1976 650 no spark

[larrybowman]

Took my boat out yesterday and, after 3-4 hours of fun, it died on me in the water at full throttle. Tried quite awhile to start it, even using starting fluid, but all to no avail, it just would not hit at all. After getting towed back to the boat launch and bringing it home I tested it and I am getting no spark on all three cylinders.

It's a 1976, serial number 4386563. It has no distributor, but rather 3 coil packs.

I have done extensive work on automobile engines and such, but I know very little about 2 cycle engines.

I've searched online quite a bit, but all the wiring diagrams I can find show a distributor rather than coil packs.

can anyone help me in diagnosing this no spark problem?

 

[Gus71]

Hi!
Try the Merc 700 70hp. They startet in 76 or 77 and had 3cyl coil igition. As I recall the 3 coil system was half of the towers (6 cyl) But its sone years since I worked on those
Working on 2 strokes is not so difficult and you dont have to think of valves and cammshaft.
Good luck on your 650!

Gus

 

[JDRains]

I had same issue of no fire found the timing belt had broke.

 

[GA_Boater]

No timing belt on this one. It uses a trigger for timing spark.

Try this wiring diagram - https://maxrules.com/oldmercs/Wiring/1966ona/70.jpg

 

[larrybowman]

No timing belt on this one. It uses a trigger for timing spark.

Try this wiring diagram - https://maxrules.com/oldmercs/Wiring/1966ona/70.jpg

Now, that looks more like my motor.

So, I was told that the blue wire going from the stator to the top of the switch box should have 100V AC when cranking over. Mine only has around 30-40V AC. So, does that indicate a bad stator?

 

[GA_Boater]

Now, that looks more like my motor.

So, I was told that the blue wire going from the stator to the top of the switch box should have 100V AC when cranking over. Mine only has around 30-40V AC. So, does that indicate a bad stator?

That's one of the things manuals are for - Troubleshooting all kinds of problems.

 

[larrybowman]

So, I should purchase the manual?