sounds like the same prob i had,

check all the obviosu stuff and couldt find anything,,,,

turned out that the 2 thin red wires that come from the pos post of the battery then go into a larger red sheath that go along the top of the bulkhead... the copper had work harderned and snapped inside causing the pump not to run and symptoms as above. the insulation was intact though,,

only found it my mistake when performing a 'waggle' test had to chop back about 6" then add some new ends on, prob a lot like this with having the battery moved etc as its where they get bent back to make room, worth checking