Re: 1975 Johnson 25HP won't start
This post caught my eye as I recently re-installed my 25HP Johnson after two years storage.
Does it run with the choke half closed? Then it could easily be the fuel pump. I think however you have maybe multiple issues and should adress them all. It took me a good hour in work and two days searching parts, but well worth the effort.
On mine during storage some water condensed (is that how you say it?) on the tiny shutter valves in the fuel pump. Seloc says fuel pumps can't be serviced but you can definately take them apart completely to check. These shutter valves are very thin sheets of spring metal allowing the fuel to flow only in one direction. One drop of water caused one to rust and a tiny hole appeared. These holes get bigger quite fast so it's quite possible that the engine ran just after storage (and sale) and developed a hole afterwards. Also I notices that all fuel lines get hard and although they don't leak there's a chance that they suck in air somewhere along the way. Just a tiny air leak can affect the fuel flow quite a bit I noticed. Another part prown to rust is the shutoff valve (or actually the "spring", don't know the exact name) that ataches the fuel shutoff to the carb float. It is included in the carb overhaul kit. I would replace all fuel lines, use new clamps, check the seals between fuel pump and the hole in the engine providing the vacuum. Check the diaphragm in the fuel pump and the shutter valves and also see if the seal from where you connect the fuel line to the pump is still good. Then open up the carburator, check the float and just use compressed air to blow out any rust particles and other debris that also migt be there since the whole system has been idle for two years. Check carb float distance and see of the spring is still good. If fuel comes out of the carb when squeezing the ball very hard I would suspect also stuck float or that spring being faulty..
You have a spark so I wouldn't suspect kill switch but make sure they can't short anywhere. I once had weak spark because of water getting into the kill switch circuit.
It's not very difficult to do these things. Just take carb and fuel pump off and sit on the kitchen table for an hour or so
Enjoy!
This post caught my eye as I recently re-installed my 25HP Johnson after two years storage.
Does it run with the choke half closed? Then it could easily be the fuel pump. I think however you have maybe multiple issues and should adress them all. It took me a good hour in work and two days searching parts, but well worth the effort.
On mine during storage some water condensed (is that how you say it?) on the tiny shutter valves in the fuel pump. Seloc says fuel pumps can't be serviced but you can definately take them apart completely to check. These shutter valves are very thin sheets of spring metal allowing the fuel to flow only in one direction. One drop of water caused one to rust and a tiny hole appeared. These holes get bigger quite fast so it's quite possible that the engine ran just after storage (and sale) and developed a hole afterwards. Also I notices that all fuel lines get hard and although they don't leak there's a chance that they suck in air somewhere along the way. Just a tiny air leak can affect the fuel flow quite a bit I noticed. Another part prown to rust is the shutoff valve (or actually the "spring", don't know the exact name) that ataches the fuel shutoff to the carb float. It is included in the carb overhaul kit. I would replace all fuel lines, use new clamps, check the seals between fuel pump and the hole in the engine providing the vacuum. Check the diaphragm in the fuel pump and the shutter valves and also see if the seal from where you connect the fuel line to the pump is still good. Then open up the carburator, check the float and just use compressed air to blow out any rust particles and other debris that also migt be there since the whole system has been idle for two years. Check carb float distance and see of the spring is still good. If fuel comes out of the carb when squeezing the ball very hard I would suspect also stuck float or that spring being faulty..
You have a spark so I wouldn't suspect kill switch but make sure they can't short anywhere. I once had weak spark because of water getting into the kill switch circuit.
It's not very difficult to do these things. Just take carb and fuel pump off and sit on the kitchen table for an hour or so
Enjoy!
