2008 Silverado
37,000 miles out of warranty
5.3 Flex fuel Run regular or 10% ethanol

Hard starting in the morning
Seems to be worse in the morning after not running for 6-10 hours.
It turns over 1.5-2.0 times more then normal before firing up. It then almost dies then revs up to 1200rmp then almost dies then revs up to 1200rpm then runs normal.

After the start up it runs and drives normal. Shut it off for a few hours it does it agian but not as bad. Let it sit over night worse again.

No check engine lights ect.

Little background, last week I drove home 350 miles. Drove it hard. Loaded with an ATV and full of stuff 80-90MPH. When I got to town I was out of gas. I put 25.5 gallons in. Means I had 0.5 to 1.0 gallon in the tank. I filled up with cheapest gas in town to save a dollar. Put in 10% ethanol. No issues until the next morning. Since filling I have put 26 miles on.

Tried to change the fuel filter thinking I sucked something in running it empty, well no filter on the pickup DUMB!

What do I check next? I plan to put seafoam in the tank tonight. Thoughts?

 

Did you ever find a solution to your problem? I have almost the exact same issue

 

Sounds like the check valve in the fuel pump assembly is bad. It lets the fuel bleed back into the tank when not running. You can do the right thing and change the fuel pump or add a check valve in the fuel line. It worked for me.

 

THIS x 10!!!

 

cycle the key to run for 2 seconds and repeat multiple times...then try to start it. it will prime the fuel system. if it starts normally, its the check valve.

 

And if it still doesn't start.. not the check valve .then the?...
and now I'm not hearing the fuel pump. Wth? I changed the fuel pump twice already