help! 1974 johnson 15 hp

[caldog101]

my buddy just gave me a 1974 johnson 15 hp motor i know it needs carburator work it has been sitting for a while my concern is i don't have any spark what should i be looking for the motor is in excellent shape and compression is 90 on both piston do i have to remove the flywheel and what am i looking for any help would be appreciated thanks

 

[Bear]

Re: help! 1974 johnson 15 hp

Check this link web page

 

[steelespike]

Re: help! 1974 johnson 15 hp

Look for a kill switch disconnect it and check for spark.

 

[NathanY]

Re: help! 1974 johnson 15 hp

You should be looking for the manual for that motor on the iboats Marine Mega Mall.

 

[caldog101]

Re: help! 1974 johnson 15 hp

thanks bear for the website just what i was looking for and yes i need to get a manaul i have 3 others but not for that year and hp guess i got a little ahead of myself thanks again

 

[songdog]

Re: help! 1974 johnson 15 hp

I have a 1974 'rude 9.9 which had similar sypmtoms. Check/ replace the driver coil and inspect the primary coils(mounted to power head) for cracks in the insulation. My motor was in storage from 1976 until 2002 and we brought it back to life. Good luck.

 

[caldog101]

Re: help! 1974 johnson 15 hp

thanks for the info songdog just got a manual and changed the points and condenser still no spark that driver :LOOKS: GOOD but i guess it's my next part to try out i gapped the points to .20 like the book says but not sure if i did it right turned cam till it got to the highest point and gapped it there let me know if i am missing something

 

[caldog101]

Re: help! 1974 johnson 15 hp

also the motor is in very good shape no can't hardly find any rust and living in miami it's obvious it has never seen salt water i took a compression test( pulled the rope about 4 times each and both cylinders were 90 any help would be appreciated

 

[caldog101]

Re: help! 1974 johnson 15 hp

for songdog where would the water outlet be on this motor can 't seem to find ?

 

[Boatist]

Re: help! 1974 johnson 15 hp

Caldog<br />Make sure you disconnect the stop switch and try it. It just unpluggs. Check for spark on both plugs, if no spark on either plug probably a bad driver coil. Also make sure the flywheel Keyway is good and installed. With the exception of the stop switch and driver coil every other part only affect one plug. If one plug has spark and the other does not you can swapp coils with out removing. Swapp spark plug wires and also the input pulgs to each coil. You gapped the points correctly. If you have spark on both then can be flodded or no fuel either. Motor has no pee hole, water comes out two places. Holes above the cavitation plate and at back of motor just below the cover a large 3/8 inch hole. This hole will get no water out if on muff but in a tank or on the water it will. My 1975 has 120 lb of compression.

 

[caldog101]

Re: help! 1974 johnson 15 hp

thanks boatist, i disconnected the stop switch but still no spark i am going to change the driver coil i want to make sure i have spark before i tackle the carbs and the impellor will it be ok on the motor if after i change the driver coil squirt a little 2/cycle gas in the throat of the carbs just to see if it will fire up it will probable be running for a second taht way i'll be sure i have spark and can continue on to the carb and impellor or should i just pull to see if i have spark thanks

 

[sailor_turned_stinkpotter]

Re: help! 1974 johnson 15 hp

Caldog when you think you have some spark go one better and spray your gas/oil mix right into each cylinder then replace plugs and give her a pull.....

 

[Boatist]

Re: help! 1974 johnson 15 hp

Caldog<br />Does not matter how you try it. For me I would check spark on both plugs. Not hook up gas and squirt 2 cycle mix in both cylinders. Put plugs in and pull the till it starts. When you put in the driver coil make sure not hitting the flywheel but still close.<br />Good Luck

 

[caldog101]

Re: help! 1974 johnson 15 hp

thanks boatist i ordered the driver coil but i was told that it is important to measure the "air gap" between the driver coil and the inside of the flywheel they sell a gauge tool when you take off the flywheel you put this on instead and that way you can see and measure the "air gap" BUT they don't make them anymore and when you put on the flywheel naturally it covers both driver coil and inside of flywheel so what should i do now and thanks again for your help and songdog and boatist

 

[alcan]

Re: help! 1974 johnson 15 hp

Hi Caldog<br /> You will notice the mechined bosses on the stator plate, whhere the coils mount. Just make sure the laminations of the coil are even with these bosses. I use the end of a steel rule for a straight edge to help check. When all looks even and true, carefully set the flywheel on making sure there is not rubbing. Rotate by hand a couple of times to make sure. Go ahead and test for spark before torquing the flywheel. With the spark plugs out You can spin the engine with finger tips on top of flywheel.

 

[Boatist]

Re: help! 1974 johnson 15 hp

Caldog<br />On my engine coil never failed but I did try adjusting it by marking position where it was then moveing it closer and turning by hand. then backed it up slowly until it did not hit and then marked again and moved back about another .010. Tightened down turned by hand again made sure all was tight then tightened down flywheel and has always worked fine.

 

[caldog101]

Re: help! 1974 johnson 15 hp

thanks guys waitng on parts will keep you informed

 

[caldog101]

Re: help! 1974 johnson 15 hp

THANKS ALCAN did exactly as you told me and "IT WORKED" !!!!! I have one good coil and i switched both wires coming from underneath the flywheel and both spark but i am going to wait till i get both coil I'll let you guys know whats happening

 

[caldog101]

Re: help! 1974 johnson 15 hp

well guys I'm back got new coils and plugs started it up and the motor ran and it would rev but would not rev or "wind up" very good so i decided to a carburator over haul iwas told that my high speed may be clogged so i would change everything but after the overhaul it would not start so i take it apart again and adjust the float now the first time i tried to start it again when i pulled the cord it made a one "BACKFIRE" and it was toward the end of my cord pull the it backfired i got a lot of help from bear and songdog,alca and boatist well i could go on on so any help would be appreciated "what up with that manual starter spring the #$%&^%itch almost took my eye <br />out"

 

[Boatist]

Re: help! 1974 johnson 15 hp

Caldog<br />Yes the manual return spring is dangerous I always hold it together with rubber bands but if careful can do with hands. Manual says to use a putty knife.<br />I think you said now have spark but will not start. I would suggest checking the flywheel keyway and make sure it did not sheer when it backfired.<br />Also motor can flood if float not shutting off fuel. Once it flood takes half a day at 100 degrees to clear fuel out with fuel hose disconnected. If you still have spark and the flywheel keyway is ok (sheers easy if do not get flywheel torqued down right) then I would take off fuel line pull the plugs and let air for several hours. squirt one shot of 2 stroke mix in each cylinder. Put plugs in and try to start. If it starts will run at least 5 minutes with out fuel line. When mine was flooding one summer day 90 plus degrees I pulled the gas line off took plugs out and laid in sun took the carb off cleaned and blow out checked float adjustment put Carb and Manual starter back on. Left gas line off but squirted one shot of mix in eaach plug. Then put plugs in and it started and ran over five minutes with out any fuel line. This is when I found out that when it flood like mine was doing the lower end rods and bearings can still have a lot of fuel and run for 5 minutes even with out a drop of gas in carb. The fix for mine was a new float one that actually does float.<br />Good luck