03 Silverado Problem

[bleach]

03 Silverado 4.8Vortec- Usually takes 2-3 attempts to start. Turns over good, just doesn't fire.
After 3 trips to 2 dealers, new battery, plugs/wires, ignition coils...same problem.
Any suggestions?

[bill190]

Check the basics, Fuel, Spark, Air.

Fuel: While someone is turning the key to start, have someone else spray starting fluid into the throttle body. If you get a response, then this is a fuel problem.

Spark: Remove a spark plug and place the side screw portion against a piece of body metal or engine metal (grounded to battery negative/ground). Then watch as someone turns the key to start. See if there is spark. Advanced spark testing is to use a spark testing tool which would typically have a gap of .25 inch. You should see a crisp blue spark. This is a larger gap than a spark plug and tests that the coil is producing a high enough voltage. (Good spark as opposed to weak spark.)

Air: Slightly press on the accelerator while trying to start. Normally the throttle is completely closed and the IAC (Idle Air Control) valve adjusts to admit air into the engine. By pressing slightly on the accelerator, you are bypassing the IAC valve and allowing air to enter the engine.

Combination test: While someone slightly presses on the accelerator and turns the key to start, have someone else spray starting fluid into the throttle body.

[bleach]

I tested fuel and spark previously and were good, however I haven't tried bypassing the IAC.
Thank You.

[Z71_guy]

have you checked your fuel pressure regulator yet? Left side (drivers side) of motor about midway just under the plastic cover pull the vacuum line off and if any gas what so ever comes out replace it, if no gas comes out right away let it sit with the vacuum line off for 5-10 min and then look for residue seeping out