1972 Johnson 100HP... NO START :(

[SuzukiChopper]

So I just finished completely rebuilding my boat. Decided tomorrow would be a great day to take it out and test it (been raining and windy for the last few weeks). Put the muffs on, turned on the water, primed, turned key (and choked) and it wouldn't start. Tried and tried and tried and wouldn't start. So I pulled each one of the plugs (one at a time), they were wet with gas (oops maybe flooded?). But I checked the spark on each one anyways, perfect, nice and blue. Cleaned and dried the plugs, put em back in just to hear the motor TRY and start. No go. Made sure the fuel was flowing, spark was there, everything, didn't even TRY and start. Anyone have any ideas what I can try? I'm going to go buy new plugs tomorrow and try that but I'd like some backup for this old beast incase it decides it doesn't want to play nice.

 

[Saskatoon2005]

Re: 1972 Johnson 100HP... NO START

Have you rebuilt the carburetor? I had trouble starting my 1961 Johnson, and once I rebuilt the carburetor, it started right away.

 

[SuzukiChopper]

Re: 1972 Johnson 100HP... NO START

I'm thinking I may have to do that Is it tough getting the carbs off? And once I do are there any gaskets I have to worry about?

 

[McGR]

Re: 1972 Johnson 100HP... NO START

Spray a little fuel down the carbs... If it kicks, then you have fuel issues. If you are unsure of the condition of the carbs, it's probably best to rebuild. They aren't hard to take off. All the parts and gaskets you need will come with the rebuild kits.

 

[papasage]

Re: 1972 Johnson 100HP... NO START

if plugs are wet it is gitting fuel . try a new set of plugs. try the gapped type . they dont fowl like the surface plug. L77JC4 is what i run the book showes a L77V. this plug doesent gap and will foul easley . will give a better performabnce but it want idle as long and if running rich it wil foul

 

[SuzukiChopper]

Re: 1972 Johnson 100HP... NO START

Well it does seem like it's running rich. The plugs were pretty black. Maybe the previous owner was running to high of a fuel/oil mixture? What should I be running with this motor? 50:1 or 14:1? After looking at the weather forcast I'm really hoping I can get out today, ran ALLLL weekend AGAIN <br /><br />I guess if I can't get it to go with the new plugs and I find out that spraying fuel down the carbs helps, then I'll be going to get the carb rebuild kit. Thanks for the help, here goes nothing!

 

[JB]

Re: 1972 Johnson 100HP... NO START

Go to Engine FAQs, Chopper.<br /><br />Let us know what you find.<br /><br />Good luck.

 

[SuzukiChopper]

Re: 1972 Johnson 100HP... NO START

Well, good news. Got the two carb kits I needed, got new plugs, did all that work and went to fire it up... no go. My GF (who was also present and in the same place the last time), noticed that when I went to prime the motor a bunch of gas leaking from the connector to the motor. I guess yesterday I said that was because I had it over-primed (ooops). Swapped out that connector with another I had, primed, choked, turn key and it fired RIGHT up. WOOHOO! <br /><br />So we headed out to the lake to put the boat in the water, make sure all our hard labour paid off, left the dock, headed out a ways, checked for water, not a drop (phew). So I go to start off again, kicks into gear, dies. Tried about 8 times, died (am i going to have to paddle? ). So I pull the motor cover, set the idle higher, and finally got moving. Got up on plane and the boat wants to drop hard to the drivers side (100lbs extra and a battery I guess will do that). So no more fast, putted around for a while, stopped, went to leave and the same bogging happened again when I went to start out. So now my next question....<br /><br />There are four screws accessible through the air assembly and the labels state these are slow idle mixture screws. So I'm wondering if these need adjusting. My biggest issue is I'm used to motorcycle carbs, this boat carb stuff is a little different, and I'm wondering if those work the same way (loosen to go richer, tighten for more lean). Anyone have any ideas about those?<br /><br />And thanks to everyone who helped me get my boat running today, I'M SO HAPPY! <br /><br /><br />edit: I'm going to goto the engine FAQ's and read to learn, even if it doesn't involve my motor, thanks!

 

[REELSPORT]

Re: 1972 Johnson 100HP... NO START

You might want to try and turn low speed screws all the way in until they LIGHTLY seat and then turn outward about one turn. You will need the motor to be in the water for the next part which is ajusting the low speed screws. With the engine warm ajust each one by turning each screw inward or outward about one quarter at a time and allow about 15 seconds for the motor to adjust to last correction and adjust to the point where you get the high rpms with the motor running as smooth as possible. good luck

 

[SuzukiChopper]

Re: 1972 Johnson 100HP... NO START

Now these screws are pretty big screws and there are four of them. When they aren't seated they seem kind of loose and almost seems to me like they could adjust themselves from the vibration. I'll try losening them off and see how they feel and hopefully I can get it back in the water Sunday and see if the rest helps. Thanks!

 

[REELSPORT]

Re: 1972 Johnson 100HP... NO START

These four screws should be your high and low speed adjustment screws. You said that they were loose and could adjust themselves that means your packing is not doing the job. I think that you need to rebuild the carbs with new kits. This is a pretty easy job but I suggest that you get a manual if you dont have one and it will make a lot of things clear to you. good luck and keep us posted.

 

[SuzukiChopper]

Re: 1972 Johnson 100HP... NO START

Just did the carb rebuild. Sorry for this one last question (I promise I'll get a manual right away, just going to have the boat out tomorrow so was going to do this then). The packing you're refering to is the redish-orange o-rings correct? Not rubber but more a paper? If that's the case then I know exactly what the problem is and I can easily solve this before I head out. Thanks!