2009 Sierra 1500 stumbles on start up. Possible fuel pump?

[dtspitcherguy]

I have a 2009 Sierra 1500 5.3L with about 125000 miles on it. I use and change synthetic oil regularly, use Marathon Gas unless I have Kroger Fuel Points, and have had no major troubles since owning it.

 

Recently,about once a week it will stumble on start up. Once it stumbles it starts fine and runs great. My mileage is consistent and no other issues in driveability. I initially thought I was not turning the key completely, but that is not it. I had the battery, starter and alternator checked at Advanced Auto and everything checked out fine. Put a bottle of Seafoam in to try and clean injectors/etc. Then about a day or two later my check engine light came on. Went back to Advance and it threw a P0442 code for a small EVAP leak. Reset the gas cap, cleared the code and it has not come back on since. However, once a week or so, it will still stumble, catch and run fine.

 

Looking for some advice. In doing some initial research, it seems like the fuel pump/filter assembly is probably to blame, but also concerned the EVAP system may be to blame. Thanks for the help!

[BlackZ71Silverado]

Is your truck stock or do you have an aftermarket "cold air intake" installed?

[dtspitcherguy]

No, completely stock other than a small sound system.

[gmtech4]

i wouldnt be guessing the pump just yet sir ,,,,,alittle more diagnoses is required im afraid

[Snow White]

this was the first sign i had a throttle position sensor TPS ON THE WAY OUT. you can check the voltage but i'm not sure what it's suppose to be. it'll get worse pretty quick, fail into 4 cylinder mode all the time and the dash will go christmas tree if that is the problem.

[royboy09]

My truck was doing the same thing.

The check engine light I was getting had to do with the purge valve.

Everytime I stopped for gas my truck acted up when I'd start it up.

Kinda like the starter was sticking.

I replaced the purge valve, about $15 bucks at Autozone.

Purge valve located on right side of the intake.

Fixed her right up. Find out what code your truck is throwing.

Mine was PO496.