Mechanics

TRUCK STARTS FINE WHEN COLD, DIFFICULT STARTING AFTER IT IS TURNED OFF AFTER IT IS WARMED UP. 4.8L ENGINE

1999 GMC Sierra • 107,000 miles

Bought the truck 2 months ago. Replaced plug wires, plugs tuned @ dealer. Runs great. Just trouble starting after it is warmed up.
Avatar
Gwaleyd
October 28, 2011.



Hot or Cold-Do below

Next time it refuses to start don't wait for it to make up its mind-do below immediately to determine if its fuel or spark problem

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 3/16 away from ground-have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, Do you hear the fuel pump come On when you turn key on? If not check fuel pump fuse and fuel pump relay if okay-check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, coil's resistances, cap and rotor, distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it and keep testing

Rasmataz
Oct 31, 2011.