No start when hot outside problem, 93 civic

My friend's Honda civic won't start when it hot outside. He believes
the main relay is not closing (no clicking) when this happens. He
removed the relay and we checked it on the bench. It closes reliably
with 12 volts even after baking in the oven a while. The solder
connections look find but we retouched them anyway. He's putting it
back to see. I expect the problem will return and the relay seems
solid.

When he has the problem, it seems that there isn't even a sputter.
Completely dead. If he lets it set a while it starts okay then. He
believes the main relay doesn't click and fuel pump doesn't do the usual
start up noise. I'd check for fuel pressure on the rail, but there
isn't any access port. Is there an easy way to check this?

I've read elsewhere that the ignitor can be a problem. Someone else said
try a new reluctor. However the problem seems to relate to outside
temperature, not to under hood temperature. I was thinking a crank pos
sensor. We have no diagnostic tools to check these things.

I guess I should also mention it is cranking nicely, just not starting
or even stuttering. If it starts, it runs just fine.

He's worked the ignition key when this happens, so we don't think the
ign switch is bad.

Are there any other common issues with this model that cause it to not
start when the cabin of the car is hot?

 

Just the main relay failing
Steve

 

go to any electronics store and buy an can of "cold spray". when the
car won't start when its hot, give the main relay a good spray of this
stuff. thats how i confirmed my main relay was bad.