How does a diesel run?????? that is burning rather lean, lean and very lean? Can anyone send me to a web site or ???? need to read up on it. For I suspect that this is what mine has been doing since new!!!! This gutless garbage. 99 24 manual. For now it bucks or pulses up to 1650 rpm. This last 300 + rpm is of the last few months. For I can't run it below 1700 in any gear. I never have enjoyed this 99 garbage of a truck. Thanks

 

Have you tried changing the fuel filter lately??? Put a fuel pressure guage on it, maybe the lift pump is going bad.
As far as a diesel instructor goes, try a local college or vocational school. If you have a specific question, just ask it on this site, you will get many well educated replies that come from experienced mechanics in the field. I have over 30 years in the field and 14 of those in a dyno lab doing R&D on experimental engines and occasionally a prototype, including combustion photography, injection development, and combustion development, emmissions testing and controls. What would you like to know?

 

Lots of good info here:

http://www.dodgeram.org/support_pgs/diesel_ix.htm

Basically you have an engine that uses compression of incoming air charge to heat the air to a point that will ignite a fuel spray injected at the proper time. The power output of the engine is mostly dependent on the amount of fuel that is injected. There is NO throttle plate. The turbo charger gives more boost when there is more fuel being injected so it's sort of a positive feedback situation. More pedal = more fuel = more boost= more power. If you're losing power look for fuel starvation first.

Regards

Edwin

 

What is your fuel pressure?
I've got 160K miles on my 99, never a problem.

 

Could very well be the injection pump is on its way south.
My '99 is definately NOT gutless. (75,000 miles)
I'd agree that the 1st steps should be a check of the fuel pressure and the fuel filter.

 

Lift pump pressure is good at 12.5 lbs after filter and 9 at WOT. With mine more throttle and more travel DOESN'T MEAN MORE POWER NOT IN 1 ST , 2ND AND 3RD GEARS A FEW LBS BOOST. 4th will get you boost and it labours hard if you put your foot into it. I loose about 900 rpm in shifting so even at 3000 it really has to work. So back to my questiuon how does a diesel run that is running in the lean zone. will it want to shut it's self down as it turns over???? The new injector pump the other year made no difference on the lack of performance.Just made my wallet lighter. Everything so far hasn't made it run the way it should!!!!!!!! Air& fuel filters MAPS,AIT, CKP, lift pumps, injector pump, new injectors, RWSS PNP ,ETC. So as you pass me be kind for I can't get out of your way. Ran a Ford 1/2 ton the other day and spun the tires on dry pavment. Not used to that kind of power boy was I embarressed!

 

Just for giggles, have you had a REAL Cummins shop look at it?

 

Sounds like you need to get it checked out. But first thing is that diesels do not run rough because of being "lean". The fuel and air are not mixed and then burned as in a gasser. The discussion of rich and lean is kind of useless. Only when running at full power do they begin to run rich, and only then if chipped or starving for air. You have another problem and it sounds like an electronic one. A clogged fuel filter will show up at higher power levels first, not when lightly loaded at slow speeds. Your seems to run OK at higher levels so I doubt if it's a filter. Maybe a suction side air leak.

I'm surprized you think your truck is "garbage" because it's got a problem. Get it checked out and see how great Cummins' are.

Wetspirit

 

Got part way through the post but, As said if your runnin low power, its a lack of fuel problem. Not really a lean though. Diesels dont run lean or rich, not like a gas engine that mixes the air and fuel. Not sure on the 99s, they might not have the brains to control it but if your not pullin in the air it might not give you the fuel, I mean if your not having smoke issues youve got plenty of air, but it might be detecting the lower air charge through emmission testing?!? i gues im not sure how the 99 works

 

Sounds to me as the internal timing mechanism in the pump is bad. Supply side restriction can cause this as well as the timing mechanism in the pump itself going bad. This problem will usually log a Cummins fault code of 368 "VP44 Cannot achieve the desired timing". When checking supply side restriction, hook a vacumn gauge up to the inlet port of the lift pump and monitor vacumn. At high idle the vacumn should not exceed 6inhg.

 

When a diesel is running without a load you control the amount of fuel injected into it to control its power output. The cyl takes in a full charge of air on each intake stroke and compresses it, then the fuel is injected. At a no load condition it will run at around 75:1 A/F. In diesel language it is not called running lean. When you want to produce power, you increase the fuel injected per stroke to produce the desired power. The A/F will vary according to the amount of air drawn in on the intake stroke. A turbo will pressurize the intake and pack more air into the cylinder so you can inject more fuel to produce more power, when designed correctly and calibrated, you can double the power output of a diesel with a turbo and not produce much smoke out the tail pipe. The smoke you see from the tail pipe will start around 20:1 and keep getting blacker the richer you take the A/F, but increase the air charge with the same fuel, the ratio leans out and reduces the smoke output.
I hope this gives you a better understanding of how diesels run without getting really long winded. You may have an air intake problem or turbo, or map sensor, or leaks on the inner cooler or a restricted cooler. Bst way to tell is by putting guages on it to monitor the pressures and delta pressures so you know where to go from here. If you keep guessing and replacing parts that are not the problem you will always remain unhappy. Always test and diagnose the problem before you just replace.

 

Thanks Hemi cat. Need to be able to read the answers to be able to answer them. With having no codes cryslerr says that there is no problem. The diesel tech at the dollarship[ said years ago that 130 out of the 235 was about right for RWHP .Not sooooo. says I. If the ecm doesn't see an off-idle change of state will fueling be at idle? If turbo is stiff (not be able to spin readily) what would this do? Should still fuel but not to what it should be right. How much should they spin for proper operation?

And yes I have taken it to cummins shop and that was a great waste of money. With the breakout box it did sound different and not the clatter of valves that it normally does told the mechanic this and he said that it starts and that is all that he can tell from this not that the isolation of ( ????? parts ) makes the engine run the way it should . Have talked to the manager since and he says that I still have ongoing problems that I need to address. Talked to another shop and did get some info on Group 19 Electronic Engine controls On the Validation Switch (IVS) . These numbers are not what I measure so am more confused then ever.and he said that he sent someone that wrong direction and cost him ( the owner) money. What else have I not answered???
So far nobody can talk to me about fueling. THERE IS NOOOO INITIAL FUELING VERY SIMPLE. I have a good idea and know more than they seem to know. But somebody has to convince me that they know what they are talking about and have a very comprehensive plan before I waste any more money on this junk.

 

does it run alright? Could be air in the fuel, How many miles does it have? Could use some valve adjustments, There are a few mechanical things on the 24vs that can be addressed. Do you have any smoke? THat would show you what way to head.. air or fueling problems. If you have more than normal smoke could be air, If you dont then obviously fuel.

 

Sorry not valves.Never has run the way a diesel does! It doesn't idle properly and thumps when it does. One has to start at the very technical and go from there! When you give it throttle it rev's and screams but you DON'T get more power! No boost in 1 st , 2nd a few lbs in 3 rd and 4 th after 1600 it picks up but labours to do so.

 

No don't get smoke either. It isn't burning fuel to smoke