Need help bringing a Johnson 20R273A back to life

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

It sounds like your throttle linkages are binding,I find it is very rarely the return spring.
If your throttle binds,it will leave the carb flap open at the highest point you have turned the throttle to,then settle as it frees.
I'd have a look at your twistgrip,if that binds,your throttle will be left wide open.
The advice off joreeves will be relevant to the engine 'hunting' like it is in your video.(carb tuning)

Joereeves- Thanks for the detailed carb adjustments procedure. The service manual said to start at 1 1/4 turns which I did so I'll back it out to 1 1/2 and start adjusting from there. Also in all of my online research I read about a problem these motors are prone to with the magneto plate wobbling and a procedure you developed to correct it. That's something I intend to check for as well.

Valvebounce- thanks for the tip. I'll start inspecting/disassembling/ cleaning the linkages until I get a stronger throttle closure. I'll also look at the twist grip. The previous owner put a rattle can paint job on it and there's paint all in the gears on the twist grip. I'll clean that up. Also, if I start it and it over revs again I'll try manually closing the throttle on the carb body. If that works I'll know that it's the problem.

Can you free up the pivot point then lube with some lite grease? May not need any more tension as it will cause excessive follower/roller wear.

After a bit of cleaning I got the throttle arm on the carb operating properly. I also found that the plug wires may have been catching on the engine block and preventing the throttle gettin closing so i installed a keeper to keep the wires from binding. Not sure if the wires are routed properly or of the proper length. I matched the routing and length of the wires that came with the motor and they certainly could have been wrong. I'll try to pay pics of my wire routing.

I looked in the manual to see if I could find a procedure for adjusting ther throttle linkages. Didn't find anything. Found a video on YouTube that said the bullet bearing on the throttle arm should be adjusted so that at barely open throttle it rests between the 2 hash marks on the throttle cam. Is that correct?

I think I figured out a good way to route the wires so that they don't bind the throttle or chafe anywhere

Good, the carb throttle butterfly should begin opening between those 2 marks. There may be some small amount of play to compensate for so the actual point of contact will possibly be just before the 1st mark.

Thanks Timguy. I adjusted it to open between those marks.

Next question. The stop screw at the gears at the base of the tiller handle is adjusted all the watt out on my motor. Should I adjust it in to stop the twist grip to a certain point? Do I just use pliers to turn that adjustment screw?

Just found some reference photos in the manual and it looks like I have the plug wires routed completely wrong. Mine go to the port side when they should go starboard. That's what i get for assuming they were right the way I found them. Will work on that later I think I cut them to short to work that way.

Some like to back it all the way out so you can stop the motor without the kill button. That's my preferred method. Of course you can set that as your slowest idle too, then use the button to kill. Do this when your all dialed in on your low speed mixture, and all other factors are stabil. This is your final step. Some adjust when in neutral (recommended), others like to adjust to a slow troll while in gear. Trouble with the second method is that a neutral idle may be a bit high when shifting into gear.
Wires too short now?

If your carb butterfly is going from fully shut to fully open at the moment,you don't need to touch the screw.
It sounds like your throttle roller is in the right position.
Make sure your ht leads don't touch the engine block,they will melt and short out.

Timguy- I think I'll go with the first method for now at least until I get it running and idling well. And I ran out of shop time today but yes I think there's a good chance the plug wires are too short.

Valvebounce- now that I've seen a picture of how they're supposed to be routed I should be able to keep them off the block.

So after adjusting the throttle I got it started again. The good news is that it didn't rev out of control so it looks like that was a throttle issue.

Once I got it started it was running the same as in the video. Coughing or hunting as valvebounce called it. Required the throttle to be feathered to keep it running. Started at 1.5 turns out on the low speed needle and started trying to slowly adjust it inward to see if I got any positive change per the carb adjustment procedure. Never could get it to stop coughing and when I got to about 1 to 7/8 turns I couldn't keep it running despite feathering the throttle.

While it was running I did notice a fair amount of wobble in the mag plate. Don't know if that's causing the cough but I'll address it using the 12-9-6-3 procedure.

