Hard start when warm

[millardjd]

Hi I have a problem with a 2004 GMC Yukon, it starts great when its cold or has sat for a while. When it has run for a little while it will not start, it acts like it wants to start but will not stay running. i thought it was the fuel pressure regulator, and i changed it, but that did not help the problem. I wanted to see if anyone had any ideas on what the problem could be. I have not checked the fuel pressure yet,but i dont have any ideas what it could be at this point. Any advice or knowledge would help, thanks!!

[Jsdirt]

In the old days of carburetors and points ignition, those symptoms would tell me the truck is either running too rich, or has a failing ignition coil. As far as combustion goes, nothing has changed since those days - just the control systems for fuel and spark have.

 

If the check engine light is on, post back with the code. Otherwise I'd investigate whether or not it's getting too much fuel (for a myriad of reasons on OBD-II vehicles), or has a failing ignition (less likely today as each cylinder has it's own coil pack).

[millardjd]

I dont have the code numbers in front of me but when i did hook it up, I had an engine coolant temp message, which i changed the sensor on, and I had a code for the evap system, Also i think there was an 02 sensor that popped up there but that hasn't caused any problems since that was the first code that had come up a couple years ago.

[lee123]

If its cranking fine, fuel pressure may be next

[Artey72]

Possible leaking fuel pressure regulator.

[Colossus]

betcha it's your fuel pump. Time to drop the tank and replace the module.

[8.1HD/ALLISON]

+1 on checking fuel pressure.

 

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[RyanbabZ71]

+ infinity on the FPR (fuel pressure regulator). Same symptoms on my 2000. $50-60 and 5 min problem solved

 

 

Ryan

[8.1HD/ALLISON]

Said he already replaced fpr.

 

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