Its a little confusing. If you have any resistor in the ignition system. Not good. (BTW, resistors are not voltage specific). You have two fuel pumps working, not good. Have you checked the flow when hot and won't start?????? This answer is very important. This test is done by observing the flow out of the outlet of carb to see pulsing good squirts into a clear bottle. Otto's test to see gas being squirted down throat is good also.
When electrical wires and ignition components get "hot" they get high resistance and less current/volts to the points/plugs. This is due to a lot of bad connection places and corrosion. Weak gets more weak. A weak battery gets weak when hot. Heat caused by Bad timing. Exhaust manifold leaks. Lack of motor cooling....So this would be your "electrical or heat" cause. Weak spark.
The concern about switches, coil, carb, pump must take into consideration that the truck
does start.
Sooooooooo......
I don't believe "hot" or electrical has anything to do with it. You had the same problem with mechanical pump as now...so my
guess is Gas Tank venting. You are pulling a vacuum in the tank and fuel eventually stops and it seems like hot but it's just the time it takes to pull a vacuum lock. The electrical pump was steady and stronger for a while. The truck starts after sitting and bleeding off the vacuum as tank debris clears/floats.... or a blockage of some kind bleeds off vacuum. It is not "cooling down". Take off the gas cap and drive it. See what happens. If it works, drill a 1/16 diameter hole near center of cap.
If flow test is bad, then there will be a list of things. Mostly not related to "hot" or "electrical"
1. Debris at tank pickup.
2. Fuel line collapse or block in line or valve.
3. Fuel filter
4. Carb components
5. Tank vent
6. Bad pump
If flow test is good, report before continuing.
The flow test/carb pump test and cap removal are easy and fast to get a clue. During "won't start"
it's good to see some spark at a plug.Can you advise "won't start"?
Motor does crank but no fire at all?
No sputter?
NO backfire? Thru carb or exhaust.
Choke no help?
No gas smell?
Gas tank has at least 1/2 gas in it for sure.
Squirting a shot of gas down carb from a spray bottle gets no fire? Do this if bad pump test or observing dry throttle pump (Otto)
Don't take this the wrong way, it is just part of the diagnosis. I realize you are trying things. However the mention of resistor, two pumps, check valve, switch to turn off E-pump, new carb kit, new coil.... means it is possible you bypassed the cause and have introduced, off and on, some other causes which now all need a rethink/eliminated.. This is what everyone is sorting thru now.
