Won't stay running, Johnson 10HP 1954

[DallasJeff]

Recently acquired a '54 Johnson 10HP outboard from Craigslist.

Got on the water last night and the motor started up on the second pull. It ran fine for about 2 minutes but when I turned the throttle from "start" to "shift" It died. Started back up and ran about 2 minutes with throttle in "start" position. Then it died and would not restart.

Vented the tank and fished for about an hour and tried the Johnson again and it started on the second pull. Ran for about a minute or two then died and would not restart. After thirty minutes tried it again and it started on first pull. Again ran for one minute and died. Would not restart.

Reading around this forum looks like the next thing to do is get a pressure gauge and check cylinder compression and spark (should be > 100 psi, right?). I'm also considering cleaning and rebuilding the carb including new float and needle. The coils are supposedly good, replaced by the previous owner. This is the first outboard I've ever owned or operated so working on it is new territory. I also acquired a repair manual published by Clymer.

Any suggestions or help with diagnostics is appreciated. I'll keep a running log of my diagnostic testing and repairs in this thread.

 

[DallasJeff]

Re: Won't stay running, Johnson 10HP 1954

http://www.youtube.com/watch?v=-37LgmUoJ1c

Idled it down at about 30 second mark of the video and again at about 40 second mark but it almost died so I throttled it back up. Eventually it died and wouldn't restart. Never tried to put it in gear.

[youtube]37LgmUoJ1c[/youtube]

 

[The-Machinist]

Re: Won't stay running, Johnson 10HP 1954

Does your motor still have the 2 line pressure tank? If so, thats where I would focus my search, at first. Those two line tanks have to be in a pretty good working order to work properly. Check for leaks around the top of the tank, and inspect all lines. Also, make sure your tank still has the gasket where the fuel cap screws on. If the tank cant hold pressure, it cant force fuel to the motor.

 

[DallasJeff]

Re: Won't stay running, Johnson 10HP 1954

When I bought this motor it had a hokey homemade pressure tank. I replaced it with a used tank in refurbed condition from Craigslist. I just bought new gas lines yesterday but the quick-connect had a leak. The local OMC repairman sold me a new o-ring but it turned out to be the wrong part. So I took the quick-connects off (temporarily) and ran the new gas/air lines directly. The pump on the tank seems to work, after two or three pumps gets very firm and when I loosen the gas cap there is a lot of pressure that vents. After the motor died I loosened the gas cap and there was a lot of pressure that hissed out. There is a gasket inside the cap that looks in good condition. As far as I can tell the gas can and pump are working correctly. I have also confirmed that there is no gas leaking anywhere around the tank or lines and connections.

 

[DallasJeff]

Re: Won't stay running, Johnson 10HP 1954

Tonight I put the motor over a large trash can filled with water and could not get it to start at all. Pulled the plugs and they look pretty good to me. They are Champion J-4J. Here they are:

Tested for spark and got a spark on both. Well, the first charge went into my fingers. But after that both tested good. I even had some combustion, a little ball of fire, come out of one of the spark plug holes when plug sparked near it.

I can look more into the fuel supply problem if someone could tell me what to look for. The tank definitely has pressure. the little glass bowl under the carb is full of gas with a slight amount of sediment settled in the bottom. The pump really gets firm to the point that you can't compress it anymore.

 

[jbjennings]

Re: Won't stay running, Johnson 10HP 1954

You're not going to get over 100lbs of compression on that 10. Mine all have around 85 and run great. I doubt they had over 100 brand new. I'd feel pretty good if they had 80 or above. It's hard to tell what your problem is. If you haven't pulled the flywheel yet, do it. you need to clean and set the points and look for crappy coils. I had a 2.5 hp johnson that had a bad condenser that would quit working after the motor warmed up just a little. But I doubt that's the problem. Sounds more like a sticky float needle or bad the cork float may be gaslogged. If you haven't cleaned the carb. you might as well get it over with---it's very easy. Between the two, you'll find your problem. You should replace your fuel hoses if they're original, too.
Good luck,
JBJ

 

[Basher]

Re: Won't stay running, Johnson 10HP 1954

Dallas

I have a 1956 Johnson FD-10 15 HP. I have rebuilt the electrical and fuel delivery system (tank and carb). Have you tried totally closing your high and low speed adjustment screws and then backing them out 1 1/2 turns. I had similar problems with my motor and this seemed to solve mine.

You may need to fine tune the adjustment from this point but it should get you running.


Basher

 

[DallasJeff]

Re: Won't stay running, Johnson 10HP 1954

Thanks for the replies, the carb work will begin tomorrow. I have a feeling some small debris has gone into the carb. The old o-ring on the fuel line was cracking and going into pieces. And the old fuel line had a filter installed in-line, which I removed and a bunch of crud come out. I installed new fuel lines but there's the possibility some small pieces of the old o-ring or crud from the old line got in and is clogging a jet.

I haven't touched the carb adjustment screws yet. I have tried all sorts of settings on the high speed and low speed dials for lean or rich mixture.

 

[DallasJeff]

Re: Won't stay running, Johnson 10HP 1954

Got it running! It was the filter stone causing gas starvation.

Took the carb apart yesterday and cleaned it. Found a carb kit today and put it back together this evening. Still wouldn't start and it was hard to pump gas into the filter bowl under the carb. Took the filter stone out and put back only the glass bowl without filter and it filled easily with just a little pressure. Motor started on the second pull. Apparently the filter stone is too clogged to allow fuel to flow easily.

Its still running rough at low idle but that should be a simple matter of getting the needles adjusted properly.

Also tested the compression on both cylinders: 88 psi on top and 90 psi on bottom.

Also tested the coils by placeing the plugs 1/2 inch away from ground. Pulled the cord and got an arc across the 1/2 inch gap. Couldn't get an arc much further than that but that seemed more than adequate.

man, I sure learned a lot doing this overhaul. Thanks everyone for your help. I may need some advice later on setting the slow and fast needles.

these pics are before cleaning. I think I'll have that cold beer now!

 

[jbjennings]

Re: Won't stay running, Johnson 10HP 1954

88 and 90 is really good compression to me on that 10. I think you're going to like that motor. The only thing I might suggest just by looking at the pics is resealing the float. I hear model airplane dope works good but have never tried it. Post a pic of it when you get it running just like you want it. I love the looks of the '54 10 hp.
Glad you solved the problem--I would have never guessed that filter would have been the problem.
Later,
JBJ