W.O.T. stumble

[DavidD]

I have a syou can see below a 98. 5 24V. I have had a va box, BD exhaust, 4" exhaust system, and 275's for about 2yrs. The only problem I had till recently was from the stock clutch at 92K mi. I had just switched from the VA box to a EZ Comp. WOW! it really goes but so did the clutch. South Bend fixed that but now at wot on a setting of 3 or higher at about 2300RPM's I get a stumble, feels like no fuel. At lower rpms no problem. I dont use 3-5 on the box very often usually just to have fun. My lift pump is original now with 112,000mi. i does work as I can hear it run and shut down after a bit. Two questions, i beleive its the pump and i can get one from Cummins in Reno but should I do that or replace it with something else? Is there a dif. between the pump Cummins has and the Dodge dealer? and where is the best place to buy a gauge? Going to do that as well , help form you pump gurus would be appreciated! Thanks Dave

 

[15w40]

My guess is it's the lift pump. They die a slow death, putting out less pressure. With the mileage on your truck and the comp box, your pressure could be negative at WOT. Do a search on lift pump and sit back and read for several hours.

 

[HEYBOSS]

Check out this thread



Hope it helps.

 

[LSMITH]

The first thing you do when you have ANY sort of problem that appears in the higher RPM on a diesel is change the fuel filter if you do not have a post filter fuel pressure reading. The second thing you do is check the lift pump pressure if it is a 24V. If these two steps do not identify the problem then the troubleshooting begins. Fuel pressure on a 24V and filter on all diesels should be a reaction rather than a checkpoint when problems are in the upper RPM. Filters are cheap and if the system is in good shape will fix most problems. Get some fuel pressure readings and let us know what they are.

 

[Mopar-muscle]

112k miles on your original lift pump and you get a stumble at WOT , change the pump , and your banjo bolts .



just went thru this the other nite , truck running fine , a 99 with 114k miles , changed banjo bolts ,we couldn't can get it to prime to save our lives. even ran a short line into a can of fuel and nothing .



swapped out the pump and it fired over within minutes , and this was with the fuel system completely dry , empty fuel filter canister.



put a carter 4601HP back at the tank , extended the factory power directly to it .

 

[Steve Campbell]

IMO, Mopar's last sentence is THE fix.

 

[DavidD]

Thanks for the replys, I will change the lift pump this week. I have a fairly new(sept. ) fuel filter in there but will change it anyway. hanks for the tips! I let you know how it works out, Dave

 

[DavidD]

Give credit due where credit is due! L Smith posted a reply to this thread and suggested i change the fuel filter first. i had just changed it in Sept. and coulnt imagine it bad already, WRONG it was filthy. Just about black with gunk. i cant figure what except a bad batch of fuel. Truck ruins great now and no stumble at full throttle. Thanks for your advice L Smith. Dave D

 

[LSMITH]

Hey Dave, glad I could help and you are back in business again. That is what this is all about. Take care, Howard.

 

[GGades]

Dave. I've got a 2001 with the same problem. With the comp box off there is very little jerking, turn the box on and it gets worse from there as you increase power levels. I don't believe it's a fuel problem in my case, i've got10-11 psi at wot. The problem starts right at 18 psi of boost and stops around 25. I think it may be a software glitch between the comp and the ecm :-{} even with the pump wire and the data port unplugged the problem is still happening. I talked to Arron? at edge products but didn't really have an answer, but we are trying a new box and harness. I had a Banks Power Pack on before the comp and never once had any trouble but the banks did not work with my DDIII's at all. Had plenty of power but just could not maintain a steady speed with the pedal and cruise would not work at all! Anyone have an answer to our problem I'm all ears and eyes I'd suggest calling edge products and talking to Arron, he was vere willing to listen and help. If others are having the same problem the boys at edge need to know.

 

[LSMITH]

Ggades, if you are having the problem with the data link and the pump wire unplugged the problem does not lie in the Comp or it's harness, your problem is in the truck somewhere. I do remember a post by Steve StLaurent about a somewhat similar problem and his MAP sensor or connections were not good. Swapping your MAP sensor with a buddy would be quick and easy to see if it is the sensor. Steve mentioned a clicking in hte injection pump with key on and engine not running when wiggling the connectors to the MAP sensor. There have also been a couple of guys that had what you are describing and the injection pump was replaced fixing the problem. The only other thing I can think of is the APPS signal is not clean, sending erratic signals. You can watch the output of the APPS with a graphing mult-meter or an ocilliscope and determine quickly if that is the problem. The Comp box is magnifying the base problem in your case.



I would suggest a post describing your problem to get the input of the guys that have had a similar problem and also searching for "bucking" and "stumble" as I remember those words in the posts to describe the situation. Hope this helps.

 

[DavidD]

Gades, i agree with Howard again! The comp box cant be bad if it still does it with the fuel wire off. I would check and clean your map connections. You could be getting a pulsing signal through the map. I talked to a guy( forgot his name) at Isspro the other day and he said at that same boost on mine I get a rattle in my boost gauge, caused by pulsing in the intake plunium. This could be makeing you map sensor go wacko?and sending that to the ECM. Did youu check your fuel filter anyway? wouldnt hurt, Dave oh Good luck I know how frustrationg these little problems can be.