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Hard to start when weather is warm

Tiny
JEFFREY SWEENEY
  • MEMBER
  • 2000 GMC SIERRA
  • 5.3L
  • V8
  • 4WD
  • 248,000 MILES
Was getting all 4 o2 codes, replace all 4, cleared light now getting o2 codes on both banks, makes truck hard 2 start when it's warm outside. First time starts good after that it fills like it's loading up while idling and hard 2 start, when light is on.

Truck listed above is a 1500.
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Friday, April 30th, 2021 AT 12:04 AM

1 Reply

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

I doubt the issue is or was the sensors. Hard to start could be from fuel pressure and the engine running lean. The sensors will pick that up and set a code for lean running.

https://www.2carpros.com/articles/engine-cranks-excessively-before-starting

What were the codes?

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I would start with a fuel pressure test.

Key On Engine Off 55 - 62 psi

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

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

Good possibility the fuel pump is the failure.

Roy

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Friday, April 30th, 2021 AT 2:41 AM

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