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No Sparkb79 Johnson 100hp

L

lat67

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"I have a 1979 Johnson 100hp o

"I have a 1979 Johnson 100hp outboard motor and I have no spark at the spark plugs. Before I begin changing the coils, power packs, rectifier or stator I was hoping to get some help from this forum, which I have heard great things about.

1. As I understand it, the stator produces the electricity to the power pack, which go to the coils and then to the spark plugs. How can I tell if my stator is functioning properly? Can I use a continuity tester to see that current is coming from the stator? If so, how would I do this? If a continuity tester cannot be use, what then would I use to complete the testing?

2. Assuming that the stator test comes out positive, how can I tell if my power packs are functioning properly? Can I use a continuity tester to see that current is coming from each of the power packs? If so, how would I do this? If a continuity tester cannot be use, what then would I use to complete the testing?


3. Assuming that the power pack test comes out positive, how can I tell if my ignition coils are functioning properly? Can I use a continuity tester to see that current is coming from each of the power packs? If so, how would I do this? If a continuity tester cannot be use, what then would I use to complete the testing?

Thanks in advance for your help."
 
"Larry..... First, to keep it

"Larry..... First, to keep it simple, remove the spark plugs, disconnect the large RED electrical plug at the engine, then crank the engine to check the spark by using a small jumper wire from the battery side of the starter solenoid to small 3/8" nut that energizes the solenoid (not the 3/8" ground nut). Do you now have spark?"
 
"Hi Joe,

Thanks for the tes

"Hi Joe,

Thanks for the test procedure. I will conduct this test this afternoon (6/18/07) and report back to this forum.

Larry"
 
"Hi Joe, I just completed the

"Hi Joe, I just completed the test. I now have spark from three of the four cylinders. If you were standing in the back of the motor looking towards the bow, the cylinder to the top left has no spark.

As for the results of the test, I am guessing my problem is somewhere from the key switch to the female end of the main harness correct? How should I proceed now?

As for the cylinder not firing, I swapped a known working coil and determined that I have one bad coil....for $21/coil I will replace all four to be safe as I am unaware as to the age of the other three.

Let me know how to now determine what parts are no good.

Thanks,

Larry"
 
"Sounds good so far Larry. Aft

"Sounds good so far Larry. After installing the new coils and with the spark plugs still removed, test the spark again with that RED plug disconnected, and then with it connected.

If you have spark with it disconnected BUT no spark with it connected, leave it connected and move on up to the ignition switch.

Now at the switch, remove the Black/Yellow wire from the ignition switch terminal. With that wire disconnected AND with the RED electrical connector still connected, plugs still removed, test for spark by cranking the engine via the ignition switch.

If you still have spark, replace the ignition switch.

Hope that's not confusing. Let us know what you find."
 
"Hey Joe,

I will order the

"Hey Joe,

I will order the coils tomorrow (6/19/07) from marineengines.com. As I understand it, they will come from VT..I am in RI so I expect to get them but weeks end the latest. In the mean time because (with your help) I know where the problem is I will conduct the ignition switch test.......I will report back soon.

Thanks again........"
 
"Hi Joe,

Today, I took the

"Hi Joe,

Today, I took the black w/yellow stripe wire off the key switch and with the main harness connected, tested for spark and got spark.

This means that the stop circut has a fault, right? How do I now determine if the fault is in the key switch, blackw/yellow stripe wire or the shift switch.

Talk with you soon.

Larry"
 
"Assuming that you are crankin

"Assuming that you are cranking the engine sby turning the ignition switch to the START position and..........

You have NO spark when the black/yellow wire is connected to the "M" terminal of the ignition switch BUT do have spark with it disconnected, replace the ignition switch."
 
"Hi Joe,

I replaced the key

"Hi Joe,

I replaced the key switch. The motor fired up on the third shot. So to recap, I found one bad coil so I replace all four leaving me with 3 spares. Because they were inexpensive, I replaced the soleniod and rectifier. I've tested the replace ones and they are now spares. The starter, power packs and stator are all very good and working just fine. I am now looking forward to getting out on the water to do some flounder fishing. Thank you for all your help!!!!!!!!"
 
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