Wont start on first try.
 

I have a 2000 2500 silverado with a 6.0. Truck will no longer start on first crank, usually starts on second try sometimes a third try is necessary. There is real bad bad gas smell when it does start. Sometimes it runs rough for 3 or 4 seconds after it starts. Any thoughts would be greatly appreciated! Fuel filter is fresh, manifold gasket replaced 8 months ago, regulator as well. No codes showing.

Something similar happend to my 99 Silverado. Wouldnt crank on first time, could hear fuel pump click on, smell of gas and bad gas mileage. Turned out I needed to replace my fuel pump and fuel filter. To make sure it is the fuel pump try this (if stock chevy pump).

1. Turn the key to slot right before ignition.
2. If you hear a click in your gas tank, good. (means pump isnt dead)
3. Now turn truck on. If you hear a winding high pitch sound that means your fuel pump is going out and needs to be replaced.

Hopefully this helps you. I took mine to a shop and pump/filter together costs around $800. You could do it yourself for around $400.

Good luck,
Marcus

turn the ignition on and off about 5 times slowly and then try to start. if it starts right away a leaking check valve in the system is allowing the fuel system to loose prime