18 Horsepower Johnson Troubles

[Thompy_04]

Just picked up a 1960 Johnson Seahorse 18 Horsepower outboard. Started when I bought it and didn't think any troubles were going to follow. I was wrong. Took it to the local marina to test run it and it was a dog from the start. Did a compression test and its about 100 in each cyl. Did a spark test good hot spark with new plugs. Here's the deal. Primed the ball and is firm after 5 pumps yet leaks just a little gas out of the carb, maybe a gasket is bad. You can here a leak sound like a spray is coming out somewhere. I took the fuel hose off and when you pump the ball a spray comes of of the connector, could this also be the prob? I can get it to run for about 8 seconds, while sputtering it will quit. Since I am getting spark it has to be a fuel delivery problem. Eventually the prime is lost and the process has to start all over again. I really don't know the carb settings so I made due, and you really have to richen the mixture to get it to start. Maybe the carb needs to be cleaned, I really would say thats it. Or even a new fuel pump kit will fix the prob but any info will help. Can anyone help with suggestions? New water pump impeller put in this year and pumped good water when I had it running for the 8 seconds, but I'm really wanting to get out and run this motor. Any input will help. Also can I still get parts (carb kit, fuel pump repair kit) at my local Johnson dealer or do I have to order from the internet?

 

[petrolhead]

Re: 18 Horsepower Johnson Troubles

You can get all the parts you need from your Johnson dealer, problem is they may not have parts catalogues going that far back, mine only has them back to 1968 which is no good for my 1958 18hp!<br />Either get a parts catalogue for your motor so you can quote the correct numbers to your dealer, or get someone to tell you the numbers you need, your dealer should then have no problems getting the parts. Alternatively there are lots of online sources which may be cheaper.<br />It sounds like you need a carb kit for starters, and that leaky connector doesn't sound good either, not sure about fuel pumps as mine has the older pressurised tank and no pump, but I'm sure rebuild kits are available for that too.

 

[BoatBuoy]

Re: 18 Horsepower Johnson Troubles

Sounds like you may need a new float in the carb float bowl. When you get a carb kit, be sure and get one that has a new float. In some cases, the kits come with or without floats.

 

[petrolhead]

Re: 18 Horsepower Johnson Troubles

Sierra kits come without floats, apparently the genuine OMC kits include them.

 

[cajun555]

Re: 18 Horsepower Johnson Troubles

Yes the kits from OMC come with a float. Walked into my OMC dealer and he had the kit on the shelf for '56' 30 hp. I've found out a parts house and not a boat dealer/ with a parts counter are more helpful. The kit, 20 bucks and some change.

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Also the motor tends to backfire when you try to start it. Any suggestions on whats going on there? Seemed to be flooded somewhat, maybe because of the slow speed mixture being set so high? Trying to get this one sorted out and any info would help, thanks.

 

[cajun555]

Re: 18 Horsepower Johnson Troubles

Thompy, check your points, gapped at.20, plugs gapped at .30, check coils for cracks, check plug wires, make sure flywheel key is good. As far as idle mixture adjustment turn CW till lightly seated then CCW 1.5 turns. That you should get you in the ballpark. Then CW till motor runs rough then back out about .25 turn. The best thing you can do is get a manual, that way were not guessing. You can get a manual off this site. <br /><br /> Good luck<br /><br /> Forgot to add, When you put flywheel nut back on to make sure it is down good and tight. If that suckerbill backfires it can damage the flywheel. 480-540 in. pounds.

 

[reload]

Re: 18 Horsepower Johnson Troubles

If I am understanding this right. You say when you pump the bulb you get gas spraying out of the connector before it gets to the engine. Even with the fuel line disconnected from the motor. If this is correct you will have to repair this first. The fuel pump will be sucking air instead of fuel through the hole that leaks under pressure of the bulb. Also it sound like you have a timing issue that will be corrected as stated by the procedure cajun555<br /><br />Paul

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Ok went out the morning to see what was goin on with the ole girl.... She had no spark in the top cylinder. Did a spark check with both plugs just to see if one was bad, sure enough no spark. Bottom cylinder is the only thing keeping her alive. It'll run real rough for about a minute now, pump good water and I can even give it some throttle and it will rev real low then die. Cleaned the carb just to make sure earlier to no prevail. As with the spark, I really don't know much about the electrics with an outboard. Just graduated high school but work on small engines alot, just not the electrical part of them. Where do I start as far as checking the electrics (points, condensors, coils, magnetos)? Just ordered a manual by the way. Thanks guys

 

[petrolhead]

Re: 18 Horsepower Johnson Troubles

Check the coils for cracks, points for pitting and/or dirt, HT leads for cracks etc... <br />Personally I'd just assume all the electrics are shot and replace the lot, coils, points, condensors, HT leads and plugs. It will cost very little to do this and will eliminate many sources of trouble.<br />I'd also get the carb kit and rebuild that, another very easy and cheap job.<br />Check the O-ring seal in the fuel line connector, it may be perished, chances are it's never been replaced and a new one costs about 50c.

