Mercury pro xs 115hp

I have the same motor with about 25 hours no issues. I would check spark plugs, Spark wires, and coil packs first.

Not sure on your newer Opti but mine when I first turn the key on I have to wait a few seconds as there is a self test that runs. If I do not wait it will run like crap until I shut it off and wait for the self test restart it runs perfect. One issue I have had with mine is bad spark plugs even brand new ones bad right out of the box. Is it still under warranty if so I woul find a good Merc mechanic and get it in. One very important thing with the Optis it being a tight clearance engine DO NOT put the throttle down hard until the engine is warm.

They reckon it was a foweld up bottom sparkplug but it doesnt make sense from a fuel injected motor under 100 hrs with perfect comp.

its not that unusual to fowl a plug in that motor,cheap oil,ethanol gas,prolonged idling,etc.will do it in short order.
remember also that the bottom cylinder receives cooling water before the rest of the cylinders so it tends to run a bit cooler as a result and most often will be the first cylinder to foul a plug.

put good non oxy gas in it,make sure you are running the right oil,take it out,warm it up good and put it through its paces.

Todd Benjamin Milde wrote:

They reckon it was a foweld up bottom sparkplug but it doesnt make sense from a fuel injected motor under 100 hrs with perfect comp.

Reason it could be fowled is a bad plug as I stated above I have had brand new plugs be bad. My Opti is a 2000 and it has never seen anything but 10% oxy and Amsoil HP. Besides the bad plugs only other is water pumps every 2 years. Opti`s are bad about water pumps they do not last long.

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