1992 mercury blackmax 150 only #4 cylinder has spark

kevo526

Recruit
Joined
Aug 23, 2013
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5
I have a 21ft proline with a mercury black max 150. 2 to 3 weeks ago and my motor died out on me while we were out fishing. On the way to the fishing hole a big wave launched me and had a rough landing. After the wave we got to the spot fished for a couple hours. On the way back in I noticed the engine didn't want to plane. Seemed as if there was no power in the motor. After 10 to 15min, I took the cover off and noticed one of the coils came off a plug. So I plugged it back in and attempted to start it again. All I hear now when I try to turn it over is the starter engaging into the flywheel then falls back down after 1 sec and all you hear is the starter cranking. Had to get another boater to pull me back to the boat ramp. Since then it hasn't started. Tried to flush the engine and failed.

When I got back onland I replaced the spark plugs and and tested the coils. Only #4 cyclinder sparks. Checked the coil packs and they are good by hooking each coil pack to the wires with current. Checked the volts and noticed there is alot of resistance in that one cylinder coil pack. None of the other cylinders don't have any current. I know its an electrical problem.

This is my first boat and I'm still learning to troubleshoot the engine. Im not good with wires running to a motor. Me and a friend who is more mechanically inclined went through the manual trying the different tests and ruling out the possibilities. If anyone had had this happen to them or have an idea what's going please let me know.
 
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