Vapor Lock with FI motor?

[wrogers55]

Bad experience today. About 90 here in Texas. Got caught on a backroad construction and had to move through a few miles at 10 or so MPH. The motor didn't overheat but it was sure hot under the hood. After about 15 minutes of this, the car started to starve for fuel and slowly quit. I let it cool off a bit and it would start fine and run for a short distance and the same thing over and over. Finally decided on a flat bed tow home.

The motor is a 418 SBF MassFlo EFI and has run perfectly for years. Here is what I know so far from the side of the road only.

1. The fuel pressure gauge at the motor would not move when the pump was on at first then would suddenly build pressure. The pump would change tone from freewheeling to labor and I had pressure and it would fire off perfectly. Tank was half full.

2. While it was shut down and not running, I opened the gas tank filler and could hear "bubbling", like the return line was putting vapor back into the tank and causing bubbling.

By the time I got home, and unloaded, it started right up, had good pressure and I drove it onto the garage with no problem.

I'm going to start at the tank and work my way forward but is it possible the fuel rails got hot enough to boil the fuel and cause the problem? Not sure that would explain the pump spinning up without building pressure for a bit but maybe the return line is involved too. Any thoughts would be appreciated as I start down the fixit road.