79 15hp Johnson. Spark tester broke coil???

[Canwalleye]

This is going from bad to worse. My 73 rude is down so I had to borrow a friends Johnson. Now it will not work. It would start up find, I would push the choke knob in once it was going then head down river. Well then every 100yards it would die. I would pull till my friggen arms hurt and get it going again, it would run for another 100 yards. Eventuallyit would run without problems. Yesterday I bought a spark tester for my 73 Evinrude sport twin. I tried it on the 73 and no spark jump. Then I though just so I could see what this spark looked like I would try it on the Johnson 15 hp I borrowed. It sparked once brilliant blue and then nothing. Now I cant even get the plugs to spark. Any ideas?

 

[liz873]

Re: 79 15hp Johnson. Spark tester broke coil???

This is going from bad to worse. My 73 rude is down so I had to borrow a friends Johnson. Now it will not work. It would start up find, I would push the choke knob in once it was going then head down river. Well then every 100yards it would die. I would pull till my friggen arms hurt and get it going again, it would run for another 100 yards. Eventuallyit would run without problems. Yesterday I bought a spark tester for my 73 Evinrude sport twin. I tried it on the 73 and no spark jump. Then I though just so I could see what this spark looked like I would try it on the Johnson 15 hp I borrowed. It sparked once brilliant blue and then nothing. Now I cant even get the plugs to spark. Any ideas?

Spark testers are good but doesnt specifically tackle one issue. They test entire system points, condensors, coil etc... So if theres no spark it can be caused by several things. For my 72 johnson i checked the coils resistance using ohm meter. I believe you can do the same. If your coils are on their way out they will start and run but die when the engine heats up. They cool a little and you can start up again.

 

[F_R]

Re: 79 15hp Johnson. Spark tester broke coil???

So, what year is the 15 Johnson?

Anyhoo, how wide a gap is the spark tester set? Or does it even fire across an air gap? It may be looking for more spark power than the motors are capable of producing. A '73 should jump a 1/4" open air sharp pointed gap. A more modern motor will jump a half inch with ease.

 

[JDusza]

Re: 79 15hp Johnson. Spark tester broke coil???

So, the Johnson ..... can it run at full or half choke?
Make sure the spark tester is well grounded.
Not real sure you have an ignition problem ...

 

[Canwalleye]

Re: 79 15hp Johnson. Spark tester broke coil???

It jumped the spark tester once (SE setting on the tester), then after a few hundred more pulls, NOTHING! I ordered a CDI, I should have tested the coils first! It starts up fine at the boat landing then starts dying after a few hundred yards.

 

[OptsyEagle]

Re: 79 15hp Johnson. Spark tester broke coil???

It starts up fine at the boat landing then starts dying after a few hundred yards.

That is usually not a spark issue. If it didn't spark you would not make it a few hundred yards. Have you tried pumping the primer bulb just as it is starting to die? It sounds to me that you are have a fuel pumping issue.