Does a mechanical fuel pump vary pressure with rpm?
Jan 24
I have a mint condition Chevette and I’m trying to get this new Weber 32/36 to work. Does its mechanical fuel pump build less pressure at idle than say 5,000rpm?
Thanks for knowledgable replies!
A mechanical diaphragm type fuel pump should give the same pressure at any rpm.
When fuel pressure builds, it holds the diaphragm of the pump down. So at any rpm, if the carburetor doesn’t need fuel, the back pressure hold the diaphragm down and the linkage just operates without pushing any fuel.
If the stock pump isn’t giving you enough pressure or flow, I’d suggest going with an electric fuel pump.
Filed under: Pressure Pumps
A mechanical diaphragm type fuel pump should give the same pressure at any rpm.
When fuel pressure builds, it holds the diaphragm of the pump down. So at any rpm, if the carburetor doesn’t need fuel, the back pressure hold the diaphragm down and the linkage just operates without pushing any fuel.
If the stock pump isn’t giving you enough pressure or flow, I’d suggest going with an electric fuel pump.
References :
Retired Army motor SGT/ASE certified mechanic