Evinrude 65hp Commercial Fuel Pump.

[Small Peru]

Hi,
I have a 1988 Evinrude 65hp Commercial outboard engine and I want to change the fuel assembly (Part #398399) because the plastic part of the pump broke off the original.

The problem I'm having is finding a new pump that is identical to the one I have.
I purchased a new pump (jobber part #438557 or similar) but the back side of the pump has a hole in the middle (between the two screws that hold the pump to the engine) that is open where as the original the middle hole is not open. (See images)

I was wondering if I could install the jobber, with open hole, and not have it impact the performance of the pump since there is not hole in the engine at that location which means that hole would be either be, sucking or pushing, outside air. (I'm not quite sure what the hole is used for)

Thanks!

 

[racerone]

Are you sure that hole goes through to the diaphragm?-----Put a few drops of oil in the hole.-----See if it drains away.

 

[Small Peru]

Are you sure that hole goes through to the diaphragm?-----Put a few drops of oil in the hole.-----See if it drains away.

Yes it does.
If you look carefully at the Internal part, next to the hole there's another, less obvious hole, that connects to a hose fitting that connects to the crankcase, to provide a vacuum to make the diaphragm pulsate, If I understand correctly.

 

[racerone]

The pump operates with crankcase PRESSURE.----It will not work if that hole goes to the diaphragm.----Unless a gasket is used.----I see one hole in the second picture.----That hole goes to the hose fitting.

 

[Small Peru]

The pump operates with crankcase PRESSURE.----It will not work if that hole goes to the diaphragm.----Unless a gasket is used.----I see one hole in the second picture.----That hole goes to the hose fitting.

You're correct, however the 2nd picture is original part and not the jobber which I want to install.
The 1st and 3rd pictures are the jobber.

What you are seeing here is the diaphragm with a gasket underneath from the jobber part (2 holes).

Currently I used the base part of the old/original pump (2nd picture above (1 hole)) and added the other parts from the jobber to make it work, since one of the original parts broke, but the bulb on the hose from the fuel tank doesn't stay hard, which is why I wanted to swap it with the jobber.

 

[racerone]

When a motor is running the bulb goes soft.----It does not need to stay hard.

 

[Small Peru]

When a motor is running the bulb goes soft.----It does not need to stay hard.

Thanks for the info racerone, much appreciated!