71 Johnson 25 fuel hose??question

[twocyclemania]

Just picked up a 1971 Johnson 25. Managed to get her to fire up today after cleaning the points. She pumps and runs well but stalls out after about 30 seconds. There is a black hard small diameter hose that extends from (I believe) the bottom of the carburetor and has a metal nipple fitting on the end. Gas is spraying out of this hose when the motor runs. I believe it's supposed to connect to another nipple fitting a few inches from where this one terminates (missing a rubber connector??). This fitting is on one of the two side plates above the fuel pump. I'm used to older motors and don't have anything like this on the cousin 18's I have. What is it's purpose? Is it supposed to connect to that side plate? Why is gas shooting from it? thanks for any help!

 

[nwcove]

Re: 71 Johnson 25 fuel hose??question

pics would help, but could it be the oil line to the top of the engine?

 

[kfa4303]

Re: 71 Johnson 25 fuel hose??question

Hi twocyclemania. Can you tell us what hose you mean from the diagram in the link below? You should really only have 2 fuel lines. One coming into the motor's fuel pump from the tank and one line coming out of the pump and into the carb. The pump itself is mounted on the engine block. If you're talking about a thin hose that runs from the bottom of the power head to the top, but is not connected to the fuel pump, then I think nwcove is right, and you're talking about the oil line. It runs fuel/oil from the bottom of the powerhead to to the top in order to keep the upper bearing lubricated.

http://www.marineengine.com/parts/j...5R71S&manufacturer=Johnson&section=Carburetor

 

[twocyclemania]

Re: 71 Johnson 25 fuel hose??question

It is a a thin hose (rigid). It must be the oil line. Does it indeed connect to the upper side plate (which right now is open)? Does it use a rubber hose connector? Why does this motor have this system when all of my other older motors do not (ie need to lubricate the upper bearing)? Will this being unconnected affect the running of the motor as I experience it stalling out today? By-the-way- thanks for the responses and help.

 

[nwcove]

Re: 71 Johnson 25 fuel hose??question

the hose will get rigid because of age. my mid 50's smaller motors have that line. dont run it until you are sure of the purpose or you may cause damage that will get costly.

 

[kfa4303]

Re: 71 Johnson 25 fuel hose??question

Yeah, it sounds like you're describing the oil line. They do tend to be sort of thin and rigid. Most vintage motors have them. I'm not sure about modern, 4 stroke motors. It should definitely be connected and may well have caused the problems you were having by creating an air leak. Here's another thread right here in the forums of a guy with a very similar issue.

http://forums.iboats.com/showthread.php?t=532398

 

[twocyclemania]

Re: 71 Johnson 25 fuel hose??question

Just for clarification: This hose is rigid by design. I believe it's what has been described - an oil line. I'm going to add a connector to the side plate and see how it goes. thanks

 

[F_R]

Re: 71 Johnson 25 fuel hose??question

C'mon, everybody. I think he is describing the crankcase drain hose. It runs from the intake manifold, below the carburetor, to the upper bypass cover. There is another hose between the lower and upper main bearings, to supply oil to the upper bearing.

Now about that drain hose: At slow speeds, fuel tends to settle in the crankcase (sort of like rain). In older motors, that fuel was simply routed internally and dumped in the exhaust---and ultimately in the lake. In the interest of environmental concerns, starting in the early 1970's, the drainage was routed to the bypass cover, where it then goes into the upper cylinder and (hopefully) burns. THAT is the hose, and its purpose. It is a special hose, larger internal diameter at the front end, and smaller at the bypass cover end.

 

[twocyclemania]

Re: 71 Johnson 25 fuel hose??question

F_R: You hit the nail on the head. Right now there's a hose missing that connects it to the upper cylinder. When running; its shooting gas out of the end. Should there be much of a volume of gas coming through it like I'm experiencing? Also, since it's disconnected would that affect the running of the motor? When I add a hose connection should the motor run better or does that have nothing to do with the overall running? thanks!