Stumbles on cold start and low fuel pressure?

JS69862000

MEMBER
2006 CHEVROLET SILVERADO
4.8L
V8
2WD
AUTOMATIC
200,000 MILES

When cold vehicle stumbles at start and then idles normal, also when idling has a small miss. No codes at all or showing. Checked fuel pressure when vehicle is off 50 PSI some loss of power when truck is under load.

Tuesday, September 27th, 2022 AT 8:01 AM

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
43,072 POSTS

The fuel pressure sounds okay, I would say the MAF sensor needs to be replaced which is common on these trucks with many miles. also, I would clean the throttle bore, here is a generic guide on how to replace the sensor and instructions below to show you how on your truck. I have included a video on how to service the throttle bore.

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

and

https://youtu.be/Z3LDHdS1upo

Check out the images (below). Please let us know what happens.

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Tuesday, September 27th, 2022 AT 11:24 AM

JS69862000

MEMBER
5 POSTS

Okay, replaced MAF and cleaned throttle bore, no change. Checked the fuel pressure again at the rail no getting 42 PSI. Still thinking maybe, a weak fuel pump. Any thoughts?

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Wednesday, September 28th, 2022 AT 2:13 PM

KEN L

MASTER CERTIFIED MECHANIC
43,072 POSTS

Yep, the fuel pressure is low.

Fuel Pressure (Key ON, Engine OFF). 385-425 kPa (55-62 psi)

I would install an AC Delco fuel pump here are the instructions on how to do the job in the images below. Check out the images (below). Please let us know what happens.

Images (Click to make bigger)