cowboy44444

Truck runs fine till its warmed up good, then dies like its vapor locking. Replaced the pump in the tank and plan on replacing the pump on the rail. When it quits running I have cycled the pumps(turning the key on and off ) then bled it on the fuel rail. Lots of air comes out but the gas coming out is cool to the touch. After the truck sits an hour or so it runs fine again till it warms up again. Its a 5.0 Any ideas would be appreciated. Thanks!

5Rangers

Your going to want to check fuel pressure also does it do this from both tanks?

cowboy44444

Checked the pressure and it was within specs. Problem exists on both tanks.

5Rangers

Interesting... fuel pressure within specs when running from both tanks and the problem is not related to one tank of the other. I wonder if you have any fault codes in the EEC.

The 300 6 cylinder engines have a system that blows cool air on the rail after engine shutdown to prevent vapor lock. I removed mine and have had no problems. I am not sure if the 302s have this system.

What I find interesting is the amount of air you are able to keep bleeding out of the shrader valve. I can't understand how this air is induced because the system is pressurized throughout. How could air get in, any hole in the system would show as a leak.

You can check the FPR fuel pressure regulator easy enough. Pull its vacuum hose and check for the presence of raw fuel.

I wonder if you unplug the high pressure pump at the pump and then activate either one of the in tanks if a leak would reveal possibly in the area of plumbing upstream the hp pump. Seems like its has to be pulling air from somewhere..