1997 Tahoe power problems

[poonjahb]

I have a 1997 Tahoe 4x4 with the 5.7l Vortec with about 93,000 miles on it.

I have been having some problems with it lately, and it doesn't seem to have anywhere near the power of other trucks and SUVs from the same timeframe that I have driven.

If the engine sits for 15-20 minutes, it starts right up but if I try to take off without letting it run for a few minutes it will bog down and backfire on me for the first few minutes of driving. I have read some of the threads about the Fuel Pressure Regulator and have a feeling that will need to be replaced from reading the descriptions here.

Also, it doesn'e accellerate exceptionally well, bogging down for a second or two right when I hit the gas then going fine until it gets to about 3500 RPM, where it will sputter and slowly climb until it shifts. When accellerating from a stop it will again bog down and sputter a bit if I hit the gas hard for a few seconds, really makes me nervous pulling out into traffic from a stop sign.

Any help on this would be greatly appreciated, could the fuel pressure regulator be doing all of this? I replaced the fuel pump last year after it completely died on me and left me stranded in a parking lot. Plugs, wires, distributor cap, rotor, EGR valve, intake, free flowing exhasut have all been done within the last year as well.

[2000CAYukon]

When the fuel pressure regulator goes bad extra fuel is sucked in thru the vacuum line. So yes this can be your problem. The bad news is that the top half of the intake has to come off to replace it.

Did you you check the timing? A scan tool is required to set the timing on the Vortec engines.

//2000CAYukon

[poonjahb]

Have not checked the timing yet, I've got a cable and some software for my laptop and as far as I can tell everything looks good. Guess I should probably take it somewhere to check the timing as I don't really know what to look for.

If I have to take off the top half of the intake, what gaskets and such will need to be replaced?

[montecarlogmc]

Originally Posted by poonjahb

Have not checked the timing yet, I've got a cable and some software for my laptop and as far as I can tell everything looks good. Guess I should probably take it somewhere to check the timing as I don't really know what to look for.

If I have to take off the top half of the intake, what gaskets and such will need to be replaced?

Have you changed fuel filter

[poonjahb]

Yes, fuel filter has been replaced. Also replaced all of the O2 sensors. I think there is some other stuff, but can't think of it off the top of my head.

I've had one friend tell me that it may be a bad fuel injector, but hope it is something like the pressure regulator as the cheapest I can find the injector kit is around $450.

[poonjahb]

Got it figured out. Everything runs great now. Turns out the mass airflow sensor was bad and was causing it to run lean, replaced it and it runs like a champ now.

[obadran]

I read your orignal post, and what you are describing exactly matches the problem I'm having on my 96 yukon.

How did you figure out that you MAF sensor was bad? I wondering if that is the same problem for me but I'm a little hesitant to drop $200 some dollars for a "let's see what happens".

I'm not getting any fault codes for the MAF sensor and the truck seems to no differently with the MAF connected or disconnected.

Thanks.

[poonjahb]

I actually had the dealer looking at it, but they told me when they unplugged the MAF it started running great. Has been running good ever since with the new MAF.