Car stalls often when I step on gas

Tiny
ROYCAR71
  • 1998 GMC JIMMY
  • 6 CYL
  • AUTOMATIC
  • 125,708 MILES

My car stalls often when I step on gas. At takes about 3 or 4 cranks to start. Is this a sign that my fuel pump is gone? Thanks.

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Friday, July 20th, 2012 AT 6:57 PM

23 Replies

Tiny
HMAC300
  • EXPERT
  • 49,800 POSTS

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.

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Friday, July 20th, 2012 AT 7:06 PM
Tiny
ROYCAR71
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I am a little vague on somethings. The throttle plate is located in the air filter assembly right? Where would iac hole? Thanks.

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Saturday, July 21st, 2012 AT 12:44 AM
Tiny
HMAC300
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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.

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Saturday, July 21st, 2012 AT 3:24 PM
Tiny
ROYCAR71
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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?

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Monday, July 23rd, 2012 AT 12:30 AM
Tiny
HMAC300
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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.

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Monday, July 23rd, 2012 AT 2:30 PM
Tiny
ROYCAR71
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Yep, I just order a fuel injector pressure gauge to test my psi on fuel test port. I will post results.

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Monday, July 23rd, 2012 AT 7:15 PM
Tiny
HMAC300
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Most auot parts stores have them for rent where it won't cost you anything if you birng it back from a deposit.

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Monday, July 23rd, 2012 AT 7:18 PM
Tiny
ROYCAR71
  • MEMBER

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.

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Thursday, July 26th, 2012 AT 10:45 AM
Tiny
HMAC300
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That can also be the fuel pressure regulator bad.

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Thursday, July 26th, 2012 AT 3:57 PM
Tiny
ROYCAR71
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Could I test the fuel regulator or just replace it. Is it easy to replace?

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Thursday, July 26th, 2012 AT 5:23 PM
Tiny
ROYCAR71
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Forgot to include, wouldn't check engine light come on if it was fuel pressure regulator?

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Thursday, July 26th, 2012 AT 5:31 PM
Tiny
HMAC300
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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.

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Thursday, July 26th, 2012 AT 5:33 PM
Tiny
ROYCAR71
  • MEMBER

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.

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Sunday, August 5th, 2012 AT 9:02 AM
Tiny
HMAC300
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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.

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Sunday, August 5th, 2012 AT 8:59 PM
Tiny
ROYCAR71
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Doing these check means I have to take fuel pump out right? If so, I should replace pump anyways, right?

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Sunday, August 5th, 2012 AT 9:20 PM
Tiny
ROYCAR71
  • MEMBER

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.

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Sunday, August 5th, 2012 AT 9:57 PM
Tiny
HMAC300
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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.

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Sunday, August 5th, 2012 AT 11:24 PM
Tiny
ROYCAR71
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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.

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Monday, August 6th, 2012 AT 12:25 AM
Tiny
HMAC300
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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.

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Monday, August 6th, 2012 AT 1:21 PM
Tiny
ROYCAR71
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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"?

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Tuesday, August 14th, 2012 AT 10:09 AM

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