Could be a few things if its a no start when the engine is HOT,
One, to much fuel after it is shut off. The float can't hold the pressure of fuel heating up, fuel then overflows into the intake creating a over rich mixture. After ten minutes the fuel has evaporated, the truck starts like normal. Mine has a five or six minute window where it will fire right back up depending on how hot the motor is and how hot it is outside, if I miss that window of time, in ten minutes it will fire right off. In between these times, it cranks for awhile to clear it out.
Two, not enough fuel. The tank slowly builds a vacuum due to poor venting or wrong cap, or the fuel pump heats up and can't pump due to leaking valves. Theres no fuel in the carburetor, so no start. The tank will bleed off the vacuum over time, or the pump cools off and it starts ups. If it's the pump, your electric should be able to blow through the mechanical and the truck should start, but the electric may not be able pull fuel if the tank is in a vacuum.
Three, the ignition condenser or coil is going out from heat. Once either one cools off, the truck starts as normal.
The fact that it starts with starting fluid would lead me down the fuel road, starting fluid has no effect on ignition. You need to look down the carburetor before trying to start it to see if it has fuel or not.
