98 sierra p/u 305 vortec trys to fire but dies let sit 20-30 min. and would start know that dont work trys to fire but less than befor new ign. control mod and starter what else could it be?

5 fuel pumps and 2 motors? id say that whoever is diagnosing your car needs to be fired. toggle switches, over heating, stalling after 30 mins, new motors....you need to get this to a shop. no way someone can diag this cars serious problems and over internet.

I’m happy to assist further over the phone at https://www.6ya.com/expert/josh_8f8ad0a8f7e0e6d3

3 things keep a motor from starting.1. NO SPARK, 2. NO FUEL,. 3 ENGINE DAMAGE. I SUSPECT IT IS THE IGN MODULE WHICH IS INSIDE THE DISTRIBUTER. cHECK TO SEE IF IT HAS SPARK.. iF IT DOES THE IGN MODULE IS NOT THE PROBLEM. iF IT DOES HAVE SPARK CHECK TO SEE IF IT IS PUMPING FUEL.. DO THIS BY SQUIRTING A LITTLE FUEL INTO THE INTAKE MANIFOLD THROUGH THE INTAKE AIR HOSE RIGHT BEFORE IT CONNECTS WITH THE INTAKE MANIFOLD. .. iF THE MOTOR FIRES AND TRYS TO RUN YOU KNOW FUEL IS THE PROBLEM. IN WHICH CASE IT COULD BE A CLOGGED FUEL FILTER OR A INOPERTIVE FUEL PUMP. iF IT HAS FUEL AND SPARK LOOK FOR A BROKEN OR STRIPPED CAM TIMING BELT. NOT TURNING THE CAM OR CAMS.

Did you put stablizer in the gas before storing it? Does the fuel pump run for 2 seconds when the ign is turned ? Have you checked the air cleaner for debris? Do you have spark? You must have air/fuel/spark to start.

Sounds like it could be a dirty or faulty idle air control valve.Take it off and clean it with a wire brush and a non-chlronated brake cleaner or replace it with a new one.Make sure you reset the computer after cleaning or replacing the valve.

A fuel filter won't clog completely in 3 years
and won't get you down to 15# if it did

What is fire?

Voltage to pump or ignition spark?

What about pressure regulator?

check you mass air flow sensor be careful that you dont get gas on that sensor. or its you brain

simpler that exposing the throttle body just depress the accelerator 3/4 and try to start.

If like before, the vehicle starts... watch the rear view mirror for black smoke

both indicates a leaking injector(s)

battery is very low I aqssume from trying to start it so many times. have the ignition module checked out
that maybe your problem if its very old. it is located inside the distributor

I AM LOOKING AT TIMING ISSUES OR INTAKE MANIFOLD LEAK.OR EGR VALVE STUCK OPEN.

Try a new distributer cap and rotor button before you go any further.