I have 2002 blazer hard to start.If you bump the key it tries several times then it will start.Once you get it started it does good at idle but stomp the accelerator it will stumble backfire.Just had it tuned up (was doing this before the tune up) had it hooked up on Diagnostic deal with no codes coming up.

 

You need t do a fuel leakdown test. A fuel delivery problem will not throw any codes. If you don't have it, get a loaner fuel leak test gauge. Hooks up on the schrader valve just before the fuel line go into the plenum. Key ON engine OFF, in the first two seconds that the fuel pump is running you must have 60-66psi. Then must remain above 55psi for ten minutes. Post your results so the forum can help you from there. Very common problem on Blazers.

 

Ok thanks.I will give it a try this week.