After getting gas the last few times my 2019 Sierra has a hard time starting and runs rough for a few minutes when it finally does start.
So far I have changed the vapor canister vent valve on the motor and the vapor canister solenoid underneath the truck with GM parts.
Neither has worked to fix the problem. Any ideas?

Not sure if you are familiar with how carb engines started you would give it a bit of fuel. When starting yours does giving it a bit of gas on start help?
Do you have a bidirectional scan tool to control the purge and vent valve?
With the scanner you can see the pressures on the fuel or if it is logging the issue just not throwing a light yet.

 

Hello and thanks for your reply. I am familiar with how carb engines work. This truck is a 2019 fuel injected vehicle which shouldn't require any input from the driver to start. However I have tried to depress the accelerator pedal from slightly to wide open when this event happens at the gas pump, much to no avail. fumbles stumbles and takes several attempts to start. Yesterday after refueling it literally turned over so long I thought my battery would be dead!

 

Will need to see if the EVAP Purge solenoid is leaking.
And need to see what the fuel pressure is doing.

 

So other than fueling up, the engine starts and runs OK?
Are you topping off when you fill up?

 

It sounds like your battery is dying. Is it the original battery? If its the original battery, just replace it. Situations where you were driving for a while, then turned off for few minutes, then try starting again and it cranks long time or slowly, these are signs of battery dying.

Don't go crazy chasing the fuel system stuff, you're wasting time/money. The mention of if you "top-up" eludes to the evap/purge solenoid getting blocked when that is the case, DO NOT TOP UP when your gas pump handle clicks off, thats it, dont squeeze it again, you're not doing your fuel system any favors, and you're actually causing things to go bad sooner.

Resist the urge to pump more gas in, its not gonna make any difference that extra bit of gas, you'll burn that just idling at a stop light, just let the pump stop itself, pull it out and hang it up.

 

Just don't eat so many damn BEANS, and maybe your "gas problem" will go away.....Just send me the $20 for this advise, and take a slug o' good ole' Pepto Bismo....OR a large chunk o' EX-LAX

 

Hahahahaha