Fuel system or transmission?

Tiny
RPOLITTE
  • MEMBER
  • 2014 GMC ACADIA
  • 3.6L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 125,500 MILES
So it started with the occasional kick as I call it very intermittent nothing consistent, but now my car is struggling to climb every hill it is not downshifting and it’s cutting out or shuddering, no warning lights on dash transmission fluid is full and doesn’t look dark, had an oil change recently it’s losing power and shifting funny I had a foul smell coming from it the other day and there’s a hesitation with it starting it start just has to be cranked over longer
Monday, July 28th, 2025 AT 4:23 PM

5 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,138 POSTS
This sounds like a weak fuel pump (low or high pressure) or the engine is misfiring, I would make sure the tune up is up to date, spark plugs and coils. Also, service the throttle body. Here is a guide to help check the fuel pressure. You might have a tank of bad gas as well. Also, even thought the check engine light is not on I would run the codes

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Do you know the long and short fuel trims? That can help tell us what is going on as well. You can find them from the scanner.

Spark plugs - ACDelco 41-109

I have seen the high pressure fuel pump go out on this car, Check out the images (below). Let us know what you find.
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Tuesday, July 29th, 2025 AT 11:16 AM
Tiny
RPOLITTE
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  • 3 POSTS
I ran codes and nothing and I was told there is no actual fuel filter that it is part of the fuel pump assembly and do not know about fuel trims
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Tuesday, July 29th, 2025 AT 3:05 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,138 POSTS
Yep, there is no fuel filter, just a strainer at the fuel pump. The trims are read on the scanner and will help tell us if the system is lean which will point to the HPFP or the lift pump.
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Wednesday, July 30th, 2025 AT 9:14 AM
Tiny
RPOLITTE
  • MEMBER
  • 3 POSTS
So reran scanner it’s in my evap system I’m thinking purge valve purge canister but does that explain the kick and issue with downshift?
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Wednesday, July 30th, 2025 AT 3:25 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,138 POSTS
If it is stuck open than yes you could have a leak, here is the location of the valve, once removed you should not be able to blow through it. Check out the images (below). Let us know what you find.
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Wednesday, July 30th, 2025 AT 5:28 PM

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