Car stalls often when I step on gas

scan for codes an dcheck fuel pressure first. clean throttle plate with choke cleaner on both sides. as well as iac hole if it has one. fuel pressure shold be 60-66 psi. if below that it may be a pumpor filter clogged.

I am a little vague on somethings. The throttle plate is located in the air filter assembly right? Where would iac hole? Thanks.

go to tune up on the site here it will show you where the throttle plate is. but it is just above the intake manifold. the iac hole is a an oblong hole ontp if you have one.

Ok, found it already and took it off top of intake manifold. real easy to get to. I cleaned plate, inside throttle body by moving spring mechanism back in forth and got alot tar gummy stuff off. I used throttle body cleaner from auto zone. Put everything back together. I drove to take someone home and did not have any problems. gmc jimmy ran smooth even though i noticed gas pedal went down easy and there felt like a lose of power, but ran fine nonetheless. Today, being sunday I got up early and change my fuel filter and gassed up. There was few times I had to crank truck more than once to start and stalled/sput when I stepped on gas for a few secs and then it would go hard. I thinking to just go ahead buy fuel pump and replace it. If it was a relay. Wouldn't check engine light come on and fuel pump will not work, thus car would not start, right?

actually with a fuel pum check engine light will not come on unless it sets a code of a lean condition. so make sure you check fuel pressure first before you change it, it may all be for naught.

Yep, I just order a fuel injector pressure gauge to test my psi on fuel test port. I will post results.

most auot parts stores have them for rent where it won't cost you anything if you birng it back from a deposit.

Yes, I know. Over here I get round around alot so I order one and got today. I hook it with know problems. I got 60 psi with engine running and when i turned off engine it went to 0. I saw some videos that said "your bleed down should not go to low". If so, maybe I am missing a o-ring when I change the fuel filter or something. Plus recently, when starting up it takes a few extra cranks to start and when you step on gas it feel like it is stalling and there appears to be knock sound coming from rear underneath car. Then it take off fast.Thanks.

that can also be the fuel pressure regulator bad.

Could I test the fuel regulator or just replace it. Is it easy to replace?

Forgot to include, wouldn't check engine light come on if it was fuel pressure regulator?

you have to replace it, if there is avacuum line going to it then disconect it and pressure should rise by a few pounds of pressure
its all part of the fuel metering system though and that runs around $00 i think, check with an auto parts store.

I replace fuel pressure regulator. When turn engine on afterwards it backfired from engine area. I did use throttle body cleaner on "Idie air senser" and around intake manifold. When drove to fill up , it rode smoothly. but once after fill up, than startup. It backfired a little bit. Than took off. I checked pressure with engine on and cranked up. the psi was at 55 to 50 and it would not hold. I check again after returning from gas station same thing. I did feel instance where they felt like lost of power when step on gas. I have "CSFI" system so it was not easy as you stated in your early replies. but I changed out old fuel pressure with new one. What would be, next course of action.

fuel pressure must be 60-66 psi on your system with engine idling.Check for the following conditions:
? Low fuel pump voltage due to high resistance connections.
? High fuel pump voltage due to internal pump binding.
? Poor fuel pump ground.
? Partially restricted fuel pump strainer.
? Incorrect or faulty fuel pump.

if this still doens't fix it then take to a pro as it may be an injector problem and it will be cheaper for him to check it out than for you to do it.

Doing these check means I have to take fuel pump out right? if so, I should replace pump anyways, right?

I forgot to include some pictures. These have iac cleaned, fuel injector spider; which now GMC recommends updating to "MFI" system. Fuel pressure regulator old and new.

do what it says to do to test first before replacing fuel pump. But your pump pressure should be the spec that i gave you in the previous answer. make sure to get the correct pump if you do change it, but it kinda looks like the pump is bad or going bad. Make sure the voltage is good though as well.

I can hear pump kinda loud when I turn on engine too. I will take my chances on replacing it since I don't want it to go out on me and I am not so fimilar with testing it (except pressure which is lower than what you said). I am looking at after market pumps now since they are way cheaper than OEM. Once out of fuel tank, can I use same connector or do I have to splice wires and replace with new connector? also, once installed and not attached car. can I turn engine to on position to see if new pump is operation before installing all the way on, that way I don't have to do this job again? Thanks.

you should be able to use the same conector and the pump needs fuel to lube it so dont' turn it on without fuel in tank or being in tank.

I ordered pump and will be getting this week. I forgot to ask "is it safe to drain a portion of my fuel through strata valve on fuel line with fuel pressure gauge by pressing pressure relief button with see through bleeder hose into gas jug"?

i don't know why you would do that, just disconnect the fuel filter and put a rubber hose on it and go into a jug. it won't build up any big pressure as long as it is working.

Well I change fuel pump and went under intake manifold put in new plenum gasket to see it that would make different. It took me 1 day and have. Due to bad whether and first time doing. I notice that there where 2 bolts under intake manifold that would not get tight and seem striped. It still does same thing at start up. It spits and sputters than it take off smoothly. This happens most when i start up it up. It does start up now with out so much cranking. Maybe fuel pump needed changing too screen was pitch black and appeared to be clogged. I did not clean out tank even though it had some dark in it.

Correction, actually when i step on gas after start up it spits and sputters/backfires from engine area. with a few soft revs I then take off smoothlty.