All these tests, volume, pressure, and vacuum, depend on the engine being able to idle on the fuel in the float bowl for a short time- - - - -30 seconds for the volume check, less than half that time for pressure and vacuum checks. Any engine that won't do that has far worse problems than a flaky fuel pump. I've been doing that test since the early 1960s, so I'm not just parroting some pie in the sky theory from somebody's website. I try to share real world facts and figures that have served me well for decades. Maybe that comes from being the middleman in 5 generations of mechanics- - - -from my grandfather in the 1920s to my grandson, who is currently making a living fixing cars. His 3 year old daughter had her tricycle turned upside down on the floor a few days ago, "working on it!"
Jerry
