Logo
FULL SITE MENU

Need help bringing a Johnson 20R273A back to life

VB, you bet, any coil will work, keep voltage below 10,000. This is not a new technique. I learned it from my mentor, Bill Swanson Bay View Boat Works, Duluth MN. He specialized in OMC products and worked alone with his wife, right on the shores of Lake Superior's St. Lewis bay. Bill, even after all these years since he died, is well remembered for his honesty and skills at his business. He also sold new Johnsons/Evinrudes. He worked until he died and his nephew messed up the business, he had limited skills. I really could have bought his business, as my Dad well supported my interests. The problem was that Bill was not set up for auto repair and body work. Living on the bay, it was simply house to house, no room and his business was grandfathered in.......couldn't expand from what he already had.
 
Last edited:
Thanks for the info TG.
As a bricklayer I have missed similar opportunities.
This site is jumbling up my typing,has been for a few days now.
 
I have also extensive experience in block laying, bricklaying, and even as a general contractor on smaller commercial construction jobs. Built 2 radio stations and several houses, garages, barns. I truly enjoy masonry work. My passion has always been marine, however. My MO is to find someone who excels in a particular trade and follow them. Study, work with and embrace their knowledge and experience.
 
I have a construction background too. I was a carpenter and remodeler for about 15 years. Opened up my own general contracting business in 2006, just in time for the economic collapse of 2008. Couldn't find enough work to keep gas in my truck after that. Went to work for another guy as a carpenter and started college at night at age 30 to become a registered nurse. The ultimate recession-proof line of work. Don't regret learning how to build things though.

Thanks for the tip timguy I'll see if I can find one of those igniters to test the condensers. I've hit a bit of a time crunch with work, baby and school (almost finished with the next nursing degree). As soon as I can make it happen I am going to clean/gap the points and reassemble. If I don't get strong spark I may just start throwing parts at for the sake of getting this thing running sooner rather than later. Once I get the ignition and carb back in working order I still need to check out and possibly replace the impeller, lower unit oil, fuel pump and thermostat that I can think of.
 
Yup, good business, lots of us "baby boomers" needing care now. Just got home yesterday with my new anterior installed hip. Gonna cost my insurance about 50 grand. Ouch! Asked my surgeon if he could install a heavy duty model with grease fitting. Told him I still wanted to carry my 30 Johnson longshaft electric start. He said to trade it in for 2 15 hps. The medical service industry is surely the right move.
 
Just like motors, mechanics need periodic rebuilds. The parts are just more expensive. And you don't even get a core refund for the old hip. Good luck with your new hot rod hip!
 
Thanks, Mike. These helpers on the forum have hundreds of years experience.....and that's probably just considering Joe, Racer, and a couple others.
 
Finally got a chance to spend some time in the shop today. Reassembled the ignition system. I think I did it right but not sure. The manual says to use a special bullhorn-shaped tool #383602 to rotate the crankshaft to the correct position for each point before setting the gap to .020. Do I have to have that tool to do it correctly? Is there another way? I "eyeballed" it as best as I could so that the "top" mark on the crankshaft lined up with the proper index marks. Am I correct in thinking that the goal is to set the gap with the cam lobe at it's highest against the breaker point? I think I did that.

Cleaned the points and got everything back together and still don't have strong spark. Still sparking but won't bridge the 1/4 inch gap. So I'm back where I started.

Because I'm not very confident in my electrical diagnostic skills, and because most of the components look old and worn, I'm thinking that I may just order all new coils, condensers, breaker points, plug wires and boots for about $100.
 
I set mine watching the lobe for TDC the same.
I would buy new coils,HT leads and plug caps.If the points aren't burned,they will be ok,and so will the condensors.
I always take the points out and clean the base plate.
I suspect your coils are your problem.
 
Istead of the tool you can use the timing marks on your flywheel.-----After all the tool is a " dummy flywheel " and it is a time saver.----Yes your flywheel has timing marks.
 
Once your points are closed you should check continuity with a simple multimeter. There should be no resistance. In other words, perfect continuity. Spark coils can be checked with your multimeter too, but in certain rare instances your coils can arc internally causing weak or intermittent spark. If spark is weak on both coils equally and the ohms test out within specs, then I might focus on the points instead. If you should decide to get new points, it is a "given" to get the kit which includes condensors. I only recommend "dressing" points once. Perhaps the original points have already been removed and dressed. If the silver contact surface has been mostly removed, then continuity will not be adequate and weak spark will result.
 
Last edited:
Im having difficulty figuring out which spark plugs to order to fit the 20R73A. Finding some confusing stuff online. Does anyone know which plugs I need? Are they available at a local parts store or will I have to order them?
 
I run J6C in mine, but troll it a lot. J4C work great with my leaner synthetic Amsoil mixture too with premium non oxy fuel. Start with J6C and you will not hurt anything at 50:1. Monitor plug color.

The plug heats are arguably adjustable based on fuels, oil type and mixture, as well as operational parameters/conditions/requirements. If you run mostly WOT at 50:1 on top quality oil, you can go J8C. R designation plugs have a built in resistor which I avoid. Why? Some say the resistor plugs were more engineered for high energy spark ignition systems.

For me, I prefer straight non resistor plugs on anything using breaker points. Why? Longevity and dependability. Resistor plugs are more of a "suppression" thing and not needed in these old applications unless you are getting spark interference on your electrical equipment, like marine or entertainment radio, GPS, or cell phone.

Breaker points on their own account, can cause interference issues and the idea to suppress spark at the plug, may not correct the disturbance.

