496 overfueling
 

what would cause a 496 h.o. not start after a half hour run,,,it will run great,,,but after a run,,,if you try to start it,,,it wont ,and you can smell raw gas,,,map, coolant sensor,e.c.m.,cam sensor,crank sensor,have all been switched,,,,i.a.c. replaced also,,,,would a bad fuel pressure regulator on the rail cause this????the one at the cool fuel 3 has been replaced ,,fuel pressure on rail is correct,,,it like when its hot,,and you try to restart it ,,,,its dumping way to much fuel for it to start,,,merc techs are stumped too

Does it hold fuel pressure (engine off). For how long? Have you done an injector balance test? If the fuel pressure at the rail when its not starting is correct, forget the regulator.
My guess would be a leaking injector.

You should check spark (just to cover the basics) when it doesn't start, also pull a plug and verify its wet, sometimes chasing a rich condition based on odor can have you barking up the wrong tree.
If all else fails do a compression test, to make sure a valve isn't hanging open or something very abnormal.

pressure does hold at rail ,,,,ill verify spark torommow,,,thanks for the advice,,,the crazy thing is if you start it cold,,,let warm up,,,and go for a 1/2 hour ride its perfect???gets hot and wont restart,,,or if it does its runs like its on 5cylinders???

heres a update,,,hooked up computer,,,and iac,,not moving at all,,,no vacuum when u pull the hose off the throttle body,,,so its either a plug intake,not letting the iac work,,,or will have to do a compression and leak down test,,,,:eek:

How does the oil look?

oil looks good,,,no milk shake

Could it be a bad coil? Maybe overtime the coil over heats and doesn't deliver the spark. Then when the coil cools, you are able to start again. Just a thought.

its in the valve train,,,we used a vacuum gage on it today,,and it reads low, 6 in vacuum,and the neddle is bouncing around,just glad its not in the bottom end:cool: