Hot start and idle issue

MeanGreen · October 29, 2003

I'm having an idle and hot start issue with my '99 GMC Sierra with the 5.3 liter V8. When the engine is cold it starts up just fine, but if the engine is hot and the truck has sat for more than 10 minutes or so, It will take 5 to 10 seconds before it will start up. Less than 10 minutes and it starts fine. Also when I'm driving and come to a stop the engine will die sometimes just as the truck stops and it does idle rough as well. It sometimes lurches forward when stopped with the truck in gear and my foot on the brake pedal like its trying to accelerate. These problems occur more as the air temperature gets hotter. The fuel pump seems to be working, I turn the key to run and can hear it for about 2 seconds. I have replaced the fuel filter, vapor recovery canister and the purge solenoid valve. Anyone have any ideas what could be wrong?

ParkRat · October 29, 2003

Do you think the O2 sensors may need replacing?

MeanGreen · October 30, 2003

It hasn't thrown any codes for the O2 sensors. Just for the occasional cylinder misfire, usually during startup.

Shaners · October 30, 2003

Some people have had problems with the fuel regulator. Maybe your truck is a victim too.

MeanGreen · October 31, 2003

That's what I was thinking also, after reading some other threads on this forum. Thanks alot...

Shaners · October 31, 2003

It proabably wouldn't hurt to give the MAFS a good cleaning too...

MeanGreen · October 31, 2003

I periodically clean the throttle body with TBI cleaner, but it hasn't made any difference. Can I use the TBI cleaner on the MAF sensor or will it damage it?