I fired my boat up this weekend, and could not get it to idle. I tried two carbs the 644 and 813. I found a bad diaphram in the water pump would that cause a no idle situation, I have a enforcer team pro. the pulse port is in the intake manifold for the water pump and it has a wet tuned exhaust. I ordered a new diaphram set but have not received it yet to try. also is there any benefit on running a 257 carb, versus 813 or 644, thanks Dennis

bad diaphram will suck air. carbs are pretty much the same

A quick & easy test would be to remove the water pump pulse line & try them again .Check your fuel line for Pin holes or bubble's too while you at it as ive had problems due to tiny holes in the line before leaking air:dash: it wont idle but will still run .Good luck ..Wayne

As Wayne suggested, remove water pump and test again...don't forget to plug the port hole on the carburetor iso block. An air leak there will cause stuff like you are describing.