At the ignition switch... there should be a lone black/yellow wire leading from the wiring harness (kill circuit) attached to the raised "M" terminal.

There should be a lone black wire (ignition ground) attached to the remaining regular type "M" terminal.

There should NOT be any other wires leading to either terminal.

Temporarily remove the black/yellow wire from the ignition switch. remove the spark plugs so as to obtain the highest cranking rpm. Test for spark. Do you now have spark?..... and if so it should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it?

NOTE: Testing for spark via using the spark plugs is a waste of time.

Note that the engine's ignition is self contained and requires that the engine cranks over at least 300 rpm in order for the stator to generate the proper AC voltage to the powerpack's capacitor. A slow cranking engine will have either weak, erratic, or no ignition/spark. Let us know what you find.

1992 Johnson 40 hp

I have two yellow/black wires..one goes to engine and other goes to warning alarm. Do I disconnect both? Also when I do what you suggest and if I still don't get spark , how do I check rectifier regulator. Does the rectifier regulator affect spark?

Personally I have never come across a charging circuit wiring diagram, including that of a straight rectifier or a voltage regulator/rectifier that would have any bearing on the ignition circuit.

Does this engine have the warning setup with lights and gauges that function when you turn the key on?

I had the misfortune to needing to retire in 1991 and at that time the only other black/yellow wire led to the dead man's switch.... in which case I always disconnected it to eliminate any possible accidental ground.

You could also disconnect the black/yellow wire directly at the powerpack BUT make sure that it is the black/yellow wire that leads to the ignition switch.

With that wire (the kill circuit) disconnected... should you still NOT have spark, taking into consideration that you have replaced the coil and pack, visually inspect the stator closely to see if there are any portions of it whereas a sticky looking substance is dripping down upon the powerhead area. If so, that would result in a AC voltage drop to the powerpack capacitor which in turn would result in weak, errratic, and eventually no ignition/spark.

Should you encounter this dripping scenario, replace the stator regardless of what readings you may obtain.

I assume you have a water cooled regulator/rectifier assembly, and if so, here's a sure proof method of checking it "IF" your tachometer should be acting up. However, and unfortunately, you need to get the engine running first.

(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Normally the Gray wire leading from the tachometer is attached at the terminal strip to another Gray wire which leads from the water cooled voltage regulator/rectifier...... remove the gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.

1992 Johnson 40 hp-no start

Did what you said and spark was fine. What do I set as spark plug gap width?Is there a certain type of spark plug that is best?
I have Champion J17LM plugs now.
There is no oozing around stator. The coil has fire.
I have RPM gauge but no tachometer.
What next?

I asked in my post...."Does this engine have the warning setup with lights and gauges that function when you turn the key on?"....... You didn't answer it.

You have spark with the wire removed from the ignition switch... indicates the switch is shorted... replace it.

A tachometer is a rpm gauge.

I don't know what s/plugs that engine requires... check your manual.

1992 Johnson 40 hp-no start

No warning or indicator lights with this boat. I found the right spark plugs and gap needed. Will get a new ignition switch. Thanks for all of your help. It is
really appreciated. Will post update once I get switch installed,