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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3341
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a Yamaha osx150 saltwater series EFI. When motor is

Customer Question

I have a Yamaha osx150 saltwater series EFI. When motor is on plane works fine full speed. When I hit waves the motor rpms go down to zero and shuts off. I turn it back on it always starts. I replaced bulb, lower and upper mech pumps, filters, I don't think it's a fuel problem. I am stomped.
Submitted: 4 months ago.
Category: Boat
Expert:  Charles replied 4 months ago.

Hello, my name is***** will assist you.

The issue you are having is definatally electrical in nature. Start under the dash at the key switch and insect all wiring that is going to the engine for any loose wires. If you cannot locate any there, move to the engine and inspect all of the plug ins on the ECU and the plug where the wires come from the boat going to the engine. You should locate either a loose connection or a broken wire.

Customer: replied 4 months ago.
Charles just came back from the water and the boat was doing the same thing. However now it made a beeping sound like when the wrist band cut off near the key for the ignition. I got the boat out of the water pulled the two wires from the safety wrist cutoff. And it started right up strong. I am thinking as I hit rough water that kill switch moves around and cuts the motor off. I am going to try it on the water tommorrow. I checked every other wire, spark plugs etc.. Does this sound like a possibility?
Expert:  Charles replied 4 months ago.

Yes, that is a very good possibly that the switch is bad.

Customer: replied 4 months ago.
If it runs good tomorrow and I do not replace the kill switch will it affect anything else?
Expert:  Charles replied 4 months ago.

No. the switch is plug and play.

Customer: replied 4 months ago.
It wasn't that. I traced the wire all the way to engine. Found one wire connection that was loose and basically not connected. If I recall it was a yellow wire which I believe goes to the Cdi according to the service manual. Going out again in the water tomorrow to see how it runs on hole shot to plane.
Expert:  Charles replied 4 months ago.

The yellow wire would also do it. Any lose wire on the engine or in the dash can.

Customer: replied 4 months ago.
Put in the water for third time same thing. I give up. Took it to mechanic today he thinks it might be fuel injectors I hope not.
Expert:  Charles replied 4 months ago.

I dont think it would be the injectors, you are losing key power somehow.

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