I know this has been a common problem for a lot of people and not just the Q-jet guys. Maybe one of the most common problems nowadays. I had this problem on my pontiac motor and it turned out to be heat soak in the fuel pump.I switched to a mechanical pump and ran the fuel line a different route that was farther away from the engine. I also used fuel injection hose instead of the steel line because it insulates the fuel better. it worked. If you could figure a way to get rid of that heat under the hood that would be good also.An electric pump works it just can not get hot. same goes for fuel lines. tiny bypass is anither idea to help with the vapor lock. It seems like accal pump shot would start the engine but that is not always the case when the engine is hot. BTW, that fuel injection hose (9R I believe) is PRICEY.
After it gets hot, if you let it cool down, how does it start then? IMO, fuel vapors must be minimized as much as possible with this crap that they call gasoline these days. Sure it works just fine with fuel injected cars with 44 psi line pressure and bypass systems and fuel injection. Carbs with low PSI and no bypass (to keep the fuel cool) is not so good. Also, if you still got the mechanical pump on it, remember the quality of the pumps has gone down hill in some cases due to decreased demand for them. So, just some things to ponder. my .02
