99 K1500 Sub runs poorly

[noJeepshere]

My dads 99 GMC Suburban (350 vortec 4 speed auto 4x4) has an annoying engine problem. It stutters and stumbles and in general runs poorly. Having just drove it, anything over 1/2 throttle makes it stutter, anything less, and it runs ok. Cruising down the street, flooring it will make it shift (slowly) to first and then just hang out there. Nothing more. My guess is the fuel injectors being dirty, but have no way of being sure. I will pull the spark plugs pretty soon to see what they look like, and post a pic for the world to see.

Thanks for any help guys.

 

[4xcrazy]

I'm getting ready to go to a friends place tomorrow to change out a fuel pump from because of these same sounding issues, he already changed the filter, not any better.
i also had the same description of problems when mine died as well.

Change out the fuel filter first, then start think about checkin the fuel pressure if it still does it.

of course i am going to check pressure before i start dropping the tank too

 

[noJeepshere]

Here's a list of codes it had when I put the scanner on it:

P0171 both sides: Engine lean run condition

P0101 MAF sensor condition

P0452 Fuel tank sensor condition

I bought a can of MAF cleaner (didn't know something like that existed) and sprayed the MAF generously. That really seemed to help. I am looking around for a fuel pressure tester to see what the fuel pressure is. Interesting thing about the condition is that it is only real bad at first, but if it left to idle for several minutes, the problem isn't so bad Makes me believe the pump may be going. My Yukon ran beautifully until the day the pump died, then that was that, so this is throwing me off.

 

[chulisohombre]

maf sensor will help if its never been cleaned.it will read the airflow better without the soot on it.i had this same problem and it ended up actually being bad spark plugs.under idle to 2000 rpm it would run alright,but wouldnt run any higher without cutting out and starting to studder.easy check,just pull one and see what it looks like.type of plug also will make a difference.i wont run champion plugs anymore unless its my lawnmower.autolight plugs always seem to work better than most others i have used.

 

[sweetk30]

wow a dubble poster.


go check your other thread. i put up lots of info there .

and for those who are looking its in the ifs section.

 

[noJeepshere]

wow a dubble poster.


go check your other thread. i put up lots of info there .

and for those who are looking its in the ifs section.

Figured I'd cover more ground with two posts.

Thanks for the info, cleaning the MAF really seemed to help it alot, but there is still a bit of a stumble under heavy throttle. I think maybe the fuel pump is wearing out (it is the original at 130k) and is ready to give out.