Truck Repair: Hard Cold Start 2001 Silverado, chevrolet silverado, pressure tester

Question
2001 Chevrolet Silverado 5.3litre gas, auto trans, 48k miles.

When warm, shut off engine, will start right away.

When it has been sitting for 30mn or more, may crank 10 seconds or so and then do a slower almost sputter start.  Sometimes able to get it to fire right away by cycling the key forward 5 times (to run the fuel pump)  When this process works, the noise I hear when advancing the key is that of a smooth zzzzt.  (sounds like a fuel pump providing a nice clean push of fuel)

When this process doesn't work, the pump type noise I hear is more of a gggggg, like that of a gear spinning and not quite catching.

Pump? Module?  How to diagnose?

Thanks,
Steve

Answer
Hello Steve,
Those are some great noise discriptions.
Is there any difference in the noise between when the tank is full, and empty?

Sounds like the fuel may be leaking back into the tank. A fuel pump may be in your future, but I would like to connect a fuel pressure tester first, and see what it says in each situation.

Some injector cleaner run through the tank could also clean something out.

Van