1998 EFI 200 HP MERCURY

[drmarke]

I know this is the Yamaha Web Site... But I've had good intelligent answers before. Please read over as I haven't gotten any help on the Mercury Web Site

I have three beeps when I turn on the key, and then the alarm goes off (proper testing at start-up). After I start the boat I get a pulsing alarm almost immediately indicating an Oil Alarm.
I have checked the oil to the engine mounted oil tank and it is full as well as the reservior tank. The cap of the engine mounted tank has a sensor which I have checked by checking for continuity (none) with the cap on and full continuity with the cap removed (simulating an empty tank). I tried to check the rotational sensor without sucess, but I tried a "used replacement" and had the same problem. I've hooked up a remote fuel tank with a 50:1 oil mixture and ran the motor with the oil line disconnected at 1500 RPM and got the proper 9cc of oil output and raised the oil arm (simulating wide oped throttle) and got 20cc of oil which is what the manual states is correct. I checked the voltage on the purple wire comimg from the terminal and it was showing full voltage. I went ahead at this point and and replaced the $240 oil warning module. Disgusted, I still have the same alarm! I do not see any wires that look to be shorted and I have a good ground throughout.
My best guess is it's still the oil pump rotational sensor (which several people have told me never go bad), the magnet on the oil pump shaft, or something simple like a horn malfuntion or the ignititon switch. The motor runs fine.
Please someone read this lenghthy posting and help!
Mark

[drmarke]

Someone on the other web site suggested that I disconnect the wires one by one to try to isolate the problem ... which I have done and will report here as well.

I tried disconnecting the sensors and checking if the alarm would stop. I first disconnected the blue/white wire (oil cap) no change. Next I disconnected the blue wire from the rotational sensor (no change) then the white wire from rotational sensor (no change). I believe the green wire is from the 2nd cylinder and I did not disconnect it, but it looks fine (not grounded). I think the brown/white wire sends the signal to the alarm and I checked at the horn for a grounded circuit and there was not that problem. The purple wire provides the power and when I disconnected it, the horn (and warning horn at start-up) stops. I checked all the ground wires and they are intact and well grounded.

[Ken]

'marke,
What about the temp sensors - should be one mounted in each head, if it is like the Yamaha.
Try disconnecting them one at a time to see if the alarm stops - could be a bad sensor.
Good luck [img]smile.gif[/img] ,
Ken K

[mbx4rr]

hi ' speaking fron french guiana
in the oil tank in the engine you have a float whit a magnet stuck under and it get unstuck so you have a low oil warning eving when evering thing is full and working ok ,the only thing to do is replace the oil tank it connot be fix