Mercury 90 Hp 3 Cylinder Engine now running on all three cylinders

.This motor came in and would not even turn over. It had been sitting for an extended period of time, but was to have at least started sometime this season.Diagnostic showed that the solenoid was faulty. Pulled the bad one and replaced, now it would turn over to do a diagnostic. Compression was 155,155 and 160.
Spark check showed no spark on #1, and fair spark on #2 and #3. DVA to #1 showed 4 volts and it takes at least 150 to fire the coils. Trigger DVA was 4+ x 3 which was within normal limits. Stator DVA was 40+ on the low side and 175+ on the high side which is within normal limits. Readings show a faulty pack. Prepared to change pack but the wiring was slightly rusted, so did some cleaning and fire returned to #1. Redid the DVA and now had right at 230 on all three. Checked fire and it was great on all cylinders. On to the fuel- fuel in the tank was stale and contained water. Drained the tank. Put the motor on our tank and tried to run. It was only running on the #2 cylinder. I was preparing to build the carbs, but decided to do a quick flush since the gas was pretty bad. After flushing carbs it picked up #1 and #3 cylinders. Now it would run on #1, #2 or #3. Water pump seemed to be putting out a pretty healthy stream.

This was another "I just bought it" so before going to much further it is time for fresh gas in the tank and a lake test. That will at least show that there are no problems with the lower unit gears, clutch and prop.



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