TOPIC: 115 tower no spark all cylinders.

Short version of my tale of woe. Fired it up at home, ran great. Off for camping and relaxation. Arrive and launch at ramp and she fires right up and idles fine while I let it warm up. Shift into reverse and stalls. Fires right up again and I shift & quickly throttle up.Back away from the dock hit forward and almost no power.Almost like fuel issue. Tried adjusting carb air/fuel mixture screws with little effect,engine running. A couple times it finally powered up like it had cleared something for a few split seconds and then just plain quit and would not start again. Using a timing light on each cylinder I have no impulse on any plug wire.Is this an acceptable method to determine if I have spark?I am attaching diagrams of my particular engine and test procedures outlined in my Seloc manual(it's what I have for right now). Stator and trigger test seem to pass with the specs they list so am I looking at switch boxes? It has had them replaced some years ago by Billr with DCI units. I find it hard to believe that both would fail at the same time. Can anyone offer quick and dirty test to nail down the rotten component that nearly ruined our weekend. Thanks

Melanie
Note:I did not preform coil test since it would be unlikely they would all fail at one time.

My engine electronics

#1 = try disconnecting the Mercury Switch...

#2 = I would try a spark tester (imo) but this method to test should work too.

#3 = Check connections for corrosion

Almost sounds more like a bad ground or loose wire.

Thanks Matt. I should have included that I did disconnect the wire to the mercury switch with no change. I just got a reply Email from Thom who also thought a poor,corroded connection somewhere.

Thom had me remove the 2 black/yellow wires from the switch boxes and it fired right up.These tie into the mercury switch circuit. Now I need to trace the short.

Melanie

I have a 1962 Merc 700. Has 2 coils and 2 sets of points and condensor. 3 cycls work if one set has failed.

Mercury switch on the block set at an angle. this is the tilt switch to kill the engine if you hit something and it kicks up. sometimes on mine if it has been tilted up for some time the mercukry switch will not disengage. so I tilt it up a little ways and let it fall (Thump!! or two) it usually starts right up after that!!!

i recently had a problem with the ignition switch in a 80hp that grounded the ignition in the off and on position.