I really dont think its you... sounds like they have
a by-pass spring issue.... you put on 2 different pumps
only to have the same issue... I would say that takes
you out of the problem... you could cut the by-pass
spring down some.... or take the spring out of your
old pump(from the original pump that worked) clean
it and install it in your new pump.... and make sure
the little piston/cup moves freely