Just wondering ... would it help to solve this problem if you installed
a switched fan, thermal/manual, in one of the D-post cavities?  I don't
know if it would be best to exhaust heat or blow air into the engine
cavity.  A reversible fan would be nice.  Or maybe it's a question of
insulating the fuel tank?   Could you run the return fuel line through a
heat exchanger?
-Dana-
 ...
> Identical behaviour to older cars with fuel vaporising before the carburetor.
> Both the pump and fuel lines would be too hot to touch at this point.  A new
> (expensive) pump improved things a lot, but on extreme heat days, it still
> hesitates after idling. A half hour rest to cool down (good for the driver too!)
> puts things back to normal.
 ...

> > gasoline formulations, combined with hot weather and fuel pump pressures,
> > the cars suffer from 'vapor lock'.  He's also found that when he rebuilds
> > old Beetle engines he needs to install a fuel pump in the front tank to
> > provide the pressure to get it to the engine (plus a regulator to reduce it
> > to the correct pressure in the engine).
> >
> > We've had many fuel pump failures on our Jetta since 1986 and the 'no start'
> > mirrored the fuel pump failure.  Of course, I panicked!
> >
> > The point to this is that severely hot temperatures 100's+ dry, 90's+ humid
> > will affect the density of gasoline and your fuel pumps.  So be careful.
> > Every time the fuel pumps failed in our Jetta, the temps were extremely high
> > for the locale:  108 in Kansas, 102 in Florida, humid high 90's in New
> > Hampshire.