Yamaha Oil Tank Float Switch.

[3rd Day]

I'm having an intermittent issue with the float switch in the engine mounted oil tank. On 3 occasions the switch has not cut off the transfer pump causing the tank to overfill and dump the excess oil into the airbox (like it's suppose to) thus causing a reduction in power, high oil consumption and making the Starboard engine work harder, use more fuel & oil to stay on plane. Stopping the boat and unplugging the switch harness will stop the flow and the problem goes away for a while. I have removed the switch, cleaned it and looked for obvious issues. Don't see any. Before I spend $160 for a float switch should I look at anything else? Thanks in advance. Brooks

 

[seasick]

You didn't say what year and model motor. Older ones have a control unit that could be bad.
Of course, the float sensor could be bad or stuck. Have you taken it out and tested it.
The manual overide switch could be activating on its own, either a bad switch or shorted connection

 

[3rd Day]

Thanks seasick. The motors are 1993 150's mechanically & cosmetically in VGC. Compression readings are at nearly new specs. I'm thinking about swapping the float switches from port to starboard and see if the problem moves. The trouble is it won't do it every time. I've pulled the float out, cleaned and inspected it. Harness connections are clean and tight. This is a simple switch: up it's off, down it's on. I suppose I could read thru with an ohm meter to determine if the magnet if acting on the center rod. The water tanks in Firetrucks use a similar setup to indicate tank levels. The further up the water is, the more lights it illuminates for the pump operator. When the float is lifted, the tach gives low oil warning and the transfer pump cuts on. Push the assembly back down and it stops. That's why I say it's an intermittent issue. Thanks for your interest. Tight Lines.

 

[seasick]

There are three 'switches' on the sensor. The highest tells the pump to stop, the middle tells the pump to start, and the bottom tells the motor to alarm and revert to safe mode.
So if you remove the sensor and turn on the ignition, with the flaot down, the alarm should indicate and the pump should start.
If you slide the float all the way up, the pump should stop. Make sure that the sliding float is not binding on the shaft.
Switching the senders is a good idea to help isolate the issue.
Good luck

 

[3rd Day]

Thanks seasick. The alarm works at the bottom & the pump runs then cuts off at the top. I just can't make it fail everytime. Thanks again. More to follow.

 

[BobP]

Get rid of it.

There's a lot of oil action in tank and vibration when motor is on and boat is in motion, so to me "sticking' is never a possibility. Then at rest, it should never work. It's easy to simulate at work, just drain tank down with ignition off, turn ignition on and watch it full and stop or not.

If you are sure no other circuit offenders, replace it.

Intermittant problems are always the pimple on the ass that doesn't go away and only gets worse.

 

[3rd Day]

I hear ya Bobp. No way to simulate the vibrations and such sitting static. I've got a test procedure to try with my ohm meter and then it's off to my local Grady dealer who has one in stock with my name on it. Thanks for the interest. Tight Lines. Brooks