2000 225 vmax dies while driving

[Docbarnvet]

Engine started dieing on me while drving down the lake. Took it to a mechanic and they replaced the diaphrams in the fuel pumps and replaced the sprak plugs. Ran much better but wold die again at 60 mph, then before the boat stopped started back up on its own. When I try to pump the gas blub it never gets hard. What else could be the problem?

[boats.net]

If fuel injected model then have fuel pressure test run on it. Check for loose fuel hoses or a restriction in fuel hoses or fuel pickup in gas tank.