I started to suspect that it was missing the spark intermittantly. I pulled the flywheel to inspect all my connections for the ignition system and I think I found something that could possibly explain my symptoms. It looks look the threaded holes in the flywheel that you screw the puller tool into have been heli coiled at some point. The bottom of the heli coil wire was sticking out just a bit proud of the underside of the flywheel. It stuck out just enough to rub on the plastic outer casing of the new coils. It ground of a bit of the casing on each coil about 1/4 the size of the finger nail on your little finger. I don't see exposed coil wire but I do see black rubbery insulation exposed. I wonder if the spark is intermittantly grounding out to the under side of the flywheel and causing it to cough/ stumble?

I did clip the wire of the helicoil so it won't contact the coil in the future.

It sounds like there might be something sticking or blocked in the carb,try checking the bowl/fuel cut off pin,and your float height.If the bowl is flooding,the carb won't be able to be tuned.Too much fuel will make the engine run rough.(like in the vid)
If you use a thin layer of two part epoxy on your coils it should reinsulate them.
Make your new ht leads a bit too long,you can cut them shorter when you have the correct routing sorted out.

I'll pull the carb and double check it when I get a chance. Unfortunately domestic duties call for the rest of today. My wife is remarkably unconcerned about whether or not my outboard is running smoothly It'll be Wednesday before I can work on it again.

My advice is to get her going on fishing, I got a great beer batter recipe for you.....you do all the cooking and cleaning for that fish dinner. Have a nice glass of wine ready......if you drink.

You know what? She'll be handing you tools the next time you tune up that 20. Fishing pole in her other hand. Just like my wife....

My wife grew up in Jacksonville, FLA next door to her grandparents who had a big house with a dock on the St Johns River. Her dad and grand dad both always had boats. She has definitely done more boating and fishing than I have. She's excited about us having a boat for fishing,
boating, camping etc. And she loves to eat fish and wild game (I hunt too) so I'd love to get that beer batter recipe. And we both like a glass of wine or two with dinner!

But our baby boy hasn't been sleeping well which means nobody is sleeping well. She doesn't tolerate the sleep deprivation as well as I do. So she's not excited about anything at this very moment except getting the household chores done early and figuring out how to get that kid to sleep. While I'm on the outboard forum she's on the mommy forum.

Won't be long before he is borrowing your boat and car Haha.
If he is teething,it's always a sleep deprivation period.

Just to add,if the insulation on your coils is thinned out with the wear off the heli coil,there is a chance that it will short out even with the helicoil wire trimmed off.It could jump through the remaining insulation.
So to make sure,using two part epoxy (in tubes)like suggested might save you a lot of trouble.

I think I figured out why it has been coughing and stumbling. After double checking that the carb was operating well/proper float level/ nothing blocked or sticking I reinstalled the carb and started the motor. This time I noticed fuel spraying out of a hose that the parts diagram calls the "manifold to cover" hose which appears to be a crank case ventilation hose. It was torn right where it attaches to the nipple on the crank case at the front of the motor under the carb. I replaced the hose with some spare fuel line I had laying around. Not the best fit because the nipple at the crank case end is much larger than the nipple at the manifold end. I clamped it on as best I could and started the motor. No more coughing at any RPM. Idles and revs normally. I fiddled with the low speed needle a bit and it appeared to respond to my inputs normally. Looks like that the leaky hose was causing a lean condition which caused the symptoms I was having.

Unfortunately that hose which is larger on one end than the other is $21.00, but it's well worth it to finally get the motor running right. I'm going to get that hose installed and mix up a fresh batch of premix fuel before I do the final low speed needle adjustment. Then a few more maintenance items like replacing the lower unit oil, the impeller and the thermostat.

After fiddling with it a bit I managed to slip a bit of the tiny fuel line that fits the smaller nipple into the larger fuel line that fits the larger nipple. It was tough getting it in there but resulted in a very secure friction fit. Cost $1 for the tiny fuel line from Ace Hardware instead of $21. Plus I don't have to wait for it.

