Hello I have a 2001 chevy 2500 HD with 6.0 gas engine. I have replace all of the O2 sensors, new fuel pump, all new injects , new wires and plugs , new brakes and master cylinder and lines , and just change the engine oil and filter. This truck has been sitting for about 10 years .

the problem is some times you start it up it runs fine until it get warm then I tach up to about 2000 rpm’s .and sometimes it tach up to 2000 rpm’s when it’s cold start.

I ran a smoke test but I can find any vacuum leaks . Because I thought it acts like a vacuum leak ..

And its shows no dc codes.

any help would be greatly appreciated

thanks kybp

 

Check the fuel pressure regulator. Pull the vacuum line off and see if gas runs out of either the vacuum line or the fuel pressure regulator's nipple.

 

After ten years, all the gasoline is worthless unless it was treated with gas storage liquid. If rodents didn't get in there to chew away at your wires, you are lucky. You need to add some Techron or Sea foam, fill it up and take this pickup out for a good long drive, at high RPM's. It’s called the “Italian Tuneup”. Find a good county road and floor the gas pedal until you can see all the carbon going out of the exhaust pipe.