2011 traverse

have a 2011 traverse customer complaint is long crank time after fill up two codes p0451 and p2187 no intake leaks and ftp sensor operating normal checked evap system found system working normal checked purge now I feel it might be working normal after doing test fuel trims showing 0 and 7 on long term raise rpms and find long term drops some what then comes back leaning towards purge valve sucking fumes any ideas would be great car is currently on e cleared codes and no codes come back haven't filled tank to try to duplicate

Disconnect vacuum line from purge and see of it hold vacuum

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If you don't have access to a vacuum pump you can try to blow through it, but that's not as accurate as vacuum test

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You can use your scan tool to test the purge valve. Go to functional test and find evap purge / seal. Set your custom data list up to show fuel tank pressure , purge valve % and evap vent solenoid valve. now command your purge valve to 0% and seal the system and monitor your fuel tank pressure. it should slowly increase. If it decreases then your purge valve is leaking. The vacuum pump method is more accurate but this method has worked for me on more than one occasion, even with slightly leaky valves. I`v attached a jpeg image of a 2017 camaro that had a slightly leaking purge valve.

Worked on a Subaru Outback I think it was a few years ago. Same symptom and once it did start you had to keep rpms up with right foot while basically using left foot on brake to control the forward motion. You would have to do this for a half mile or so and then it would drive like normal. Ended up being purge valve being stuck open flooding the engine with vapors during fill up.

Totally agree with everyone else, purge valve is definitely suspect. I found one on another 3.6L just this week. :lol:

You can also try cycling the purge valve wide open and closed repeatedly, to see if you can get it to stick open.