2005 GMC 1500hd hard start problem.
 

Hi I have a 2005 GMC 1500HD with a 6.0 vortec and it seams to take a few time to get it running after it sits over nite. When I turn the key on to prime the fuel pump it makes it start better . I added a new coolant temp sensor and some extra ground wire and a new battery . The truck has 300000km is there any thing I should look at ? After I get it running it works good all day . I been looking at the fuel Schrader valve test port to check for leaks there . Have any body changed them on these trucks ?

Re: 2005 GMC 1500hd hard start problem.
 

the check valve is going out and fuel pressure is probably dieing off overnight.

You can cycle the key on and off a few times before starting it or change the pump assembly in the tank.

Re: 2005 GMC 1500hd hard start problem.
 

Or you have an injector/fuel pressure regulatorleaking down overnight

When the truck starts, how does it run? Smooth right away, or rough for a few seconds?

Re: 2005 GMC 1500hd hard start problem.
 

I think that is my problem. I need to get a pressure gauge on the fuel rail.I did replace the pump a few years ago . turning the key on and off is helping right now . I got bad gas this winter then my problem started .