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  1. #1
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    '95 Johnson 175 Intermittent Alarm

    Took the boat out today...for the most part it ran well.
    Then out of nowhere I get an alarm @~4000RPM, not constant, no rhythm. Could not tell which motor was generating the alarm. Can't be low oil....disconnected those wires and both tanks are >1/2 full.
    Lowered to idle and alarm went away.....ran up to 4000 again......got an alarm again......did this a few times.
    Returned to the dock......
    Not over temp (not constant alarm), did not go to limp mode.....
    Could it be a fuel problem?
    Don't think it's too serious....at least I hope not, was still able to get to WOT!

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    #2
    I'm not a boat expert but there are several around here. I would think the vacuum switch would be a good place to start checking. Yes it could be a fuel problem.
    Someone lot smarter than me will be along shortly.

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    #3
    What/where is the vacuum switch?

  4. Member
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    #4
    The vacuum switch is on the fuel bracket, between carbs. Has a black and tan wire. This can set off the warning horn and indicates a fuel restriction.

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    #5
    Any way to test for it?

  6. Ohio Fishing Reports Moderator omcforever's Avatar
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    #6
    Chapter 2 of your OMC repair and service manual you have describes servicing and checking of it and your fuel system,,,May be a fuel problem and it is doing its job.
    Last edited by omcforever; 09-15-2019 at 11:22 PM.

    Age and treachery will always overcome youth and skill !!

  7. Ohio Fishing Reports Moderator omcforever's Avatar
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    #7
    Have you sorted out your other idling/fuel woes yet?

    Age and treachery will always overcome youth and skill !!

  8. "OVER THE LINE SMOKEY!" headhigh's Avatar
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    #8
    I just tested a OMC vacuum switch I have sitting here in the garage. It’s open until a vacuum is applied, then it’s shorted.
    1998 Ranger R93
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    "Life, liberty, and the pursuit of happiness."

  9. Member
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    #9
    Thanks for that answer about the vacuum switch. I've been asking that question in another thread. I thought that was how it worked but i couldn't get anyone to confirm.

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    #10
    Makes sense.......I need to check my fuel supply to see if I have any restrictions that would activate the switch.
    Haven't had a chance to do so.....being that my alarm was intermittent might not be too easy to find!!

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    #11
    Was thinking about this....if my alarm continues.....I can disconnect the wires to determine which engine it is coming from.

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    #12
    Yes that would work

  13. SC Club Moderator ChampioNman's Avatar
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    #13
    Quote Originally Posted by ajv00303 View Post
    Was thinking about this....if my alarm continues.....I can disconnect the wires to determine which engine it is coming from.
    Did you find the location of the vacuum switch yet? Can you verify that the alarm comes on over 4000 RPM? Running twins makes troubleshooting a little tougher, once you locate disconnect one of them and run the motor to speed, it will be a solid tone and will go away when you back off the throttle. A FACTORY service manual will point you in the right direction but you will need a tool that can pull vacuum.

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    #14
    Haven't run the boat since last week.
    When/if it happens again and I can repeat it I will disconnect one at a time to determine which one was doing it.
    It wasn't a constant alarm and was not cyclical like what I hear a no oil alarm sounds like. It was a quick beep then went off....

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    #15
    Sounds like it could be a bad low oil sensor in the oil tank. If your other tests don't prove positive, find at the motor and unplug the wire from the tank.

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    #16
    Quote Originally Posted by 316jughead View Post
    Sounds like it could be a bad low oil sensor in the oil tank. If your other tests don't prove positive, find at the motor and unplug the wire from the tank.
    Already disconnected the low oil sense wires as neither sender was working......

    So it seems to me my alarm can only be generated by;
    1) Overtemp: constant Alarm, limp mode
    2) No oil: Quick rapid 1 sec beeps
    3) Fuel restriction: constant beep, can operate at high revs

    In my case I think its #3 but intermittent.......I obviously need to confirm.

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    #17
    Have you tested the warning horns to see if they would stay on?

  18. Member
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    #18
    Quote Originally Posted by 316jughead View Post
    Have you tested the warning horns to see if they would stay on?
    Yes.....even replaced one that sounded weak.

  19. SC Club Moderator ChampioNman's Avatar
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    #19
    Quote Originally Posted by ajv00303 View Post
    Haven't run the boat since last week.
    When/if it happens again and I can repeat it I will disconnect one at a time to determine which one was doing it.
    It wasn't a constant alarm and was not cyclical like what I hear a no oil alarm sounds like. It was a quick beep then went off....
    When the keys are turned on you will get an initial beep on both motors.

  20. Member
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    #20
    Quote Originally Posted by ChampioNman View Post
    When the keys are turned on you will get an initial beep on both motors.
    That's correct.

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