Trailblazer cranks not firing

[Arthur]

I got a 2006 Chevy Trailblazer with a 4.2 in it that cranks over but won't start I put gas in the throttle body and it still didn't try to fire what will cause it not to have fire?

[carriedi]

do you know how to check for spark? Take the easiest coil to reach and unplug it from the wire harness. Remove the bolt that holds it to the engine and pull up the coil off of the spark plug. Then plug the wire harness back on to the coil. (now would be a good time to pull the plug out and see if it is wet with fuel or you can smell gas on the plug) If the plug is dry and no smell of gas, then put the plug back in the engine. If the plug is wet with fuel or you can smell a gas odor from the plug, the engine could be flooded. if not, Have someone crank the engine over and see if the coil fires as the engine crank over. Let the engine crank few rotations to make sure the spark plug should have fired at least a couple of times. If you had spark then you can put the coil back on the engine. Spark should be good.

Have you had thew OBD2 scanned? There could be a code that could help you narrow down your searching for the no start. Crank sensor code could mean the the computer isn't seeing the engine turn over so no spark.

If you have spark and it doesn't start with gas down the throttle body then I would think that the engine could be flooded or you're not putting enough fuel in.

Is your security light on or flashing? Cycle the key from run to off and then back to run. Do you hear the fuel pump and relay cycling for the 2 second prime? Can you check your fuel pressure? Should be 50 to 57 PSI.

check those things and get back to me if you haven't found a the problem after those checks