At 07:03 AM 6/4/2007, you wrote: >A pump pumping at 8 to 10 pounds of pressure is required >for a large engine...6 - 8 cylinders?...while the 3.5 to 4.5 psi >pumps are required for the smaller engines...4 cyls and less? >TL ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
To be a bit more accurate, it's based on carb design, not engine size. The carb on my 0-200, which came from a C-150, is set up for a fuel pressure in the 3 to 5 pound range. I don't recall the exact numbers but I think a pressure of maybe 6+ pounds requires a modification to the carb. Same engine. It's based on the ability of the float to close the inlet needle with enough pressure to shut off the supply of fuel and maintain the proper level of fuel in the bowl. The carb used on the Harley engined Zenith 601 that a friend built needed the regulator set to 1.5 pounds to keep the pump from flooding the bowl. Each carb has it's own design numbers. I run dual low pressure Facet pumps. Unsure of their exact pressure, even with a fuel pressure gauge, I simply installed a fuel pressure regulator in line and set it to 4.5 pounds. It's worked for 280 hours now with no problem. Larry Flesner
