1 Ton YJ Crawler build

[ryan]

I don't know much about Jeeps but I do know fuel systems... Does the rail have a return out of one end and supply on the other with a regulator on the rail? That's the BEST setup for vapor lock assuming the fuel pump is in the tank, if it's not it needs to be as close to the tank as possible and as low as possible. If external pump and only a single pump system it's best to get a low pressure pump to put first in line (the marine Carter/Sierra is a good one, or as good as you'll get). You want to get liquid fuel through the fuel rail and flushed out so it can cool off. The heat shield and louvers should help your situation though.

Yeah, the 4.0 was basically designed for vapor lock. Fuel pump is in my fuel cell, but the fuel rail sits directly next to the valve cover and above the exhaust manifold. Combine that with what I think was a sticky thermostat so that it was running a little hot and the temps were wild. Water was cooking off the fuel rail