When accelerating to pass the motor stumbles or hesitates and almost shuts off?

Tiny
2XTROUBLE
  • MEMBER
  • 1990 GMC TRUCK
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 263,200 MILES
Recently I got my truck listed above running again after sitting for a while and after replacing all the fuel components in the tank. The truck was running great then all of a sudden when you go to step on gas to pass motor stumbles or hesitates and almost shuts off. However, if you ease into the gas, it runs fine. I have replaced vacuum lines on throttle body, and MAP sensor. Any suggestions? Thanks for any help.
Thursday, January 19th, 2023 AT 5:22 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,477 POSTS
Hi,

Your description sounds like it either has low fuel pressure or there is something restricting the pressure.

I realize you replaced nearly everything, but I would suggest checking pressure so we can eliminate that as a possible issue. It could be low for various reasons. On the other hand, it could be high due to a failing fuel pressure regulator.

Here is a link that explains in general how to test pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Also, if you haven't already, check to see if there are any diagnostic trouble codes stored in the computer. The truck has an OBD1 system that doesn't require a scan tool to retrieve codes. All you will need is a short jumper wire or even a paper clip.

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Let me know what you find or if you have other questions.

Take care,

Joe
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Thursday, January 19th, 2023 AT 7:52 PM
Tiny
2XTROUBLE
  • MEMBER
  • 1 POST
Thank you for the answer. I plan on replacing the left injector and the two injector connectors this week to see if that will help.

Regards,
Charles Troublefield
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Friday, January 20th, 2023 AT 8:51 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,477 POSTS
Hi,

You are very welcome and thanks for the update. If possible, let me know if that takes care of the issue for you. I'm interested in knowing.

Take care,

Joe
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Friday, January 20th, 2023 AT 8:35 PM

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