Question for Either TheFermanator or Spareparts or anyone else that might know.

[THEFERMANATOR]

When you have an engine with a good differential pressure in the crankcase, the pulse type vacuum pumps work great. Also they draw virtually no HP from the engine since the moving parts are driven via crankcase pulses instead of a mechanical means. Also factor in that magneto type charging systems put out virtually nothing at idle, so the fuel pump running at idle will pull the battery down a good bit at idle. i know my old 140 would put out less than an amp at idle, but push 9 amps or so at 5K. The thinking was if you didn't need a better mousetrap, why re-invent the wheel.