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

As far as checking all these electrical components, how abouts to I do this? Common sense tells me I need to take the flywheel off to get to all these parts and reading forums on this great site suggests using a harmonic puller from an automotive store. Is this the way to go, and when I get the flywheel off what can I expect to see inside? Just trying to learn as much as possible untill the manual gets here because I'm dying to get her out on her madien voyage. I understand the coil concept, but as far as the poins condensors and HT leads I have no clue. Please elaborate on these parts. Thanks

 

[petrolhead]

Re: 18 Horsepower Johnson Troubles

A visual inspection of the parts should tell you if they are OK or suspect. The coils will most likely have cracked cases if they are old, pitting of the points will be obvious when you look at the contact faces, the only thing you can't check visually is the condensors. But as I suggested you'd be best replacing all these components anyway, coils are less than $20 each, and a kit containing two sets of points and condensors is around $15.<br />Yes you need to remove the flywheel and you need a harmonic puller to do this, you may be able to hire one from your local outboard repair place, or even take the motor down there and ask them to do it for you. When it's off you'll see all the components mentioned above fixed to a metal plate, this plate rotates when you open or close the throttle, this advances or retards the spark, when you see it this will all become obvious.<br />You have to remove the plate to work on it, a simple job requiring no special tools, just a screwdriver. Once off it's just a case of unscrewing the old components and replacing them, takes a half hour max, replace the plate, gap the points (you need a screwdriver and feeler gauge), replace the flywheel (torque wrench required) and that's it!<br />You'll need to check, and probably re-syncronise the fuel and spark systems so that the carb starts to open at the correct time, exactly how this is done will be explained in your manual, which one did you order BTW?

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

I ordered the Seloc manual and should be expecting it soon. I'll look through it and get myself aquainted with all the parts before I go breaking them down. All of this seems simple enough if all the parts are right there in front of me and pretty obvious to the naked eye. Checking and re-syncronising the fuel and spark system is getting me though. As far as the carb, I can set the high and low speed screw correctly, also seeing how there is only one carb there is no need to sync two or more of them. But syncronising the spark system? Whats this you are speaking of? And how do you set the points? Is it similar to gapping a plug bending and checking, almost like trial and error? Or is there just one spot that needs to be set?

 

[petrolhead]

Re: 18 Horsepower Johnson Troubles

Setting the points is just like setting a plug gap, except instead of bending them there's an eccentric adjuster which you turn with a screwdriver.<br />Synchronising sounds like it may be complicated but isn't! The carb is operated by an arm that picks up on a cam, which is mounted on the moving armature plate (which the coils and points are mounted on). As the plate rotates and the spark is advanced, the arm picks up on the cam and starts to open the carb flap, it's important that the carb starts to open at the correct time, otherwise the fuel and spark will be out of sync. This is achieved simply by adjusting the cam in or out and tightening the mounting bolts.

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

I'm sure that the Seloc manual will explain how to do this, hopefully. Just ordered new points, condensors, 2 coils, and a carb rebuild kit. Hopefully this will totally fix the prob becuase the largemouth on the Ohio River are calling my name! I'll keep you guys up to date on the project, and will refer to you guys if I have any trouble. I appricate all your responses, this truly is a money, time, and headache saving site!

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Well before I get any further on the project here, I was just wondering if there is someway you guys could help me with the electric start. Its not necessary but since I'm on the electric subject I was just courious. When I bought the motor the guy didn't know it had an electric start, yet it does. There is a terminal with 2 large prongs, and in between them is 3 small prongs. I hit the 2 large prongs with a wire to my batter and she turned over. I was just seeing if the started actually worked. Can I buy a harness to put on these prongs and run a ignition switch to the harness to get an electric start motor? Or can I rig one up and use some kind of automotive ignition switch? Any suggestions

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Took the flywheel off today, and set the points to no prevail. Still no spark, expecting the parts in a few days and will keep you up to date on the project. Till then does anyone have any suggestions on the electric start? I have the basic info in the post above. Can you guys help me out again?

 

[Paul Moir]

Re: 18 Horsepower Johnson Troubles

Try Twin City Outboards for the harness.<br /><br />You want to rig up the starter yourself, start by buying the proper marine outboard starter solenoid. It's wired a little different then a car one with it's 'S' and 'I' terminals, and is explosion proof. Iboats sells them if you need one. Something like Arco SW622 will work nicely.<br /><br />For details on the wiring, have a look at the diagram in FAQ posted by Xcuseme:<br />FAQ<br /><br />I'm not sure if your outboard has a saftey cutout switch on it. If it does, you connect into it via the base of the vaccum cutout switch. That's the thing connected to the manifold by a hose.<br /><br />Hope this helps!

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Well now I have a new prob.... Yes a new problem. I can't get the flywheel off again. It won't budge and I don't want to force it off, and risk breaking anything. Any tricks to getting these things off? I have a harmonic balancer puller, to pull it off from the center. But when I put tension on it, like I said it won't budge?

 

[petrolhead]

Re: 18 Horsepower Johnson Troubles

Try some penetrating oil, WD 40, tighten up the puller and if it doesn't release leave it under tension for a while. My experience with pulling flywheels etc... is that they often pop off of their own accord while your back is turned!<br />Otherwise you might try a few light taps with a soft hammer while it's under tension.