I have a 1999 Evinrude Ficht 150. The vapor separator fuel pump keeps sliding up on the shaft exposing an o-ring and spraying gas. I pushed it back down in its slot and strapped it with a plastic tie wrap and it got me thru the next 3 days in Canada without leaking gas. Now I am trying to find out why it is sliding up so I can fix the problem. Any ideas?? Model E150FPLEEA