"Sounds to me like a classic example of 'vapor lock'."

Yep. Sounds that way to me too.

But this is not a "design" problem needing a modification to fix it by adding extra insulation. It is not a "Texas" problem either. It is just the normal and commonly expected failure of a part to keep liquid where it belongs after a whole lot of experience doing it well in the presence of fuel and its various additives. Just a tired part, whether check valve, injector, or fuel pressure regulator.

When the faulty part is replaced, the rail will hold pressure after the pumps stop, and no amount of Texas sunshine or engine heat will force the liquid fuel backward past the roller cell pump. That's the reason for the resting fuel pressure test and the time specification, 1 bar or 14.5 psig minimum after 20 minutes.

Of course there are other things that could be affected by the heat buildup under the hood, yes, but the number one starting point is resting fuel pressure.


--
Art Benstein near Baltimore

Be nice to your kids. They will choose your nursing home one day.