Vapour Lock Issue

When it starts to splutter I nail the accelerator to open the mechanical secondaries and it takes off again till the fuel runs out in the secondaries then it just dies. I pull to the side of the road and crank it over for about 20 seconds and then it will fire up again.

Prior to installing the bypass reg it was real bad to the point where it would only drive for 2 miles and then stall, get it going again and have the same issue mile after mile.

Thanks for all the replies so far.