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Boat Repair/motor runs like it is running on two cyl.

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QUESTION: I am working with a Mercury 4 stroke 2000 90 hp.  I run two bat. on the boat, Bat.1 for starting the motor and Bat.2 for accessories, they are hooked to a perko switch that reads 2 all 1 off.  The instructions said to never switch it to off with the motor running or you would damage the charging system, this was the only warning. The last time out I ran the #2 down very low and wanted to charge it up, so after we were under way I switched from Bat.1 to Bat.2 so it would charge it up, shortly afterward the motor started to run like shit, I switched it back to Bat.1 and it still runs like shit,like it is running on two cyl.  I have done this before without a problem, but never with the bat. so low, can this damage ?  The next day I used my timing light to check for spark, the motor starts easily and idles fine, but it seems like #2 and #3 don't have spark at idle, but off idle they fire fine.  This is the first Mercury I have owned and I have only put 20hrs on it since I got it, so I am not that familiar with it.  The way it ran coming in was like i had a fouled plug and dropped a cylinder... the plugs look good.  any thoughts?

ANSWER: sounds like you have a bad stator. it is under the flywheel and it can be checked with a peak voltage meter.or ohm meter to test for a short to ground...high side 130 ac volts or higher..low side 40 ac volts or higher..

---------- FOLLOW-UP ----------

QUESTION: so switching to battery two caused a problem with the stator and that is why two cylinders have no spark at idle but have spark off idle? I thought the purpose of the switch was to be able to charge both batteries by being able to choose which one the motor was running off of. did I miss something?

Answer
Ok the battery switch should not be moved while the engine is running because it could cause a problem with the charging system as it did with yours..  the stator is a part of the ignition and charging system of the engine..
the stator and regulator/rectifyer should also be checked..

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Everett Peacock

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Marine repair questions

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35 years experience boatmansbargains.com

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Taught Marine electronics at NOVA CC IN ALEXANDRIA VA

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certified, Yamaha outboards,yamaha stern drives, Mercury outboard, Mercruiser, Evinrude. Johnson, Mariner, suzuki, Volvo Penta, Honda,

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service exelence award ( yamaha)

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