NO START WHEN CONNECTED TO OLD/NEW FUEL PUMP

[Sam]

I help a lady friend who has a 77 27 ft Oday with late model A4, EI, 5 bolt carburetor and due to tight space a smaller "posi flow" style electric fuel pump. I winterize their boat and usually it is a easy routine start up in the spring. This year was no joy. The A4 sputters well with starting fluid, runs very well with good throttle response with auxlliary tank on cabin top with syphon line using gas that was pumped from the bottom of the main tank. Even though the engine mounted off brand fuel pump pumped a fair amount of gas I suspected this to be the culprit and change out to a new Facet posi-flow #60104 1.5psi-4psi. The new pump pumps fuel well but when connected to the carb the engine does not start. I can immediately use the auxiliary cabin top tank and it the A4 starts immediately and runs well. Hard to believe I have two bad pumps. Ordered a fuel pressure gauge but not thinking this will solve the problem.

I am a little stumped in my old age - missing something. Runs on the auxlillary tank well - not on a fuel pump. Changed filters andI removed the carb and gave it a good cleaning but did not split it half since I did not have a new body gasket- float is not stuck, no leakage and carb is dry. Has been trouble free for years with the smaller posi-flow pump [ space constraints make it harder to use the larger Facet pump - ran fwell for years with the smaller pump]. Any suggestions