djkeenan

"I can’t see any reason for the regulator to work cold but not hot, the unit is little more than a spring acting on a diaphragm & when the pressure is reached the valve opens & fuel is returned to the tank."

I hear what you're saying but maybe this isn't a problem caused by overheating but caused by a certain situation i.e. the fuel system doesn't work properly if its primed after the engine being run recently. Something is not resetting to default causing the fuel to not get to the engine?

What's frustrating is the fuel was spraying every time I cranked the injectors while outside of the engine. I can only presume something is different inside the piston heads. Although I would assume the pressure in the head is very much the same as outside the engine block when first cranking?