7.5 fuel pump

[guzzijohn]

I have a'71 7.5 merc which had a cracked plastic pump cover. I got a cast replacement plus gaskets and it is assembled but have question. The plastic one has a port over the smaller section of the diaphragm the cast one doesn't. I'm thinking the cover was meant for a pump that had the port in the center section. I'll drill a hole if needs be but would like to know if it is necessary. After seeing a drawing of the pump in Clymer book the port would be useless except to buffer the pulse going to the carb.

[boats.net]

Fuel pump needs three ports, inlet, outlet and pulse port going to intake side of engine block. If the old pump had a hole going all the way through to pulse diaphragm in pump then new pump would also need a hole.

[guzzijohn]

There are 3 ports. The hole in the plastic part was just open. The threaded port for pulse hose is on the end of the plastic part instead of on the front like the cast one.

[boats.net]

Ok it should work ok.