1999 GMC Safari will not run

1999 GMC Safari with a V6 4.3 Vortec engine and about 130K miles will not run. Plugs and wires replaced, fuel filter less than 1 year old, plenty of fuel getting to engine, plenty of spark available at the plugs and very recent scanner check showing no problems with any sensors, etc. as well as displaying no error or problem codes. It cranks over but absolutely refuses to run. Any ideas?

What happens if you spray some starting fluid into the intake while cranking? I am assuming that this engine is does not have Throttle Body Injection. Can you hear the injectors clicking while the engine is cranking? Is number one spark occurring anywhere near the timing mark on a repeatable basis?

Get back to us with what you find.

Have not used starting fluid, but have used gasoline - and still will not start. Engine does have throttle body injection. Will check on the rest of your answer.