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2001 70 Hp Johnson Losing Top Cylinder

C

captb

Contributing Member
So, when you first crank the motor and then intermittly afterwards, I lose power to the top cylinder. Have moved the coil packs around to see if one was bad, have moved plug wires with the same thought. Haven't changed spark plugs yet, but I guess they could be it too. Its always the top, even when moving the above around. When it loses power, I pull the plug wire and nothing happens. If I pull any of the other ones, the motor dies.

Problem comes and goes, almost always at first.

Either way, what should I check next? What's next in line after the coil pack?

Thanks, B
 
First of all you need to be sure whether your top cylinder misses spark or fuel. Connect a timing light to the top spark plug and watch the flashes when the problem comes and goes.

If you really lose spark, swap #1 and #2 spark plug first (btw how do they look like?). Then you should suspect the power pack and/or timer base. You can measure the timer base resistace with a simple multimeter, but you need a peak reading voltmeter (DVA) to continue troubleshooting.
CDI has a good troubleshooting guide here:
http://issuu.com/cdielectronics/doc...t.xml&backgroundColor=000000&showFlipBtn=true
The newer 3-cyl engines are on pages 41 and 42.

Do a compression test, just to be sure that the cylinder is mechanically sound.
 
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