Thanks.....

 

You can do the "cutout test" to isolate it to one cylinder- losen the injection lines one each time as if purging air- if there's no change in rpm for one cylinder you've got the culprit. If you have just a little change in rpm on one cylinder (less than on the others) look into the valve lash on this cylinder. (It's always a good idea to have them adjusted properly)

HTH
AlpineRAM

 

first get ur idle to 700-850 asap....2nd check to see if ur fuel shut-off solenoid is coming up fully and staying up and check to see that the wire from it isnt corroded or exposed....that may be ur answer...if it runs fine at upper rpms then u can pretty much eliminate injectors or compression as a problem...ur idle is just wayyyyy too low i have no idea how ur truck DOESNT die ...

http://www.dodgeram.org/tech/dsl/adj...d_Gen-Idle.htm

 

Fuel shut off is working fine. Truck runs rough through out the rpm range. Idle is between the 500 and 750 mark on the tach. Smoke is still dark grey to black when accelerating.

What are the symptoms of a injector pump or lift pump failing??

Thanks.....

Dave

 

The symptoms you describe would lead me to look at three possibilities. The first is a bad overflow valve. The 94's came OEM with a one piece overflow valve that generally failed in the first few years of operation, however I have seen them last for a number of years before they fail. Second on my list would be a perforated diaphram or bad seal on the pressure line for the AFC which would be keeping the lockout arm from retracting which will not allow the injection pump to properly fuel. The third thing I would check is slipped timing. When the timing slips down below 9 you will lose idle speed and the rig will run poorly.

When the transfer pump fails you will most often run into starting problems and/or low fuel volume and no power under load.

The P pump itself seldom fails, and when they do you will generally have a slapping noise in the pump or the engine simply will not run. That can be different if the fuel stop (fueling plate) has been removed by someone that does not understand how the pump functions, as then the pivot for the fueling rack control arm will break and the engine will only develop about 40 horsepower.

 

Check that the line to the wastegate isn't melted.

 

I had a proublemat idle truck died and cranked a long time befor it started read this it might help
https://www.dieseltruckresource.com/...d.php?t=114939

 

Pittom can you tell me where the return line is so I can try your suggestion?

Thanks....

Dave

 

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

 

I went out to my truck and could not find a rubber return line. I found several hard lines in the same place that the rubber return line shoulb be?? I started the truck and it is still ideling around 500-600 RPMS. Truck runs rough until 1200 rpms then smooths out. Truck runs smoooth from 1200 tp 3000 RPMS while parked. Also truck drives fine after 1200 RPMS.

Also it seems to be taking a few seconds longer to start.

So from this info what are all the things that could cause low RPM run problems and longer time for starting?

I have installed new fuel filter, two red top batterys, and new air cleaner.

Thanks for the help guys.....

Dave

 

In red