75 evinrude 15hp spark trouble

[forgedin78]

Having trouble, only getting spark on one cylinder, so heres what I have done:

using spark tester by the way, I suspected a bad coil, so I switched the plugs where the coils plug into the wires coming from the ignition plate, then I had spark on the cylinder I lost it on before, and the one that was working didn't work now, so they switched. This told me that the problem wasn't in the coil, correct?

Next i took off the flywheel, everything is tight, and where it belongs, points are set right, so for the hell of it I switched condensers from one side to the other. No change

Then I started thinking maybe the wire is shorted, or partially broken where it leaves the timing plate, so i unhooked both ends, tested for continuity, tested good.

Then I switched the wires that go from the points, out of the timing plate, and to the external coils. I swapped them from one side to the other, put back together and tested for spark. have spark on opposite cylinder again, SO that tells me from the points down to the plug is good correct?

Now I am suspecting the driver coil, it seems to be the only thing left, other than points. Is it even possible for one side of it to go bad and not the other, I took it out and tested it for continuity, and it tested ok, but I don't know if that even tests anything...??

I guess I will have to swap the points from one side to the other, that seems to be the only thing I can think of that I haven't tried.

Is there a way to test the driver coil??

any other suggestions?

 

[Joe Reeves]

Re: 75 evinrude 15hp spark trouble

Clean the points with either lacquer thinner or acetone, then set them as follows.

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

Set the points as follows. Have the flywheel key aligned with the fiber rubbing 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.

Checking the driver coil.... yes there's a way to check that but I don't have my book in front of me at the moment. Temporarily run extended wires from the driver coil to the wrong set of points just as a test.... or as you suggest, switch the points but make sure they're clean and set properly.

 

[forgedin78]

Re: 75 evinrude 15hp spark trouble

Got my spark back, Not sure exactly what it was, but when I switched the points from side to side, cleaned and reset them everything was good, blue spark jumping 3/8. Not sure if they were just dirty or out of adjustment, but its on to the next problem lol

thanks

 

[F_R]

Re: 75 evinrude 15hp spark trouble

You are too fast for me. I was ready to tell you that it had to be the points, but you came back and reported it fixed.

The driver coil drives both external coils, so it couldn't be that.

 

[forgedin78]

Re: 75 evinrude 15hp spark trouble

Thanks for the help, I'm glad you still replied. It's good to know, if I have spark on one, the driver coil is good.

 

[OptsyEagle]

Re: 75 evinrude 15hp spark trouble

Points corrode and get dirty so cleaning was probably your solution. Your coil switch test was good except your conclusion was incorrect. Since the problem moved to the other cylinder it DID NOT rule out a bad coil but it did rule out the many other things that can kill a cylinder ... blown head gaskets, water in cylinder, crank case seals, a fouled spark plug, etc.

Just wanted to let you know for future reference.

 

[forgedin78]

Re: 75 evinrude 15hp spark trouble

Could you please explain why that doesn't rule out the bad coil in the original setup? Once I switched the coils, the plug that was not firing, was now firing, on the coil that I originally suspected was bad. Doesn't the fact that it now fires prove the coil good? By the way I'm talking about the two external coils only.

 

[Joe Reeves]

Re: 75 evinrude 15hp spark trouble

Forgedin..... You proved the coils are good. Sometimes it gets confusing.

 

[OptsyEagle]

Re: 75 evinrude 15hp spark trouble

Could you please explain why that doesn't rule out the bad coil in the original setup? Once I switched the coils, the plug that was not firing, was now firing, on the coil that I originally suspected was bad. Doesn't the fact that it now fires prove the coil good? By the way I'm talking about the two external coils only.

Well, let's say coil number one was bad and cylinder one was dead. You switched coil one to cylinder #2 and now cylinder number 2 is dead. How does it rule out that coil one is not dead? It doesn't, because if it was dead that is what would happen, the problem would switch to the other cylinder.

Remember, when you switch your coils you are also switching what point is being used as well, so that is why your problem moved to the other cylinder. In the end, your coil switch test just proved that it was ignition related, however, both your coil and point remained a suspect at that time, as well as condensers and perhaps some wiring, etc.

 

[forgedin78]

Re: 75 evinrude 15hp spark trouble

If you read my original post, I said that I switched the wires going to the coils, not the coils to a different cylinder. So, if coil one was bad, after switching the wires, cylinder one would still be down. Since it was not, coil one must be good.

 

[OptsyEagle]

Re: 75 evinrude 15hp spark trouble

If you read my original post, I said that I switched the wires going to the coils, not the coils to a different cylinder. So, if coil one was bad, after switching the wires, cylinder one would still be down. Since it was not, coil one must be good.

Did it run? It would seem to me that if all you did was switch the clips (if that is the wire you are talking about) without switching the boots to another cylinder, then you would be firing in the wrong position (piston at the bottom of the cycle and not top dead center) and the motor shouldn't run.

Am missing something here?

 

[Joe Reeves]

Re: 75 evinrude 15hp spark trouble

What "fogetin78" is saying is that cylinder #1 originally did not have any spark BUT after making the wiring switch, cylinder #1 did have spark, therefore the coil is okay. It was simply a coil test, not a modification to try run the engine in that manner (out of time).

 

[OptsyEagle]

Re: 75 evinrude 15hp spark trouble

Perhaps it's me but what wiring are we talking about? My understanding of this model is you have two points. Each point is set for each cylinder and their electrical wiring come out from under the flywheel to a clip. If you take a point that was set to fire when cylinder #1 was at top dead center (TDC) and now move its clip to the other coil of cylinder #2, it will be firing cylinder #2 when it is at bottom dead center. Will it not? Am I missing something here?

 

[OptsyEagle]

Re: 75 evinrude 15hp spark trouble

Ohhhh ... it was a spark test not a running test? Now I see. OK. Sorry for my slowness.

I thought he just changed the clips and fired the motor and for the life of me I could not see how his motor could run unless he changed the boots to the spark plugs as well.