Power loss and surge and RPM loss and pick up

Tiny
JAMES PLOWER
  • MEMBER
  • 2000 MERCURY COUGAR
  • 2.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 93,000 MILES
After driving car a while in high heat with A/C on, car will lose rpm's and feel like it's going to stall. Then when you apply gas it will then catch, rpm's will rise and then power will come back after a second or so then rpm's will drop again and no power and then all of the sudden the power and rpm's will return. Surging feeling while this is happening and rough idle. Once car cools off no problems again. Seems to be heat related when outside temperatures get above 89 to 90 degrees. And while running A/C car didn't stall out, but felt like it was about to. Didn't matter if on level ground or going up hill or down hill. Car has over half tank of fuel.
Thursday, July 2nd, 2020 AT 3:23 PM

1 Reply

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Based on all this info, I am going to think that the purge valve is sticking open when it should be closed. Basically this is a normally closed valve that when opened it allows fuel tank vapor into the engine. This is so that vapor is not omitted to the atmosphere and it will reduce emissions from the engine. If this is stuck open it will allow too much fuel in the engine and it will actually causing the engine to bog down and possibly stall.

I attached the info on this system. Please review this and let me know if you have questions.
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Thursday, July 2nd, 2020 AT 5:37 PM

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