No Spark - 1963 Johnson 28 HP

[penguin529]

Hi,I have 1963 Johnson RXL-11a 28HP that has no spark in either cylinder. It seems that the problem is centering around the cut off switch assembly on the side of the motor. Can someone explain how the switch works and how to troubleshoot. Thanks Much!!

 

[racerone]

That switch cuts off one cylinder should there be a high vacuum.----You could disconnect the one wire and see if you have any spark.----Pull the flywheel and inspect the 2 coils.---Clean the points and replace the condensers.

 

[fdrgator]

Hi,I have 1963 Johnson RXL-11a 28HP that has no spark in either cylinder. It seems that the problem is centering around the cut off switch assembly on the side of the motor. Can someone explain how the switch works and how to troubleshoot. Thanks Much!!

If that motor is over revved in neutral (or if you break a drive pin or lose a prop), it will continue to rev and you can't slow it down. The vacuum cut-out switch senses that condition and shorts out one cylinder till it slows down, then goes back to normal operation. Note that it only kills ONE cylinder. Also, it takes a high vacuum to make it do anything----and you certainly don't have a high vacuum in a non-running motor. In other words, that is not your no-spark problem, and don't be disableing it.

 

[penguin529]

Thanks to all!!
I was able to get spark. I disconnected the wires on the center post of the cut out switch and pulled the flywheel and cleaned the points. Wiring wise this is what I found: a black wire (along with the green coil and condenser wire) on each of the point terminals, one of the wires went directly to the center term of the cut out switch, the other went to the kill switch first then to the center term of the cut out switch, on the corner post of the C/O switch was a white wire that goes to a micro switch next to the ignition plate that is activated by a cam. Seems to me both cylinders would be cut out with this setup???

I was able to get the engine to pop a few times with starting fluid but couldn't keep it going (fresh gas 24:1 ratio). I removed the carb to clean (previous owner said it sat for a few years) Carb looked good inside with exception of possibly the float (had a few nicks in the coating). I will re gasket and replace the float.

Any other suggestions?

What should the compression be?

The plug wire with the dot was on the top spark plug is this correct? It goes to the coil on the side with the C/O switch

Thanks Again!!

 

[fdrgator]

Thanks to all!!
I was able to get spark. I disconnected the wires on the center post of the cut out switch and pulled the flywheel and cleaned the points. Wiring wise this is what I found: a black wire (along with the green coil and condenser wire) on each of the point terminals, one of the wires went directly to the center term of the cut out switch, the other went to the kill switch first then to the center term of the cut out switch, on the corner post of the C/O switch was a white wire that goes to a micro switch next to the ignition plate that is activated by a cam. Seems to me both cylinders would be cut out with this setup???



The plug wire with the dot was on the top spark plug is this correct? It goes to the coil on the side with the C/O switch

Thanks Again!!

Dang it, No. What I said is true, but maybe I didn't say enough. The black wire from the top cylinder goes to the kill switch. The black wire from the bottom cylinder goes to the vacuum cut-out switch, then on to the kill switch. The coil closest to the front (forward) of the motor is the top cylinder. OK, rest of the story: When the vacuum cut-out switch activates, it shorts out the bottom cylinder only. The black wire from the top cylinder goes to the kill switch, that is true. But it doesn't go through the kill switch. It isn't connected to anything till you close the switch contacts When you turn the motor off, the kill switch connects the two black wires from both cylinders together. That shorts both sets of points together and kills the motor. I'm not finished yet... Under certain conditions, the vacuum cut-out switch may activate when not wanted, particularily at "cruise throttle" setting. That creates a high speed miss when it happens. To prevent that, the vacuum cut-out switch is disabled at any throttle settings above fast idle. That is what the micro switch does. Note that the vacuum switch body is not grounded because it is mounted on plastic. Not grounded, it can't ground out the bottom cylinder when activated. The micro switch grounds the vacuum switch body, but only at slow throttle settings. The micro switch does double duty on electric start motors, preventing starting at fast throttle settings. Believe me, I know what I'm talking about here.

 

[penguin529]

Thanks fdrgator for the full explanation that and the diagram help a lot! I have a shop manual coming from my library soon.

The motor is a true barn find complete with bird poop and a mouse nest under the cowl, I haven't found any evidence if the little buggers chewed through any of the wires.

Not electric start, considering attempting retrofit after pull starting today about 100 times. The flywheel has teeth and the starter mounting bracket is there.

Yes torqued to 105, went 30/60/90/105 bs.

All I have is an inline neon tester, I will see if my local parts store has the gap tester.

What should the compression be? I know it has some, pulls much easier w/o plugs in.

The metal parts of the coils are green the plastic covering the coil wire itself is black, no visible cracks, i believe there was a "m" embossed in the plastic.

 

[fdrgator]

Compression sounds ok. Coils sound like they have been replaced--(that's good). The "M" in a square is OMC's trademark, meaning you have OEM coils, not aftermarket. Never pull a starter rope 100 times. If it isn't running after 5, there is something wrong. Stop pulling, do some troubleshooting, and fix the problem. One last time, the vac switch is not the problem. That is next to impossible. It has a large spring inside, holding the diaphragm & contacts in open position.

 

[penguin529]

Installed new points and condensers, got her running.

Spark would not jump 1//4" gap, but did jump plug gap so i gave it a shot. Any suggestions for stronger spark? New coils/wires?

It was rough when running, had it going 5-10 minutes (in a tank), noticed water was no longer (was when I started) coming out of the upper outlet (?) hole so I shut it down, fogged with Sea Foam in carb and plug holes.

Thanks Much!!