Problems with MasterCraft Riding Mower. Please help!!

[mattperkins]

Hello,

I have an old Mastercraft mower than I am trying to fix in my free time. My brother got it from someone and just tossed it aside. The bad part is that it looks like someone has tampered with the wiring and/or tried to bypass some things. So here are some problems with it:

-Will start and continue to run with no weight in the seat.
-Surging sound when running. I can also see the headlight getting brighter and lower with the surging of the engine.
-The battery doesn't last long. It's a new battery. I can jump start the mower with a car battery and I can charge the battery, but it will die very quickly. I checked the voltage across the battery and it reads 12v with the mower off and still 12v when the mower is running.

Any ideas where I can start?

This mower looks nearly identical to mine.

 

[Buckshot 1]

:smile: Gives us the model number of the tractor and the engine numbers. Then maybe we can help you out with your problem. Don B.

 

[timtractor]

Your seat ? , Someone bypassed the two wires going to the seat. More likely there is a short jump wire connecting the two or they are just disconnected. The wires could always be reconnected to the sensor again.

Running ? , I would say that the carb needs to be cleaned. The galloping is usually cased be a dirty or plugged air adjust port.

Battery ? , I think you should take the battery back to where you got it and have them test it. It sounds like you might have a defective battery.

 

[mattperkins]

Okay, I suspect that the charging system is bad. I don't much much about riding mowers, though. :/ The engine is a Briggs and Stratton 12.5hp. Model no. 289707. I believe the model no. for the mower is 1183AC. The sticker on the mower advertises 14hp so I believe someone put a different engine in at some point.