i have checked everything i know how to do.my car when sitting a while hot or cold it takes a few seconds to start.fuel pressure regulator is fine what is it i bought a cam sensor hope it will fix it. but what else can it be?
The problem might be with the fuel pump check valve. This check valve prevents the fuel from draining out of the fuel rails/fuel line back into the gas tank.
To determine if this is the problem, the next time you go to start the engine, just turn the ignition switch to the run position so that the dash lights come on for two seconds and then turn the ignition switch off. Repeat this a half dozen times and then try starting the engine. If the engine starts right up, the fuel pump check valve is leaking as the vehicle sits for an extended period of time.