could a defective air pump cuz an LT1 to not want start until its crank for several seconds?

 

The air pump has nothing to do with the engine. It is used to heat up the cat's quickly. Your problem is probably from a defective check ball in the fuel pump sending unit. It is not holding pressure as long as it should and is allowing fuel to draw back toward the tank. It then takes a few more seconds then usual to start the engine.

To test it simply turn KOEO for a few seconds the next time you try to start it. Then key off. Then KOEO again for a few seconds. Do this cycle about 5 or 6 times and after the last time, then attempt to start it. If it cranks up right away, that is probably the problem.

You could also monitor the fuel pressure to come to the same conclusion. If the gauge is on while the engine is running then once the engine is turned off, the pressure will drop fast. If it sits long enough while not running you will then notice the pressure rise a little bit each time the power is cycled on and off as described before.