1988 Johnson 30 HP Fuel Pump ?

[wut4dude]

My always trustworthy '88 Johnson 30 outboard began having fuel issues shortly after installing a fuel/water separator. After some simple troubleshooting, I found that my fuel pump wasn't delivering the fuel to my carb. I have fuel supply at the inlet, but the outlet to the carb is bone dry. So, my local marine parts supplier didn't have the correct fuel pump in stock, so I ordered one and should have it in a couple of days. I decided to remove the existing fuel pump...I removed the two hoses, inlet and outlet and the two screws which secure it to the motor. I noticed the mounting gasket had a tear in it....ok, here's my question. This gasket has 3 holes, 2 are for the mounting screws and the middle one, I assume is to drive the pump. The associated opening in the side of the engine block has threads, but there's nothing pertruding from this opening. Am I missing something? What actually drives the fuel pump?

 

[Crosbyman]

a tear in the base gasket is not good but how big is i? t ...enough the cause an air leak preventing engine air pulses from reaching the pump ?

​ if so just replace it (cheap) but....



the 3 hole base gasket is just that a spacer to seal the pump on the block the middle hole lets a air pulse flex the internal diaphragm which sucks gas by flexing
back and forth... check valves allows the fuel to be pushed out to the carb tanks the piston blow back ar pressure pushing on the pump,s diaphragm.


you ahve no missing part in that middle hole... it is the air channel

​ you may have a busted diaphragm or just dirt etc... of the pump's top cover mesh filter. it may may be totally filty with crud.

take it off and clean the wire mesh screen ...at least and retry

​you can try a temporary diaphragm by cutting one out of a nitrile work glove. just for a test ... then go buy a good one at the dealer

 

[oldboat1]

Yeah, pretty easy rebuild or just a mounting gasket. Maybe your source would exchange for a kit.

 

[wut4dude]

...thanks Crosbyman, I figured it worked off of the air pulses from the engine, but when I saw the threads, it made me think. I know I could probably just gotten away with replacing the gasket, or buying a rebuild kit, I decided to just order a new pump. This particular pump has a plastic nipple for the outlet hose and it had a small crack in it...so I decided the new pump was the way to go. Thanks again for the advice.

 

[oldboat1]

(sounds like the right choice -- have the old one for parts.)