1973 Evinrude 18hp fastwin spark issue

[cathunter]

We put my motor in a barrel of water tonight to make sure it was going to run after doing a carb rebuild. Once we got the motor to start it would run fine for the most part but after about 15 minutes of running we shut it off and now im not getting any spark. It would do something similar last year while on the water. After letting it run for a while and shutting it off, it would not want to start back up for a few mintues. Could the condensors be getting hot not letting it spark or what? Im not knowledgable when it comes to boat motors so know nothing about it. Any help is greatly appreciated. Thanks, Josh

 

[64osby]

Re: 1973 Evinrude 18hp fastwin spark issue

Did you check to see if you were getting spark?

It sounds like the coils might be bad, pull the starter, remove the inspection plate on the flywheel. If the casing on the coils is cracked you need to replace them. If you do open it up replace the condensers and breakers (points) also.

Really bad coils look like this, but they still did spark.

 

[cathunter]

Re: 1973 Evinrude 18hp fastwin spark issue

At first we were getting spark and the motor would start up and run. Once we shut it off, it was no longer getting spark. We only checked the one cylinder though. Gonna do some more looking around tomorrow and planned on pulling the flywheel and putting new points and condensors on it anyhow so will check the coils as well. Is a crack the only way to tell if they are bad?

 

[kfa4303]

Re: 1973 Evinrude 18hp fastwin spark issue

Hi cathunter. Cracks are the tell tale sign that the coils are bad, but they may also have a frayed ground wire, or something less obvious. Virtually all of the original OMC coils failed over time. However, because your motor is a '73, it does NOT use the old, "universal" magneto system shown in the previous pic. Instead, I believe yours uses one of the transitional, "improved" ignitions they introduced in the early 70's. OMC went through a few different systems in the early 70's with varying degrees of success. I don't know much about them, but here's a link that may help. The good news is that I believe you can retrofit your motor with the old style magento, if you want. Keep us posted. Good luck.

http://www.sschapterpsa.com/ramblings/johnson_9.9_magneto.htm

 

[64osby]

Re: 1973 Evinrude 18hp fastwin spark issue

kfa - Thanks for the correction of information above. I am continuously learning here.

 

[scuba_redneck]

Re: 1973 Evinrude 18hp fastwin spark issue

Does this look like the magneto system under your flywheel? I have a '73 18 hp that I am working on right now also. It does not like to idle for a long time either. As soon as it warms up it wants to cut out. Right now my clutch dog and forward gear are in the shop getting the engagement surfaces re-faced. I replaced my points and condensers and it got better, but still not perfect. As I was setting my points, the wire coming out of the top coil (see picture #2) fell out of the coil. I looked into the hole where it should be and there was some nice green corrosion. As soon as I replace the wire and coil and get the gears back I will holler back with the news.

 

[scuba_redneck]

Re: 1973 Evinrude 18hp fastwin spark issue

 

[kfa4303]

Re: 1973 Evinrude 18hp fastwin spark issue

Hello again scuba. Because I have the old style ignition it looks like this, but you can see that your motor still uses the old armature plate and still has a place for a second coil under the flywheel. Also, these older motors don't have any "External" coils mounted on the engine block like yours. The entire ignition is the magneto and it's purely mechanical. Quite clever really. I wish I could answer you question about the loose wire, but it doesn't sound right/good. Any who, here's a pic of what the old style "universal" magneto looks like and an article espousing its many virtues. I'm sure someone else will have a more specific answer for you soon. Good luck. Keep us posted.




http://www.duckworksmagazine.com/03/r/columns/max/07/index.htm

 

[cathunter]

Re: 1973 Evinrude 18hp fastwin spark issue

Well I noticed two things tonight upon further inspection of the motor. Apparently I didnt pay real close attention to the title when I bought this motor bc ive been thinking this whole time it was a 73 when I found out tonight it is a 72. There are no external coils. Everything is under the flywheel. I also noticed that the flywheel key is broken. You can tell it has been cracked for awhile bc some of the break is dirty on both sides while the bottom is real shiny like it just finally broke all they way. Could this be the cause of losing spark and possibly throwing the timing off. Both coils look to be new with no wear and tear.

 

[AlTn]

Re: 1973 Evinrude 18hp fastwin spark issue

yes that key could be the issue