Pontiac Repair: Missing on hot startup - 1996 Bonneville SE, fuel pressure regulator, crank sensor

Question
hi Todd,

i have a 96 Bonneville SE 3.8L, and its having problems starting up after shutting her down when hot. To me it feels like its flooding once i get her up and running because once shes on the road all cylinders will then run. i usually smell gas once im out of the car whens shes off.
Things iv done:
Tested and working... Fuel pressure reg. (lines dont have fuel in them), MAP , MAF, fuel pump,TPS, new plugs & wires , new coils & module, new UIM & LIM gaskets, wires to the PCM

Im now thinking bad connection to either the crank sensor or cam sensor, could it be the O2 sensor?

BTW runs perfectly fine once shes driving

thanks in advance
mark

Answer
Hi Mark:

get it hot and let it sit for say 10 minutes. then pull the line off the fuel pressre regulator and make sure ther is now raw fuel in there. You could have an injector(s) that are leaking when off and the engine "floods" out. I would do a pressure test on the fuel system after the key is shut off the pressure should hold and actaully rise a few pounds when it's good and hot. It should not bleed off rapidly. If it does you have a leak, Fuel pressure regulator as mentioned before or it's bleeding the pressure off back into the tank. the check valve in the pump could be bad abd the pressure is bleeding back into the tank. Or injectors that are leaking. A  easy way to check that is to pull out the rail leave the fule lines attached and set the rail down on some paper towels turn the key to run and let the fuel rail pressure buld up and then turn the key off and let the rail sit on the paper towel if any of the injectors are leaking you found the problem.  What I think is happening is either the leak is into the engine or back into the tank and the fuel that is left in the rail is vaporizing and causing a vapor lock gas engines do not like to run on fuel vapor they need raw fuel to run. So that is where I would start looking. A o2 will not cause a hard start issue. a crank sensor will cause a stall or no start at all. good luck :)