Rought idle on start up

Tiny
ASABASS
  • MEMBER
  • 1993 CHEVROLET 1500
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 265,000 MILES
If my truck sits for longer than a few hours, it will idle very rough on start up. If I shift it out of park during this time it will stall and shut off. After a few minutes of running rough it evens out and there are no issues until it sits for a few hours again.
Friday, June 3rd, 2022 AT 12:40 AM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
I have seen where one of the fuel injectors is leaking causing the engine to flood out. To be sure please remove the air cleaner then start the engine and shut it off. When you shut the engine off use a flashlight to look at both injectors to see if you can delete any leakage. If so, that fuel injector will need to be replaced. Here are instructions on how to do the job. I would check Rockauto for the parts. Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.
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Friday, June 3rd, 2022 AT 5:29 PM
Tiny
ASABASS
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  • 2 POSTS
The video is after letting it sit all night. Would outside temperature affect the injectors? We have had a few days over one hundred degrees and it seems to no chug as much then.
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Sunday, June 19th, 2022 AT 10:49 AM
Tiny
KEN L
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  • 54,137 POSTS
Yes, I have seen where the gasket under the throttle body blows out causing a vacuum leak. Check out this guide to help confirm the issue. Spray the engine cold, toward the rear of the throttle body. If the idle picks up the gasket is no good.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please run down this guide and report back.
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Monday, June 20th, 2022 AT 1:26 PM

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