Starts right up when cold. ONce it is hot sputters, spurts, stops, no start

Thank you. I will have to try that I am afraid.

before you jump right on the fuel pump, I recommend that you test your fuel pressure first. if you don't have a fuel pressure gauge tester, you can rent one at an Auto Zone or Advance Auto. They're not that expensive to buy and saves a lot of money in case its not the fuel pump. Diagnostics on each possible cause is recommended before any repair of this nature is performed. It hooks up to the schrader valve on the fuel rail located above your injectors and should have a plastic cap screwed on similar to your A/C schrader. Pressure should be between 35 and up to 40 lbs. The GM pumps usually good for 80,000 to 100,000 miles. If you have put that kind of miles on then, its a good start to diagnosing your problem. CHECK YOUR TIMING CHAIN before doing anything! Rotate your crank pulley with a socket, don't push or pull with pressure, you are checking for Free Play only. If the crank pulley moves back and forth easy then your timing chain is worn out and jumped teeth on gear sprocket. Good luck. Kool Tool

Hello. Thank you very much, all of you. It was the fuel pump. Changed it today and problem solved. I did put the gauge on first though to check the pressure. Was 20, even when running. Again, thank you all.

Oh really? Running at 20 psi fuel pressure? Wow. Also you said the check engine light was not on so how did you get code P1780 that you ask about in your next question? One more thing, did this pump have a pulsator on it? Just wondering about this whole deal.

Hello. The check engine light comes on but it did not come on when it would not start. It does work, but for the problem about the not starting or running rough had no engine check light for it. The pump pressure being 20 and a bit does not necessarily mean it was at that all the time. It does mean that when hot, the gas pressure from the heat of the engine would be pushing back pressure {vapoured perhaps} and the pump just did not supply. It does run now much more responsively. Pump now at 45 or so. Thanks again. Ken