My 6.2L stalls when I let off the gas pedal...Help..Please.
 

So the history goes something like this,
84' K20 4x4 N/A 6.2L diesel, My baby. Donor vehicle is a 82' 6.2L 4x2 that has been " rebuilt " 2 1/2 yrs ago.
I pulled my motor and replaced w/ the rebuilt.
She sounds strong and I even drove her around yesterday, a bit.
Problem is when I let off the gas pedal she stalls.
When I ease off the gas pedal she will NOT stall.
Any help would be greatly appreciated.\
Whole job took me about 20 hrs...no book, no manual, and with very little help.
I am a residential contractor that found myself taking on the projct my self....learned alot and I am a lot closer to my burban.
Thanks

Need to raise the idle rpm a little bit.

Raise the Idle up a bit......
 

I turned it 1/4 over ......1/4 under .....full over and a full under no change other than not being able to start the truck.
Fuel filter?
??/??

Does it seem to idle ok?? It doesn't idle normally, then take off on it's own, then almost kill itself from too low an rpm??

Idles great...sounds great...but if I rev the engine and let off too quickly then she stalls.
I have replaced fuel filter and ....no change. If i am gentle on deceleration she is good, but if I gas it and let of she will die..........not a clue on what is going on other than throw her to a qualified mechanic.....this project has been an endeavor, now I would like to reap the fruits of my labours.

Does it fire right up every morning, or does it crank for a bit before it starts?? Also, check and see if there is power to the other set of wires on the injection pump (be 2 small green wires). If there isn't any power, run a jumper from the fuel cutoff.

Fires right up and the idle is up and down for a couple of minutes untill she warms up.
I do believe I know the two wires in reference. I will check today...thanks again for you time and assistance!!!!
:rocking:

Not a problem. :c:

Guess I will be getting fuel additives and water seperator tomorrow and see if that fixes the problem.
She was shifting late yesterday...I will see if there is any change tomorrow when I go get the additives( recommended by Mechanic friend) otherwise might have to hand it over to a certified mechanic...don"t want to!!
:s:
Oh well...onward and upward!!!!!

good luck

OK....so she is on the road..shifting a little late but feels good, but the Idle is realy high.
I messed w/ idle screw but feel like now there is no difference......I have been working on her for too long and im probably confusing my self.Oh and the stalling problem was the spring inside the fuel injection pump. She needed to be played w/ lubed and stroked....She's real nice now. Thanks again Wildbill and others.

MY 86 suburban has the same problem and its driving me crazy :argh: was the larger spring or the smaller spring within the injection pump your stalling problem and did you remove it to lube it?

There is a solenoid on the throttle that runs the engine at high idle for about a minute until engine warms up. It is controlled by a sensor in rear of right or left head(can't remember which). Have you noticed this higher idle on start? There is an idle adjustment screw going down into the middle of the solenoid. This may need several turns to raise idle speed to proper level. However if all cylinders are not running properly, the idle will drop as you described and kill engine. You should turn up idle until engine idles at proper speed then diagnose idle problems. Good luck!