first:
In regions where higher volatility fuels are used during the winter to improve the starting of the engine, the use of "winter" fuels during the summer can cause vapor lock to occur more readily.I talked to my mother today in east TN and she said they have had above avg temps way erlier than avg this year, so perhaps the fuel supply is still using a winter blend? secondly:
Most modern engines are equipped with fuel injection, and have an electric submersible fuel pump in the fuel tank. Moving the fuel pump to the interior of the tank helps prevent vapor lock, since the entire fuel delivery system is under positive pressure and the fuel pump runs cooler than if it is located in the engine compartment. This is the primary reason that vapor lock is rare in modern fuel systems. For the same reason, some carbureted engines are retrofitted with an electric fuel pump near the fuel tank. A vapor lock is more likely to develop when the vehicle is in traffic because the under-hood temperature tends to rise. A vapor lock can also develop when the engine is stopped while hot and the vehicle is parked for a short period. The fuel in the line near the engine does not move and can thus heat up sufficiently to form a vapor lock. The problem is more likely in hot weather or high altitude in either case. sounds to me that with our fuel setup, because the pump is pushing the fuel rather than trying to draw it up the lines that it would be less sensative to vapor lock (ie it wouldn't cause the pump to draw up air and cavitate), but that you could still get a small amount of vapor in the lines. IIRC our evap system vents from the fuel tank and not from the lines near the engine, so it seems unlikely that retaining it would help with your problem. sorry I'm not more help.
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