"stumble" ?

[Blake]

Hello folks,

 

I have noticed when I go to start my truck after a day or two of it not being ran it will start right up..but the minute I put it in gear (forward or reverse) and push the accelerator it will.."stumble" like it wants to die but just the RPMs drop and go back up. This probably goes on for about 10 seconds. I tried search but I could not find anything..though I swore I read a thread about something like this long ago. Any input is greatly appreciated!

 

-Blake

[Darkanion]

Sounds like it could be a fuel pressure problem to me. I'd check the fuel filter first. If that doesn't do the trick, it could be the fuel pump.

[citori man]

ya in my old truck it started to run like crap and would stumble everytime i pressed the gas and i replaced the fuel pump ran good as ever

[Blake]

Not what I wanna hear lol But thanks for the input guys !

[kgrigsby]

Hi There was a service bulletin regarding this problem from GM awhile ago, it involved updating the pcm, with a new program.

I found that my 99 4.8 would do what you describe on ocassion, so I just disconnected then re-connected the battery for 5-10 minutes and have not had a problem since. (you are just rebooting the pcm ) So give that a try before buying a new fuel pump. If the fuel pump was faulty the engine it would continue to hesitate when a high power setting is demanded later on. If still not sure, borrow a fuel pressure gauge and check for pressure drop at the time of stumble, you should be 55-60 psi.

If that does not help see if your local GM dealer should be able to find that Service bulletin for you.

I find it is cheaper to spend money on diagnostic tools and manuals instead of changing parts until what ever the problem is goes away, were I live GM charged $110.00 hr shop time. And Parts, you would think they where gold plated, but that is the way it is. Good luck!

[Blake]

I will try your suggestion(s) and see what happens! Much appreciated!