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I have a 1997 75hp Mercury 2-stroke. This past weekend we went out about 8-10 miles. Bottom bumped all day started it up after about 4 hours of sitting and the alarm goes off. I checked the oil level in the oil tank andit was good, water pump was working great. it ran and sounded fine. The alarm will sound even if the key is turned to the'on' positionand the engine is not running. any ideas?
 

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Neptune calls me "Daddy"
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I think there are two reasons for the alarm.

1. Low oil pressure sensed

2. High Water temp sensed

If the engine runs fine and the oil pressure and water temp looks okay, it's one of two sensors.

Normally the alarm will soundwhen you turn the key "on" because i n fact the oil pressure is low. The pump is not running after all. The water temp should be low then too.

1. First, disconnect the oil pressure sensor at the block. (One wire)

2. Turn the key on... if the alarm goes off the overheat water temp sensoris bad. If the alarm does NOT go off it's the low oil pressure sensor.

Either should cost $30.00 or so

Jim

AMATUER mechanic...
 

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First off,2 strokes don't have oil pressure. Second, is the alarm pulsating or steady. Steady is Temp and can be from actually O/H, or bad sensor. Pulsating is caused by low oil level, sensor switch, magnetic floator oil warning amp. If have replaced several tanks beacuse of the bad float. I would be glad to look at it if you bring by the shop.
 

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Neptune calls me "Daddy"
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sosmarine (2/15/2010)First off,2 strokes don't have oil pressure. Second, is the alarm pulsating or steady. Steady is Temp and can be from actually O/H, or bad sensor. Pulsating is caused by low oil level, sensor switch, magnetic floator oil warning amp. If have replaced several tanks beacuse of the bad float. I would be glad to look at it if you bring by the shop.
I bow to the expert...:bowdown:bowdown:bowdown

Jim
 

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It is a steady alarm. I had it low on oil before and it did pulsate. It shut off as soon as I added oil. So it would be a safe guess that it would be a sensor since it goes off even when it's cold correct?
 

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If I am not mistaken, if your oil injection gear (not sure what the actual name is of this thing) that runs of the cam shaft is not turning, you will get a steady alarm as well. SOS will probably know if this is correct off the top of his head. BTW, these things have been know to go bad and cause some serious damage to your motor.
 

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That engine does not have an oil gear sensor, however the oil warning module can also cause a constant tone if it shorts out. It is easy to pinpoint if it is the problem. Find the wires from the oil tank coming out of the bottom of the tank. Follow them to the 2"x2" black square box. It is located just to the back of the tank and is near the bottom of the powerhead. Unplug the tan wire at the module. If the tone stops, then the module is shorted. If it were an intermittent tone you heard, then I would say to check the oil tank and sensor in it.
 

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Thanks for the help guys I had SOS take a look at it and it was the sensor for the oil level.It's on forfishing by the weekend. Thanks again to SOS. Quick service and a fair price.
 

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jim t (2/15/2010)I think there are two reasons for the alarm.

1. Low oil pressure sensed

2. High Water temp sensed

If the engine runs fine and the oil pressure and water temp looks okay, it's one of two sensors.

Normally the alarm will soundwhen you turn the key "on" because i n fact the oil pressure is low. The pump is not running after all. The water temp should be low then too.

1. First, disconnect the oil pressure sensor at the block. (One wire)

2. Turn the key on... if the alarm goes off the overheat water temp sensoris bad. If the alarm does NOT go off it's the low oil pressure sensor.

Either should cost $30.00 or so

Jim

AMATUER mechanic...
Jim T flies alot and stays at alot of Holiday Inns!!!! :doh

Thanks for trying though jim!!!!
 

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That engine does not have an oil gear sensor, however the oil warning module can also cause a constant tone if it shorts out. It is easy to pinpoint if it is the problem. Find the wires from the oil tank coming out of the bottom of the tank. Follow them to the 2"x2" black square box. It is located just to the back of the tank and is near the bottom of the powerhead. Unplug the tan wire at the module. If the tone stops, then the module is shorted. If it were an intermittent tone you heard, then I would say to check the oil tank and sensor in it.



This occoured to mine and with these steps found on the net or my manual (can't remember) I found out that my "2x2" black square module was bad.



good luck
 
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