Problems Fuel pump in high temperature.

[ford38v8]

Harylufa, To "test the coil heat", the next time your engine fails, pull a plug wire and hold it to a head stud to test spark while you crank it over. A good coil will deliver a strong blue spark about 1/2" long. A weak coil will show a smaller orange spark or none at all. This same weak coil may show strong when it is cool again.

Generally, a fuel pump diaphram should not stretch when it gets warm, as they are made of reinforced material. An older diaphram may be subject to permanent damage by fuel containing alcohol. Newer diaphrams are made of fuel resistant material.

Your modified pushrod may be of an incorrect length. Check the pump's rocker pivot for damage that may indicate a rod that is too long. A rod that is too short will not depress the rocker sufficiently to actuate the pump. Remove the fuel delivery tube from the carburetor and direct it to a glass jar while you crank the engine with ignition off. You should get a strong pulsing flow from the pump to the jar.

As was said earlier, both a fuel related problem and an ignition related problem will produce identical symptoms, but it is important to address one problem at a time so you will not inadvertantly create a problem where none exists. Don't jump in and do several things, as you will not know which was succesful and which was not.