Excellent.
Cut fish into uniform size. Batter is a "complete" pancake mix like Aunt Jemima or Krusteaux. Add a tablespoon of corn starch for bonding agent and season to taste with salt and pepper. Add a bit of lemon or lime juice. Then add your beer to a consistency of a thick pancake. Get your vegetable oil to temp, say 360F. Dunk fish in the batter ahead of time as you fry, lowering them gently into the oil so the coating doesn't float away. Heavily guard your draining cooling area so your wife won't get away with too many free samples. Serve with tarter sauce or ranch dressing, whatever you prefer. I love 'em straight, maybe with a couple more drops of lemon or lime juice! I'm getting hungry already.

Glad you found the problem Mike.
I use a heat gun or hot water to get pipes to fit.Sometimes I use shrink tube over the joint for a good seal.
I've used shrink tube on ht leads at wear points.
Multi dia packs are handy to have around.

Iv'e noted your recipe Timguy,thanks.

Timguy- Thanks for the recipe that sounds delicious. I'll just have to make sure not to sample to much of the beer (for flavor purposes of course) while cooking. Once I finish getting the motor, boat and trailer fully operational then I just have to figure out how to catch fish

Valvebounce- the idea of heating up the fuel line to get it to slip on to the nipple easier is pure genius. I've always thought there must be a better way than just fighting it. Can't believe I didn't think of it. And I will definitely be putting some heat shrink over the joint of the two lines... another great idea.

Our sea fishing season is just staring to pick up here in the UK.I have to trailer my boat at least 70 miles to get it on the water.
Just in the process of putting a 1999 25hp Johnson on it.
I've made an anchor bouy out of a 5 gallon drum.I've got a bit too old to drag the anchor up out of the mud etc.Haha.

My newly installed kill switch isn't working. Instead of paying $110 for the factory part, I bought a "momentary" push button switch from the parts store for $10 that is water proof and fits nicely into the factory switch opening. The previous owner just had the 2 connections from the kill switch wired to the breaker points. When you push the button it closes the circuit between the 2. I assumed that it would ground them out and prevent spark going to the plug. But it doesn't work.

I looked at the wiring diagram in the manual, but I'm not good at reading them. Does each wire from the kill switch split in 2, with one side connected to the breaker point and one side grounded to the magneto plate?

Mike from Atlanta said:

My newly installed kill switch isn't working. Instead of paying $110 for the factory part, I bought a "momentary" push button switch from the parts store for $10 that is water proof and fits nicely into the factory switch opening. The previous owner just had the 2 connections from the kill switch wired to the breaker points. When you push the button it closes the circuit between the 2. I assumed that it would ground them out and prevent spark going to the plug. But it doesn't work.

I looked at the wiring diagram in the manual, but I'm not good at reading them. Does each wire from the kill switch split in 2, with one side connected to the breaker point and one side grounded to the magneto plate?

Click to expand...

Electrics are not my forte' but I imagine the switch breaks the low tension circuit to the coils.
I don't think it grounds,it just breaks the circuit.

I was hoping that after all the time and effort I put in to getting the power head sorted out, I'd luck out and have a well- sealed gear box. No such luck it seems. Finally got around to drawing the gear box just now. When I initially loosened the drain bolt, a bit of pure, clear water came out. Once I fully removed the drain bolts out came some tan, creamy sludge. Looks I'll be learning how to replace all the seals in the gear box. Hopefully it isn't terribly difficult.

Took off the prop and found that the drive pin is broken. Also removed the thermostat cover and found that there was no gasket under the cover and the thermostat was stuck open. Looks like this motor has seen some hard times.

Time to order the next round of parts. It'll be next weekend before I have any significant amount of time to work on it.

The stop wires are attached at the points and ground them out when you hold in the button. The water infiltration could be at the prop shaft seal, might be a stroke of luck. Get yourself that thermostat and let us know how she runs. Great motors. I pressure test to 10 or 15 psi with the lower unit completely drained. Often see a shift shaft seal leak, but sometimes they won't bubble unless you move them around through the gears.