I've had this problem for a while now and would like to know if anyone else may have had this problem before and what the diagnosis was.Starts fine from dead cold,a little stumble at light throttle until warm and then it will run fine.Stop the engine and let it sit for more than five minutes and it takes ten to fifteen seconds of cranking to kick off,this has to be hard on the starter and a little embarassing at times.I have not taken any fuel pressure readings yet,I was hoping someone else may have fixed a similar problem before I started on it. Leaking injectors-IAC.-EGR?

 

Put a fuel pressure gage on it and see how fast the pressure drops when the engine is shut down. Chances are good that an injector(s) is leaking and puddling in the intake and you will see the pressure drop quickly. It takes several cranks to burn off the puddle. Since you start fine when it's cold, it is not fuel leaking back toward the pump but rather the fuel puddle is evaporating when sitting for longer periods of time. Pull the vac line off the fuel pressure regulator and see if it is wet. If so, your problem is the diaphragm in the FPR has a hole in it.

You could also try starting it when you normally experience the problem by flooring the throttle wide open. If it starts quicker then, that is another indication that the long cranking is from flooding. WOT at start puts the PCM in flood mode and restricts any further fuel.

You could have the injectors professionally cleaned on the rail with something like 3M injector cleaner. I use it and swear by it. The best way is off the rail when they can be checked for flow patterns. Aftermarket injectors are better since they have a better spray pattern however.

 

Thanks for the information. I will check fuel pressures today hopefully and post them. I also have a set of the SLP LSI takeoff injectors but have not installed them yet. I am hoping it is injectors and not the fuel pump, not quite ready to tackle that job yet.

 

Sounds like your on the right track...Id start with the fuel system,then worry about the ignition components getting heat soaked..

 

Finally got around to checking fuel pressure today after installing a new regulator. Key-on/engine-off I get 38 p.s.i. . It bleeds down to 32 p.s.i. with key off after about 5 minutes. How long is pressure supposed to be held in the rail after shutdown?. Also installed LS1 takeoff injectors last week hoping that would cure the hard start problem,no change.

 

F.Y.I . Thought I would close this post in case anyone else has this problem in the future. Hard start problem turned out to be the fuel pressure regulator. When I removed the fuel rails gas poured out of the diaphragm side-not good- apparently flooding the engine through the vacuum line after shutdown.This fuel would dissipate after a few hours and it would cold start fine.I also had all the stock injectors cleaned and serviced and reinstalled them, I did not like the way the LS1 injectors fit. On another note I cleaned the MAF sensor wires ,really dirty,and cured an open loop stumbling problem thats been bugging me.