Basically, you would just raise the boiling point a few degrees by adding pressure.
You probably have a weak mechanical pump.

If you are saying you have an electric pump and a mechanical pump working in series, that would be a problem. They need to be run in tandom. They need to be T-ed before the mechanical and then T-ed again before the carb. Running the two like this works great! I run them that way for using Nitrous Oxide. When using NO2 a lack of gas is a detenation. Can you say, "There goes my carb, it's a UFO"!