Engine/Transmission (1994 - 1998) Stalling when stabbing the throttle

[JeppinHackSaw]

Stalling when throttle stabbed, updated w/ injector (maybe) miss

98 12V, EDM'd 370's, stock plate just shy of full forward.



Put the injectors in last night, the problem was always there, if you blip the throttle and let off quickly, the truck will stall or stumble.



It always did this before, but not as easily (most of the time just if the motor was a little on the cold side. )



Now, with the addition of the injectors, I can do it if the truck is warm.





Is this the culprit of an air leak somewhere in the fuel system or what?

 

[JeppinHackSaw]

Another thing...

It misses at certain RPMS (just realized this)


If you put it in Gear and hold the brake and accel pedal @ about 1100 RPMs it shakes and shudders, also at about 1800, 2200 and about 2700 (trying to throttle out of it)

EGT's don't do anything different when this occurs nor does boost fall off.

I tried bleeding the heck out of the injector lines... cracked each one and left it cracked for a minute or so...

The only thing that I did during this upgrade was to install the injectors, the truck ran pretty well before doing so... could air be getting into the return lines? (I noticed one of the copper 'washers' or whatever you want to call them on the return lines was a little messed up, I bent it back into shape and tightened it up. . there is no fuel leaking from it. . but could a smidge of air be getting IN and causing the issue?)

I am guessing that both of theese problems are related... I would REALLY like to figure this out, I just can't get any parts tommorow (sunday) at any of the shops around here because they are all closed that I know of. . unless someone knows of a cummins parts place that would be open in southern Michigan (oakland county preferably) or someone that would have some of thoose washers laying around... Or if anyone in the area (I'm in the pontiac/waterford area) would be willing to take a gander at it for a better opinion that would be awesome!


Thanks!

 

[DBraunig]

Have you tried adjusting the idle for the stalling? what rpm does it idle at now? If the idle is right, one click on those governor springs should cure it. Did you put the gsk in your sig in the truck too?



I picked up that stumble your talking about when i put in 370's. The only way i could cure it was a set of 191 delivery valves, smoothed it right out . Did the stumble/misfire start after you changed the injectors?



Dave

 

[JeppinHackSaw]

The misfire/stumble deffinatly started after the injector install.

I didn't touch the GSK yet, I wanted to tackle one thing at a time so things would be easier to diagnose if something went amuck... which it has.

Truck sits and idles about 850 RPMS, about 800 if I hold it in gear and stay on the brakes, which is correct from everything that I have read.

 

[K5IP]

perhaps a bad injector?

 

[CBeeman]

These are just my thoughts. Like he said check your idle in gear should be about 850 mine is closer to 900. The return lines that you are talking about are on the presure side of the fuel system so if there was a leak there it would be external. And your stumble/miss i would but get a set of delivery valves. 191's should work well. I have read about this type of problem with 370's and stock dv's. Hope some of this helps

-Chris

 

[RWorth]

These are just my thoughts. Like he said check your idle in gear should be about 850 mine is closer to 900. The return lines that you are talking about are on the presure side of the fuel system so if there was a leak there it would be external. And your stumble/miss i would but get a set of delivery valves. 191's should work well. I have read about this type of problem with 370's and stock dv's. Hope some of this helps

-Chris

I think the stumble dealing with 370's and dv's were on the '94 160 hp pumps.



A friends truck was stumbling and putting out a blue/gray smoke. The truck would idle just fine but when loading up trying to get uo to speed the motor would stumble and miss. I replaced the fuel filter and things cleared up. Have you checked the overflow spring. Just a thought on the fuel filter and overflow.