engine misfire why?

2003 GMC ENVOY
142,000 MILES
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BECCAPARR13
  • MEMBER
  • 1 POST
We ran out of gas.. After getting gas in it the check engine light turned on and goes from constant to flashing on and off. Idle shaking pretty good. Took to O'Riley's and the codes that showed up were P0300, Co291, Co235 and Co237. Changed out all 6 spark plugs and fuel filter. Problem remains. Does not want to get up to speed and smells of gasoline after starting.
Aug 17, 2019 at 7:26 AM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,240 POSTS
Welcome to 2CarPros.

The flashing engine light is caused by a misfire. The P0300 indicates there is a random misfire. The other two codes deal with a wheel speed sensor on the rear.

I understand you replaced the plugs. Have you checked fuel pressure to confirm it is within the manufacturer's specs? I'm questioning if the pump or regulator has been damaged by running out of fuel. That is where I would start.

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

Here are the specs for pressure:

FUEL PUMP PRESSURE
Fuel Pressure .................... 334 - 375 kPa (48 - 54 PSI)

Fuel Pressure Drop (After 1 minute) .................... 34 kPa (5 PSI)

Check this and let me know what you find.

Take care,
Joe

May 17, 2021 at 10:35 AM
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