Re: 1990 Evinrude 200 hp, VRO removed, fouling plugs
rebranger..... Stick with the recommended Champion QL77JC4 plugs, gapped at either .040 or .030 .
Plugs usually foul either due to excess oil or weak spark... assuming that the compression is somewhere around 100 psi and fairly even on all cylinders.
I'd suggest you check the spark. With all the spark plugs removed and using a spark tester with the gap set to 7/16" for the spark to jump, at cranking speed the spark should be a strong blue lightning like flame... a real SNAP! Does it? If not, there is a possibilty that the stator is failing (melting down) which would result in a AC voltage drop to the powerpack capacitor.
Another cause of failing ignition/spark would be a slight intermittent short in the ignition switch which would allow voltage to access the black/yellow (kill circuit) of the powerpack.
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(Spark Tester - Home Made)
(J. Reeves)
You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:
A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.
Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:
..........X1..........X2
.................X..(grd)
..........X3..........X4
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Voltage To Powerpack Failures
(Magneto Capacitance Discharge Systems)
(J. Reeves)
The usual cause of having those type powerpacks fail repeatedly is having a very small of voltage applied to the Black/Yellow wire (Kill Circuit) at the pack. Test as follows.
Disconnect the Black/Yellow wire at the powerpack.
Insert either a ampere meter or a volt meter set to its lowest DC voltage reading between that Black Yellow wire and ground.
With the ignition key in the OFF position, observe the meter reading. Now turn the ignition key to the ON position and again observe the meter reading.
Any reading, movement of the meter needle, even a microvolt, would indicate that battery voltage is being applied to that Black/Yellow wire. If a reading is present, remove the other end of that Black/Yellow from the raised terminal of the ignition switch.
If the reading ceases to exist when the Black/Yellow wire is removed from the ignition switch, replace the switch. If the reading continues to exist, there would be a short of some kind in either the engine or instrument wiring harness.... to determine which, simply unplug the large RED electrical plug at the engine which would eliminate the instrument cable.
Note that the black/yellow wire must not have any other wire attached to it for the following reason!
Keep in mind that any accessory that has 12 volts running to it, especially when turned on, will have voltage flowing thru it and trailering out thru its black ground wire to complete the circuit. If that accessory has it's black ground wire attached to the "M" terminal that the black/yellow wire is attached to.... you will have voltage flowing directly to the powerpack.