03 Impala 3.8 eng. Ran fine shut it off tried to start about 1/2 hr no start. Let sit another 10 mn started. Drove home fine. Next morning no start let sit 10 min started, While trying to no hum from pump, after starting and shut off fuel at fuel rail. Changed pump started fine drove fine. Shut off let sit for 1 hour no start no hum from pump. Changed fuel pump relay. and all the same problems continue. Any ideas before she goes to the shop. Also, will the $100-150 scanner find a problem like this Thanks for any help out there.

 

I have a related issue with my 1999 Chevy Tahoe LT 5.7L V8. Always started fine, no hesitation just fired right up. Took it for a tune up, and all of a sudden she won't fire up. Put a new battery on and still will not crank, yet after 10 minutes it will. Took it back to the shop and they claimed the key is worn and tripping the security system causing it to disable for ten minutes. Claimed if it wasn't the key, it is a weak door lock actuator. Well new key and all five new actuators and the problem still persist. I think they screwed up on the tune up. I guess I will have to take it to a dealer, and get screwed further. Sorry, I know that doesn't help you any.

 

I am having the same issue with my 02 impala. The reason that it is starting after 10 min is because it takes about 10 min for your car to relearn the codes for the security system. I have changed the ignition lock cylinder in mine and have been trying to reset the code but it is not working. I know this doesn't really solve your problem but it does shed light on what else it could possibly be.