if you pull the pump and jam a screwdriver in there and rattle the eccentric around, it should not move on the camshaft. If it does...its loosey goosey. I dont know what the clearance is from the front of the eccentric to the case but if its a few mm's then if the bolt has come loose, the eccentric may be riding the cam key just enough to ride on the inside of the case too and somehow keep cycling the fuel pump. That would be crazy if that was the problem!
