Evaporate system leak test failed

Tiny
XJSHEN
  • MEMBER
  • 2003 PONTIAC MONTANA
  • 3.4L
  • V6
  • 2WD
  • AUTOMATIC
  • 85,000 MILES
Evaporate system leak test failed by code reader. While Got code p0172, and service engine soon light. Repair shop repaired p0300, but created p0172. What is possible reason from fix p0300 and that cause p0172?
The reason for p0300 was throttle body gasket was leaking, and now it was fixed, and no misfiring.
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Saturday, November 21st, 2020 AT 2:39 PM

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Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The idea that you had a P0300 first could have caused the Po172 to set. That code indicates a rich fuel mixture. Basically, the engine is getting more fuel than it needs.

Since you had a misfire, that could have allowed unburned fuel to enter the exhaust and set this code. What I would do is this. Reset the computer (delete the code) and see if it comes back. If it does, then I would recommend checking to see if there is an issue with fuel pressure. There is a vacuum hose that attaches to the fuel pressure regulator they may have left disconnected. See pic 1 I circled where the vacuum hose will be connected.

The regulator is located on the fuel rail on the top of the engine. Check to make sure that hose is connected. If it is, disconnect it and make sure there is no fuel in it which would indicate the regulator is bad.

If you want to check fuel pressure, here is a link that shows in general how it is done. However, I would try what I suggest first.

__________________________________

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

tHE ATT
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Saturday, November 21st, 2020 AT 8:17 PM

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