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1973 Johnson 25 hp starts but won't stay running

Yes. If the tank is the original OMC steel can with the coupling not only at the motor but a second coupling down on the tank there could be a defective vent causing pressure to build up if the sun hits the fuel tank. As you can notice there are two stainless pins that are depressed when you clip the coupling to the tank. One of the pins opens a little vent right next to it and the other pin opens up the fuel flow to allow passage into the line. If these are operating properly then there is no need to crack open the fuel cap. If the tank/can is sitting out in the sun and the fuel line has been disconnected at the fuel tank then it will build pressure because the pins are not depressed. It is a beautiful system and trouble-free for many many years up until ethanol has started to damage the o-rings where those little pins move in and out. There are kits available to replace those old rings and the seat on the pins in order to recondition the coupling.
 
timguy said:
Yes. If the tank is the original OMC steel can with the coupling not only at the motor but a second coupling down on the tank there could be a defective vent causing pressure to build up if the sun hits the fuel tank. As you can notice there are two stainless pins that are depressed when you clip the coupling to the tank. One of the pins opens a little vent right next to it and the other pin opens up the fuel flow to allow passage into the line. If these are operating properly then there is no need to crack open the fuel cap. If the tank/can is sitting out in the sun and the fuel line has been disconnected at the fuel tank then it will build pressure because the pins are not depressed. It is a beautiful system and trouble-free for many many years up until ethanol has started to damage the o-rings where those little pins move in and out. There are kits available to replace those old rings and the seat on the pins in order to recondition the coupling.
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Thanks Tim! Everything is original on this motor, except the paint. Because of where we live, I must store my boat at a storage lot. It is kind of in the shade, plus it always as a rain cover on it. Do you happen to know a number of the kit to replace the rings. If I call Tim's Outboard, would they know what I am. talking about?

I had a friend over last Friday and we had to things I wanted to get done. On was replacing the gaskets between the motor and the lover shell and the shell and the lower unit. We got all the bolts and nuts off but could not get the motor loose from the shell. I then remembered why. About 15 years ago, I had to replace the crankshaft. I am sure that when we put it back together we used some type of gasket seal on those gaskets and they were not going to let go. It did assure me that they were not leaking anything as all was clean in that area. I am going with your suggestion and get the gas tank repair kit.

The second issue I wanted to correct was replacing the missing piece that sits on top of the flywheel that catches the recoil levers to start the motor by hand. I think it was the same event (replacing the crankshaft) where I forgot to put that piece back on during reassembly. To make matters worse, it has been lost over time. I ordered a replacement from Tim's Outboard. He had trouble finding one but did find one at a premium $54.00 price! Anyway, we took the recoil off and discovered some damage on the under side. I am going to attempt to add a couple of photos. The pieces of metal that hold the pieces that spring out during operation were worn down on one end only. Even the heads of the screws were worn off. You can see a shiny ring on the top of the flywheel where it must have been rubbing. It was very slight as I do not recall hearing any scraping noise. The result it the pieces that are supposed to pop out during the recoil operation do not. In your stash, might you have parts that would work for this? I will be more than happy to pay for them. Basically I need the metal covers and the inside pieces. Again, this is for a 1960 40 hp Johnson.

Sorry this got long, but as you know, when you try to fix one thing, something else always shows up.
 

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your location?--Are the 3 little springs in good shape? Is The spring on the hub assembled correctly?
 
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The 3 little springs are there but not functioning. I can move the paws (or whatever they are called) in and out, but they do not move freely like they should. I think they are binding because the plate that holds them on is damaged. As the picture shows, the plate and the screw that holds it on was ground off on one end on each of the three plates. I am going to need to cut a slot in each of the screws to get them out. I think this was caused by me forgetting to put a spacer between the recoil unit and the motor mount. It was just barely touching the flywheel but enough to do the damage. I am in Colorado.
 
BruceWayne426 said:
Thanks Tim for your response. If you search my name on the forum you will find another thread about my motor. RacerOne took a real interest because he had heard about military motors but had not actually seen one. He asked for several pictures, which I supplied. In the end, he discovered that even though my motor is titled as a 1982 OMC Military motor, the parts were made (and lost in a warehouse) in the early 1960's. When they were discovered, OMC knew that they could not sell them as a new Johnson of Evinrude 40 hp in 1982, so they assembled them with a few changes and sold them to the military. So you are correct, it is actually a 1960 or so Johnson. I have the gaskets so I am going to go ahead and replace them. I will pull the motor first and see if that gives me access to both gaskets. You comment about "what seems to be a leak" makes a lot of sense. I always have to tilt the motor to get it out of the water and up the ramp where I fish and then leave it tilted when I put the transom saver on, so it is always tilted out of the water. Would it help if I disconnected the fuel line each time and maybe open the cap on the gas can to release the pressure? Good call! Thanks so much.
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Hey Tim...It has been a few months since I las reached out to you for your good advice. I followed your advice and unhooked the gas line at the dock to run a little gas out of the carb. That cleared up the dripping. The motor runs great, starts great, etc. But a new issue popped up a few weeks ago. I discovered a leak in the gas line from the tank to the fuel pump. Since I had not ever replaced any gas lines, I replaced all three - tank to pump, pump to the plastic sediment bowl (I think that is what it is) and sediment bowl to carb. It was running perfectly before and now I cannot get it to start at all. All lines are new and clear. I bought metal clamps to tightly secure the lines. My first thought was bad fuel pump. I disassembled it - this diaphragm was soft and pliable, no tears, filter is clear. If I take the hose off the outlet side of the pump, and crank the motor, or squeeze the bulb, gas does not come out of the pump. I took the carb apart and made sure there were no blockages there. Do I need to prime the lines? If I squirt a little gas in the carb it fires right up but will not keep running. I am stumped. The motor was running great when I came out of the water, the only thing I did was change the gas lines and now it will not start. I appreciate any ideas you might have. Thanks!
 
Thanks for your reply racerone. As a refresher, the is the 1982 OMC Military that you researched and identified as a 1965 Johnson. I do have a full military operations manual.
The screen shot is from the military manual. I added two circled text boxes to indicate how I have the gas lines hooked up. The left circle indicates the line coming from the gas tank to the inlet on the bottom of the fuel pump. The right circle shows the line coming out of the secondary fuel filter (which I labeled a sediment bowl in my earlier post) and going to the carb. I am almost certain that is the way they were hooked up before as I only replaced one line at a time but at this point, I am at wits end and not sure of anything.

As always - I appreciate your assistance.
 

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On a normal civilian engine, fuel from tank goes into the black filter cap #5 and leaves pump heading to the carburetor thru the bottom of pump thru hose #11.
So that being said, I believe your 2 circled hoses labeled "from gas tank" & " to carb" are labeled backwards.
As currently labeled the pump is trying to suck fuel from the carb & pump it to the tank.
 
With a big piece of humble pie in front of me, I will close this thread with the admission that I had the hoses hooked up backwards. As always, I appreciate racerone, who is always quick to help and to Droid for chiming in as well. To add insult to injury, when my wife heard the motor fire up, she came running out to the garage to see what I had done to fix the issue. While explaining to her how the hoses are supposed to be hooked up in contrast to what I had done, for the first time I noticed "IN" embossed on the inlet of the fuel pump fuel filter. Thanks again for this forum and to all who contribute. Going fishing in the morning!
 
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