2005 Bonneville Intermittent Starting Issues

[rhaltunen]

2005 Bonneville SE. 3.8 liter V6 46,000 miles.

I just purchased the car in September of 2013 and it's in great shape. Over the past couple of months, I have noticed every once in a while, it won't fire right away after turning over. To get it to start, I have to press down on the accelerator once or twice while cranking. The problem seems to occur when the engine is relatively warm. It seems to have no issues after the car has been sitting over night.

[Tech II]

Remove the vac line from the fuel pressure regulator......if you see fuel drip from the vac line or smell fuel in the vac line, chances are that diaphragm is leaking....

On a cold engine, this is not a problem, because you want a rich mixture....on a warm engine, you want a leaner mixture, but that leaking diaphragm would make it too rich.....opening the throttle allows more air to lean out the mixture, allowing you to start it....

If you do not see/smell fuel, could b e a possible MAF sensor problem.......if it won't start(don't press the gas pedal).....stop cranking, and disconnect the MAF, and see if it will start...

Dirty throttle body(plate and bore), and gummed up IAC pintle are other possibilities....also check for a dirty air filter....

Has the vehicle been scanned for codes?