Finally got a chance to screw the pressure gauge I got into my FPR. When I started it up the needle jumped back and forth between about 40 and 80 PSI at idel. Is it normal for it to jump back and forth like that? Got a new fule pump. Was thinking when the tappet is pushed up by the cam the pressure will rise and then drop when it comes down. Havent had a chance to get somone to step on the gas so I can see what the gauge dose at higher RPM. Shouldnt the pressure stay even with rpm?

 

Yes it will flutter with a mechanical fuel pump.

Bill

 

it will get a little better at roughly 1000-1500 rpm but it will never be smooth as an electric pump is.

 

Ditto the above. A liquid filled gauge will dampen some of the fluctuations.