[AnthonyG]

Hi Allen & Thx for the reply! I’m not sure how you mean apply vacuum? I thought the actuator arm operating up & down as the cam does with the fuel pump rod did that? If that’s what your referring to I did operate it at approx the speed I saw the rod reciprocating ant even faster many times with no vacuum or on the output side pressure readings on output side. Also as I try what I think is practical, I fed the pull side into a can of gas with bowl held vertical pumped actuator again many times with no gas pulled into the bowl. Then one more try at putting the output tube in liquid to see if any bubbles while pumping & none. By apply vacuum did you mean actually hooked up to carb with engine spinning to create manifold vac wth carb sucking too? If yes I guess I misunderstood how to bench test. As original post said, unbelievably after 55 years working on my cars & engines I never had a problem with or occasion to test a fuel pump🤫😬😂! I ordered the prewar pump with no bowl not because of this but to get a bit more room as it got kinda busy back there with the bypass oiler installed.