Oil Alarm going off with '98 Yamaha ProV150 two stroke

AB-Indy

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Sep 14, 2021
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Just bought the boat. Took it out and it ran pretty good for a few days, then the alarm went off, and the power cut way back. I checked the main oil reservoir under the hatch, and it was about 1/2 full. This tank looks to be about 2 gallons. The reserve tank under the cowling is at the full mark. I filled the main oil tank back up, and every time I run the motor, after about 10 minutes the alarm still goes off. After looking in the manual, and not finding much, I saw the switch just below the reserve oil tank, so I held it up, and it pumped more oil into the reserve tank, which seems backwards to me. Any idea if there's something I'm doing wrong? Is it maybe a bad sensor? Or maybe the oil injection pump not working?

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AB-Indy

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main tank is on the motor, remote tank is in the hull
OK, got it. (Keep in mind that I have never owned an outboard motor before). So when the upper tank inside the cowling uses oil, does it automatically pump oil into the upper tank from the lower tank, to keep it at the right height? If the lower tank gets lower than 5 quarts, does the oil buzzer go off? The upper tank was full the whole time.

What else would make that buzzer go off? Water in the separator?
Bad oil pump?
 

boscoe99

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OK, got it. (Keep in mind that I have never owned an outboard motor before). So when the upper tank inside the cowling uses oil, does it automatically pump oil into the upper tank from the lower tank, to keep it at the right height? If the lower tank gets lower than 5 quarts, does the oil buzzer go off? The upper tank was full the whole time.

What else would make that buzzer go off? Water in the separator?
Bad oil pump?
When the main tank on the motor gets somewhat low it asks the computer for more oil to be sent from the remote tank in the boat. When the main tank gets filled it tells the computer to stop the transfer of oil. This happens over and over again without anyone being aware of it happening.

When the remote tank gets low on oil the automatic transfer will stop. Some tachometers have a caution light to tell the user that the remote tank is low on oil. If he fills up the remote tank the light goes out and life returns to normal. If the remote tank is not refilled, and the motor continues to be run, at some point the main tank will get very low. When this happens the warning horn will sound, the motor will go into the RPM reduction mode and if a Yamaha tachometer is in use a red warning light will appear.

Two things on a Yam will normally sound the alarm and put the motor into RPM reduction mode. Low oil in the main tank. And over temperature.
 

AB-Indy

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Got it. When the alarm went off, the Main tank was still full, but the remote tank was 1/2 full. After I filled the remote tank, the alarm still goes off after running for 10-15 minutes. A couple of days ago I replaced the impeller, so I'm pretty sure its not overheating. Tommorow I'll check exactly what the gauges are doing.
 

mike_i

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Could be the motor is over heating which also causes the same alarm and makes the motor go into limp mode.
 

AB-Indy

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Could be the motor is over heating which also causes the same alarm and makes the motor go into limp mode.
As I mentioned above, I replaced the impeller a few days ago, so unlikely it's overheating. Anything else that would make it overheat?

What are the chances the sensor is bad?
 

mike_i

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How are the thermostats? Has the main tank oil level changed at all? It should not be topped off all of the time, it should drop enough to see that it dropped before the pump turns on to fill it up from the sub tank. Don't worry about the toggel switch it's only used if the transfer pump isn't comming on as it should to transfer oil from the sub tank, most likely located in your bilege, to the main tank. The reason I'm thinking high temp is because the motor runs awhile before the alarm sounds and motor goes into limp mode. Are you able to run the motor at home? How is the water pressure from the pisser? what lights on the dash are turning red?
 

AB-Indy

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How are the thermostats? Has the main tank oil level changed at all? It should not be topped off all of the time, it should drop enough to see that it dropped before the pump turns on to fill it up from the sub tank. Don't worry about the toggel switch it's only used if the transfer pump isn't comming on as it should to transfer oil from the sub tank, most likely located in your bilege, to the main tank. The reason I'm thinking high temp is because the motor runs awhile before the alarm sounds and motor goes into limp mode. Are you able to run the motor at home? How is the water pressure from the pisser? what lights on the dash are turning red?
Well, not sure what I have for a thermostat. The first picture is the gauge before the alarm goes off. After about 5 minutes running, the alarm goes off, but the gauges look exactly the same, only the green light on. When I had it on the lake, the water pressure gauge read about 12psi. I changed the impeller, and have only ran it in the driveway with muffs since then. When running in the drivway with mufs, the water pressure gauge reads zero, no matter what rpm's I'm running it at. Is this normal? Should the water pressure gauge read if it's hooked up to a hose?:


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I know the lights work, because when I turn the key on before starting it, all three lights come on:

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I don't think it's overheating, because after the alarm goes off, I can place my hand on the block and leave it there without burning my hand.
 
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AB-Indy

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This may be unrelated, but maybe not??? Right now I have no power to the stereo or the nav lights, or the fish finder. Could that possibly be related? (BTW, those electrical items did work before. Not sure of the timing of when they lost power to when the alarm starting going off) could have been same time, could have been a day before.
 
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mike_i

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The no or low water pressure reading is normal, the system runs on high water volume at low pressure. Just make sure there is water coming from the pisser. Are you able to run the motor in a tank or trash can making sure the water level above the pump? It's been awhile since I had my 2 stroke 175 but I believe you should have two thermostats. Has the main tank remained completely full at all times or have you seen the level drop? Your new electrical issue "should not" have anything to do with your main problem, check for a blown fuse. Try to run the motor in a tank and let us know what happens. Post a picture of the back of the motor showing the spark plug side of the motor.
 
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