Johnson 1962 40HP (RK-24?) no spark at plugs

[michaeltaylorms]

Hi. I am completely new to this, but recently bought an old boat with the above mentioned motor, and I have a factory service manual. The motor was very well maintained and used frequently by the previous owner. It started and ran perfectly both before and after I bought it. So I think my problem my be some kind of user error.

The first time I took the boat out, it started with a single turn of the key, idles and ran perfectly for 25 minutes. I had the throttle wide open for about 5 minutes when the engine suddenly died. It did not sputter or cough, it just shut down, and it has not started since.

I originally thought maybe it was bad fuel and fouled plugs.

Since then I have replaced the fuel, checked plugs (which were new), and verified compression. I have a new battery. I bought a spark detector, and as best I can tell there seems to be no spark between the magneto and the plugs. The points and condensers look new, and it seems strange that they would go bad for both cylinders at exactly the same time anyway.

I am at a bit of a loss, so any ideas would be appreciated. I have a feeling I maybe doing (or have done) somthing simple and stupid.

Thanks.

Mike

 

[F_R]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

So, I assume you have the flywheel off? And the key is not sheared? That sort of indicates there is a fault in the kill wires, the two black wires coming from the magneto and going to the ignition switch. Just disconnect one of them and see if you get spark back. (The key switch connects the two blacks together to stop the engine)

 

[spy1309]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

Michaetaylorms by any chance you have the manual in electrinic format? My engine is 1960 like yours identical and the closest manual I got is 1969.

 

[michaeltaylorms]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

I did have the flywheel off, and the key was not sheared. It tries to start, just doesn't get there. I will give this a try and let you know.

 

[michaeltaylorms]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

Michaetaylorms by any chance you have the manual in electrinic format? My engine is 1960 like yours identical and the closest manual I got is 1969.

I just have a bound hard copy, sorry. The previous owner gave it to me when I bought the boat.

 

[samo_ott]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

I would have said something with the kill wires also but if it tries to start and/or sputters then it's not. If there's no spark though how can it be trying to start?

 

[crtboston]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

Hi,
Looks like you know about engines.
I have 1992 28 HP SPL. I had "an expert" work on it.
He put Ignition module, he got from eBay, that work 2 hrs & quit.
Could you tell me how much work involved in replacing power pack.
I guess I have to take flyvheel. The boat on the floating dock, & kind hard to get it to the real repair tech. to rework. Is it real to replace power pack without taking boat to marina?
Thanks
Gene

 

[samo_ott]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

crtboston, please start a new thread and pose your question as it does not pertain to the 40hp that was originally in this thread.

 

[michaeltaylorms]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

I would have said something with the kill wires also but if it tries to start and/or sputters then it's not. If there's no spark though how can it be trying to start?

the starter turns it over but it appearsthat the plugs are not firing. I did replace the plugs just to be sure. The spark tester does not light up when placed on the wires to the plugs. Neither plug seems to be getting any spark. But they did originally. Just stopped suddenly for both cylinders.

 

[F_R]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

Back to my last reply: Have you or have you not removed the flywheel AFTER it quit running?? I think it sheared the key due to being improperly installed and torqued.

 

[CharlieB]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

If this is a dual point and even one set of points is dirty then it will not fire.

Points can LOOK clean but still fail to have an electrical connection, Carefully slide a CLEAN piece of paper between the contacts, the paper will wipe off any accumulated dirt of oil from your finger and clean the points.

 

[F_R]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

Not so on this one. It has two sets of points, completely independent of each other. Actually completely dual ignition, so that's why there are very few things that will instantly kill both at the same time.

 

[Joe Reeves]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

The flywheel nut on that model must absolutely be torquued to 105 foot pounds. Anything less will result in a sheared flywheel key (out of time).

Spark plugs should be either Champion J4C or J6C plugs, gapped at .030. The J6C may provide improved performance due to the engines age and the poor quality of gasoline we're using now.

(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubber portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

 

[samo_ott]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

If not the key then it must be something with the kill wires if there is no trace of a spark.

 

[michaeltaylorms]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

Back to my last reply: Have you or have you not removed the flywheel AFTER it quit running?? I think it sheared the key due to being improperly installed and torqued.

I have had the flywheel off now twice since it stopped running. I guess I don't know what it means for the key to be sheared.

 

[F_R]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

The half-moon key that goes in the slot in the shaft and engages the slot in the flywheel. Does it do that or is the key sliced off flush with the shaft? The flywheel has to be aligned properly with the shaft or you won't have any spark. The key is what alignes it.

 

[michaeltaylorms]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

The half-moon key that goes in the slot in the shaft and engages the slot in the flywheel. Does it do that or is the key sliced off flush with the shaft? The flywheel has to be aligned properly with the shaft or you won't have any spark. The key is what alignes it.

I didn't notice any half moon key at all. And I didn't see anything about it in the flywheel assembly diagram in the manual which I consulted before removing the flywheel, but like I said I probabky screwed something up. I did notice that the top of fhe shaft was ground down recently. This seemed strange and troubling to me when I noticed it.

 

[captk]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

even if the key was sheared you would still have spark. The engine would not run but you still have ignition.

 

[Joe Reeves]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

Notice the key in the left side of the crankshaft taper here. Your crankshaft is different but the key would look the same, just somewhat higher up the taper.

 

[michaeltaylorms]

Re: Johnson 1962 40HP (RK-24?) no spark at plugs

Notice the key in the left side of the crankshaft taper here. Your crankshaft is different but the key would look the same, just somewhat higher up the taper.

okay the key is not sheared on the crankshaft. I will try a more careful flywheel installation with the proper torque. But assuming it was installed correctly when I bought it (because it started and ran perfectly) I am still not sure I understand what may have happened to suddenly kill both cylinders at once and impede spark to both plugs at the same time.

Thank you all though for the responses so far.