1971 Evinrude 40hp No Spark

[correspondant2003]

Hi,<br /><br />I've recently acquired a boat with a 71 Evinrude engine, 2 cylinders, 40 hp. The boat had not been used for 2 years, so I fully expected to have some problems... and I was right:<br /><br />The engine ran for about 15 minutes, no problem, just a bit rough at idle. I shutdown the engine, then started it to go again, but I was not able to get good power from it. Tried for 5 minutes, then shut it down again to make sure nothing was loose. Then, I never managed to start it again.<br /><br />I bought the Seloc repair manual for it, and checked the obvious things. It soon became quiet obvious that there were no sparks at both plugs, so I removed the hood and flywheel, and this is what I found:<br />the points look good, but perhaps not exactly at the right gap. I can adjust this.<br />I was mainly surprised to find that there is always a connection between both sides of each point, even when the point is opened. The way I understand it is that one side of the point is connected to the ground, while the other side is connected to the coil, the condenser, and a third wire (which I think is the kill wire).<br /><br />So, while the point was opened, I disconnected the condenser -> still there was continuity between both sides of the point.<br />I disconnected the kill wire -> still there was continuity.<br />I disconnected the coil wire: finally, no more continuity! Why is the coil grounding the point?<br /><br />I disconnected the coil wires, and check the ohms. 1.10 on one coil, 1.20 on the other. On the Seloc manual, it says that the measurement should be 1.40, +/- 5. But this is for the low-tension magneto model, while my model is the flywheel magneto. I paged through the whole manual to fond what should be correct measurement for a flywheel magneto coil, can't find it.<br /><br />So: does anyone have any idea what could be wrong with my engine? Why am I not getting any spark? Could it be something else? Perhaps I'm missing the point (no pun intended) altogether?<br /><br />Post your theories, opinions, don't hesitate, I'm running out of ideas.<br /><br />PS: I find it weird that the engine ran fine (or almost fine), lost some power, and after I shut it down, I did not get any sparks any more.

 

[correspondant2003]

Re: 1971 Evinrude 40hp No Spark

This is a follow-up to my engine problems.<br /><br />The answer is: DOH!<br /><br />How many times must we be told before we learn: on a two-stroke engine, before anything else: -change-the-plugs-.<br /><br />The plugs looked good, seemed clean, at the right gap... finally decided to put my engine back together after seeing that there was nothing wrong with the coils, only a small adjustment of the point gaps.<br /><br />Changed the plugs: vrrrroooommmmm!<br />Put back the old plugs: zip<br />Put back the new plugs: vrrrroooommmm!<br /><br />The lesson is: change the plugs, and keep a spare new set on boat.