Thread: Mercury outboard problem.

Mercury Marine Smartcraft and Guardian System Warning Horn Alarms | PerfProTech.com

I was thinking along the problem Cane Pole was having on Page 7 but he did not have the warning with his motor that was 30 HP Merc -- sounds like a Sensor

Originally Posted by Fish on Line

I was thinking along the problem Cane Pole was having on Page 7 but he did not have the warning with his motor that was 30 HP Merc -- sounds like a Sensor

I just disconnected the overheat sensor, that wasnt it I dont guess

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Brad, this sounds like you might have a electronics problem. Something getting hot and starting to break down after you run it a bit. I would suggest taking it to someone with a reader to diagnose. If it is you can chase your tail for days trying to figure it out. I don’t suggest this lightly because I’m about fixing anything you can yourself.

Originally Posted by Cray

Brad, this sounds like you might have a electronics problem. Something getting hot and starting to break down after you run it a bit. I would suggest taking it to someone with a reader to diagnose. If it is you can chase your tail for days trying to figure it out. I don’t suggest this lightly because I’m about fixing anything you can yourself.

Sadly i'm beginning to think this is what I'm gonna wind up having to do. I'm very good at fixing things if I know what's wrong. Thanks for the advice.

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Sounds as though the motor is going into safe mode. Get it scanned to see what faults have been recorded. Those motors have a history of collecting debris behind the thermostat and overheating.

Crappiepappy's post on the Guardian System at the Bottom could be of a big help if you Have a Tach === Oil Pressure sensor - engine runs at 10 % ,, reduction of 90% Batt Voltage - 75% of max === Coolant Sensor - Limited to 50% == Engine Speed sensor ,, exceeding 6200 cuts the spark to #2 and #3 cylinders & if there are plug connectors in the wiring harness it might be a bad connection Looking at the wiring Diagrams there is a Relay in the system that looks like it controls the Power Pac but I am thinking like Cray that something is breaking down electrically in the Guardian system but the RPM on the Tach will show what part is giving the Error

Pull the lower unit off and check the impeller!

Had a very similar issue with a friend of mines Mercury. It ended up being a rouge High heat alarm because it was getting a lack of water due to a dirty screen located behind the impeller on this model. Despite the dealership saying they had installed a new impeller, I found this to NOT be the case. His motor would go in to "limp" mode after a certain period of time. Although it appeared that water was streaming just fine, it was actually not the case.

Although his was a much larger motor and a 2 stroke, it was of the same year class. If memory serves me, they had issues/recalls on the coil packs as well. I would start with the impeller though as it could actually be overheating. If not, I would also look at the thermostate.