Code PO171, fuel pressure drops when revved

2005 CHEVROLET CAVALIER
183,000 MILES • 2.2L • 4 CYL • 2WD • MANUAL
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MIKE KEREZMAN
  • MEMBER
  • 2 POSTS
Car will fall on its face accelerating only after full warmed up, never cold. I hooked up a
fuel pressure gauge to the fuel rail. It read 49 PSI with key in run position. It also
read 49 PSI engine idling. However, when i revved the engine to 2,000 to 3,000
RPMs the fuel pressure dropped to 20 PSI. Pulled the vacuum line from fuel
pressure regulator and no gas dripped out but no improvement in fuel pressure
either when idling. I need a fuel pump.
May 7, 2021 at 1:24 AM
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ASEMASTER6371
  • ✓ASE Certified Mechanic
  • 52,796 POSTS
  • ASE Certified Mechanic
Good morning,

This sounds like the pump is failing under load.

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

The spec is below. Even with the key on, engine off, the pressure is too low. I would suggest replacing the fuel pump.

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

Roy
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May 12, 2021 at 2:00 PM
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