Stalling at low acceleration and shutting off in reverse at low acceleration

Tiny
COLLIN LACOBELLI
  • MEMBER
  • 1990 GMC SIERRA
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 232,000 MILES
I recently bought the truck above and noticed a problem when I test drove it. At idle the truck runs beautiful and when you put it in drive or reverse it’s fine but at low acceleration in drive it will stutter and sound like it’s going to shut off but won’t and it drives fine going down the road or at WOT. When you put it in reverse and accelerate slowly it sounds the same as drive but it will stall out and shut off unless you floor it in reverse.
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Thursday, January 9th, 2020 AT 5:08 PM

3 Replies

Tiny
ASEMASTER6371
  • EXPERT
Good evening,

I would start by checking the EGR valve on the intake manifold by the throttle body. Remove the hose and see if it still stutters. If it does not, then the valve is bad causing a vacuum leak off idle.

https://www.2carpros.com/articles/stall-at-idle

I would also check the fuel pressure. Low fuel pressure will cause this as well.

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

Lastly, check the ignition timing. Follow the procedure I attached and set it at 12 degrees before top dead center.

Roy
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Thursday, January 9th, 2020 AT 5:32 PM
Tiny
COLLIN LACOBELLI
  • MEMBER
I disconnected the EGR valve and the problem went away in both drive and reverse. Thanks for the help.
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Friday, January 10th, 2020 AT 6:01 PM
Tiny
ASEMASTER6371
  • EXPERT
You are welcome.

Always glad to help.

Roy
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Friday, January 10th, 2020 AT 6:28 PM

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