Battery good starter good but will not start - Avalanche Chevrolet Cars & Trucks

The two usual reasons a car won't start are either lack of fuel or lack of spark (ignition). Pull a spark plug (pull off the plug wire boot, then get a spark plug socket and a ratchet handle and unscrew the spark plug). Reconnect the plug wire to the spark plug and hold the metal base of the spark plug against the metal valve cover or the engine block (something grounded) while someone else cranks the engine over with the ignition switch for a few seconds. If you don't see a spark jump the gap in the plug, you have an ignition problem. If you do have a spark, it's probably either lack of fuel to the cylinders or a timing problem that is causing the problem.

Hi there!
I dont know exactly what car you have but I would say check the crank shaft position sensor and the cam position sensor because when the two parts fail the starting problem appears. Good luck