A 5 or 6 thousand ohm resistor is incorporated in resistor plugs which may effectively reduce spark "snap" and overall spark power in low energy ignition systems. Take this with a grain of salt, however. Even a low energy system, when healthy, can provide more than adequate spark, through a 6 thousand ohm resistor. Its just that at some point that resistance may be the difference between having to change a plug out in the middle of a storm. Also note, that resistance may vary as the spark plug ages and wears.
 
Last edited:
Update....WE HAVE SPARK!!! Parts came in yesterday and I unexpectedly got the day off work today. Replaced coils, condensers, points and plug wires. Even replaced the oiler wick. Cleaned up the magneto plate and the magnets on the inside of the flywheel. Set the point gap to .022 (manual says .022 instead of. 020 when you replace the points to allow for wear- in). Got bright spark across a 1/4 inch gap with loud snap on the top plug. Couldn't get 1/4 inch but maybe a hair under 3/16 still with loud snap sound on the bottom plug. Tomorrow I'll double check all my connections for the bottom plug to see if I can improve the spark a bit.

Got the carb rebuild kit and new fixed orifice in too so I disassembled the carb and have it soaking in carb cleaner overnight. With any luck I might have this thing running by the end of the weekend!
 
Got the carb reassembled and installed yesterday. Set the low speed needle at 1.5 turns out from seated. Also replaced the old, stiff fuel lines while I was at it. Set up the trash can test tank and connected the fuel line. Primed the line and noted fuel leaking from between the fuel pump cap and fuel pump body. Wasn't sure if I was getting any fuel to the carb. Removed the carb bowl drain plug (I wish it was in a more accessible spot) and no fuel drained out. But I decided to try a test run anyway. Plugged the choke and pulled a bunch of times... nothing. Sprayed some fuel into the carb and pulled a couple of times and it fired up and ran for a few seconds!! So I believe this thing will run if fix the leak in the fuel supply.

Tightened the screw that holds the fuel cap on a bit but it still leaked. Tightened it a bit more and snapped the screw. I'm going to look into cost of rebuilding vs replacing the fuel pump. Hopefully once I get that sorted out the old girl will run!
 
The fuel screen cover/inlet is a common leak point. Most original cap screws that retain them are cut to accept a coin as a screwdriver. Perhaps that's just a crazy idea to attempt to keep people from using more powerful tools and overtightening.
 
Got the carb reassembled and installed yesterday. Set the low speed needle at 1.5 turns out from seated. Also replaced the old, stiff fuel lines while I was at it. Set up the trash can test tank and connected the fuel line. Primed the line and noted fuel leaking from between the fuel pump cap and fuel pump body. Wasn't sure if I was getting any fuel to the carb. Removed the carb bowl drain plug (I wish it was in a more accessible spot) and no fuel drained out. But I decided to try a test run anyway. Plugged the choke and pulled a bunch of times... nothing. Sprayed some fuel into the carb and pulled a couple of times and it fired up and ran for a few seconds!! So I believe this thing will run if fix the leak in the fuel supply.

Tightened the screw that holds the fuel cap on a bit but it still leaked. Tightened it a bit more and snapped the screw. I'm going to look into cost of rebuilding vs replacing the fuel pump. Hopefully once I get that sorted out the old girl will run!
 
Right, and make sure you got a fresh gasket. The black rubber composition ones may look good, but in reality have hairline cracks.
 
IT LIVES!!! Got the new fuel pump installed last night. Fuel leak is gone. Primed the fuel line, cooked it and started pulling the cord. I got some stumbles and short 1-2 second runs but no consistent running. Did some experimenting with different choke and throttle settings with the same result. Finally ended up spraying some fuel into the carb and got it to start and run.

While running it "stumbles" or "misses" frequently especially at low rpm. Any ideas where I should start with trouble shooting? Carb float level? Exhaust plugged? Ignition timing?

I got a short video clip of it running. I think I just figured out how to post a link to a video I'll work on that.
 
Also, it won't idle on it's own without feathering the throttle. I did however confirm that it will go into forward and reverse gears positively, does pump water out the tell- tale and the new kill switch I just installed works.
 
I have a new symptom and I'm not sure if it's related. I started the motor again and this time it revved out of control. The throttle didn't seem to have any effect. Kill switch slowed it a bit but wouldn't kill the motor. I quickly pulled the plug wires off to stop it from running itself to death.
After that I started looking around the carb to see if there was an air leak where the carb mounts to the motor. I did notice a bit of fuel under the carb. Any thoughts?
 
I doubt there could be an air leak big enuff to let the motor run out of control !!-----Check the flywheel key.------Check and make sure nothing is broken on throttle linkages and parts.
 
Thanks Racerone I'm off work again tomorrow I'll check the linkage and flywheel woodruff key in the morning and post what I find. It only raced like that for a few seconds so hopefully it didn't do any damage.
 
Could a weak throttle return spring cause it to over rev? Could the vacuum created by the motor at high rpm open up the butterfly and hold it open despite twisting the throttle grip? I've noticed my throttle doesn't snap shut briskly. Will look into that in the morning.
 
That could be, but I've never seen that in all my years. Just place throttle on idle setting with motor at rest, then check for free, smooth operation using your finger. It should snap back from WOT position without hesitation or binding.
 
Thanks Timguy. It is definitely sluggish and doesn't snap back. I'll see if I can put more tension on the current spring or find a replacement at Ace Hardware. If not I'll order one. I'll also check the service manual to see if there's a procedure for adjusting throttle linkages. At this point I'm a bit gun shy about starting it till I figure out the problem. Don't want to over rev and kill the motor.
 
Back
Top