2006 Chev 2500, after it sits for a day when you start it you have to hold the key longer than normal , when it starts it runs rough for a few seconds and then runs good. I know it's a fuel issue but is there a check valve that could leak back to the tank?

 

Yes there is a check valve in the fuel pump assembly. You can replace the fuel pump or add a check valve in the fuel line near the tank.

 

put a fuel pressure tester on it and see where its at and if it does bleed down after sitting

 

thanks for the help