Trying to understand vapor lock

[bmohan55]

2.25 petrol in good shape
New tank and fuel pump, new lines correctly routed (in front of water pump), rebuilt Rochester carb and new fuel filter.

On the way back from a rock crawling event (won’t do that again!)I was pushing it hard going through the mountains of Va near Charlottesville. Truck was running strong, maintaining between 60 to 65mph and only having to shift out of overdrive on one climb. Temperature gauge read slightly above normal, needle at the top of the “N”. After stopping for fuel at the half way point, I took on 10 gallons. Getting back on the highway it died within a half mile. I’ve fought vapor lock before so I recognized the symptoms. The fuel filter right in front of the carb had fuel, I pumped the fuel pump and watched fuel load in the filter but still wouldn’t run. So I sat by the side of the highway for 20 minutes until things cooled down. Started it up and after a few minutes of rough idle I completed the last 60 miles with no problems.

After reading the related posts can anyone suggest a fix short of an electric pump with a return line? Was it the “cold” gas and “hot” motor not agreeing?

Thanks

[scott]

i hate this vapor lock mystery too. what i think it is is the fuel warms to a point where it's moving from a liquid to a gas and when it's in this state it doesn't mix well with the air being sucked into the carb and the mixture is so lean that it doesn't burn.

i have installed an e pump and will be adding a return line such that when the float valve closes fuel moves back to the tank. this should keep the pressure from being compressed between the pump and a closed float valve to a minimum as well as keeping the fuel cooler from remixing with the fuel in the tank.

i suspect that fuel under pressure and warmed by the heat of the engine bay combine to cause vaporization. but i'll be the first to admit that i'm just guessing at all this crap.

i have a weber 2 brl and the literiture on it says they like fuel pressure between 2,5 and 3 psi.

[1961 109 WAGON]

where did you go, the cove in winchester?

[bmohan55]

Crozet, a private rock park had an open wheeling day. It was nuts, very much over my head and under equipt...mud tires do not grip at all on slick rocks, I have 4 new dents to prove it!