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2.2 Mercury 1987 No spark

rfinkel

Member
1987 Mercury 2.2 purchased with sailboat.
I was told that it wasn't used for 4 years.
I cleaned carb, changed gas, changed gear oil, water pump impellor and spark plug.
(The motor parts seem very clean but there is rust in the spark plug boot. an the exterior metal portion of the original spark plug was rusty.)
I pulled the starter rope repeatedly and the motor didn't even sputter.
I took the motor off the boat and checked for spark against the engine block.
I have no spark at the spark plug or spark plug boot.

How can I check for the source of the problem without replacing each ignition component one by one?
 
That model has an "ancient" ignition system so start with a couple simple tests - you will need an ohm meter.

Start by testing the spark plug wire - should have almost no resistance (total continuity) at all from one end to the other.

Then you can test the ignition coil. Set the ohm meter to X1 ohms. Remove the black/white wire from the spark plug coil. The red probe goes to that "disconnected" black/white wire, the black probe to ground (any convenient spot on the powerhead itself) - you should get about 1.5 ohms of resistance - more than that = a toasted primary coil "under" the flywheel.


Then test the spark plug coil. Put the red probe on the post where that black/white wire was connected and the black probe to ground. You should get between .81 and 1.09 ohms resistance (meter still set to X1 ohms).

If all the above tests ok then hook it all back up and finally check as follows - meter set to X1 ohms - red probe into the sparkplug boot (at the end where the sparkplug would connect), black probe to ground. Should see 4.25 - 5.75 ohms (give or take a little - the temperature can skew the numbers a little).

If that final test is ok then you need to replace the points/condenser under the flywheel...
 
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