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  1. #1
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    250xs beeping from low voltage

    My motor keeps beeping at me for low voltage. It seems the volts show around 14 until I start to reach top speed and then it starts dropping and eventually starts to beep when it drops just below 12. I'm wandering what would be causing this. Sometimes it runs fine and doesn't move at all but usually does lately. When I hit the trim, it drops pretty quick no matter how fast I'm going. Does this sound like either the belt is slipping or maybe a voltage regulator? Oh, and when the volts remain high around 14, my speed is much faster than when it drops. It seems sometimes the engine runs strong and sometimes pretty weak and it's hard to even get to 60. It's got a brand new alternator on it as well. Yesterday in a tournament, the volts actually stayed just above 12 and kept creeping down below and I would let up on the gas and it would stay at 12 but not any higher. Something ain't right. Thanks for any help.

    Texas Hawgs Bass Fishing Guide Service
    2018 Phoenix 21 PHX - 2018 Mercury ProXS 250



  2. Member
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    #2

    Re: 250xs beeping from low voltage (texashawgs)

    Check for water leaks on the powerhead spraying onto the alternator at high rpms. You may not be able to physically see water but look for dried limescale on powerhead near or under the alternator area

  3. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #3

    Re: 250xs beeping from low voltage (ssimpala71)

    Also- check your battery cable connections AT THE BATTERY, and at the engine itself. Make sure they are clean and WRENCH TIGHT (no wingnuts).

    LOAD TEST the battery to confirm that it ACTUALLY WILL produce 800 CCA or higher. Pay no attention to the stickers on the battery- we want to know what the battery ACTUALLY PRODUCES!

    Additionally, check the output cable lug (large red cable) on the alternator and confirm that it is SNUG.

    Loose connections at ANY of the above will cause your complaint.



    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  4. Member
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    #4

    Re: 250xs beeping from low voltage (EuropeanAM)

    All connections were tightened by wrench and are really tight. hmm. Really making me wonder now. Thanks for your guys input. Guess I'll have to start saving and bring it to someone that works on these motors a lot.

    Texas Hawgs Bass Fishing Guide Service
    2018 Phoenix 21 PHX - 2018 Mercury ProXS 250



  5. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #5

    Re: 250xs beeping from low voltage (texashawgs)

    If you want to check your alternator... I just set these directions out for someone else today (same would apply to your engine):

    Starting point for diagnosis involves removing the large red lead from the alternator (DISCONNECT BATTERY FIRST).

    Isolate the red lead so that it cannot "arc" to anything metal, then reconnect battery.

    Check to ensure you have 12VDC on the red lead with it disconnected from the alternator. If so... you have a connection between the alternator and the battery (a path for charging current to travel).

    Next, start the engine and allow it to idle. Check the voltage on the LARGE OUTPUT TERMINAL of the alternator (with the wire still disconnected). You should see 20-27VDC. Also jumper a test lead from the metal case of the alternator to a known good ground... see if it changes your results. If not, shut the engine down and proceed to:

    With the key on, engine off, check voltage at the red and the purple wires in the small connector. You should have 12VDC on both wires.

    If all above tests "pass"... disconnect battery, and remove the alternator. It's bad...

    BTW... don't forget to check the battery cable connections AT THE ENGINE. Tight isn't necessarily "Good". Actually remove and inspect- or better yet, LOAD TEST the system directly on the "battery cable lug" of the starter, with the ground of the load tester connected to the starter body itself.



    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  6. Member
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    #6

    Re: 250xs beeping from low voltage (EuropeanAM)

    Yesterday I noticed that the cover that goes over all the wheels driven by the belt had the seal that slides over the top of the air compressor loose and pushed in. I reinserted the seal and made sure it fit in right when replacing that cover. Today I took out some clients and the voltage seemed to stay just a pinch above 14. Kinda weird but awesome. I also noticed that oil reservoir was not filling and I started to get a low oil warning. I took the cover off and ran the engine a little while and when it still wasn't filling I shook the oil tank and it started filling once again. When I checked the end of the intake nozzle inside the tank it was clean. Something must be in there. hmm.

    And the last thing is my hydraulic jack quit and I can't move my engine up to get max top end. It does ride good in rough water but 65 ain't getting in at the start of tournaments. Any ideas how I can move the TH Marine Jack up at all? I tried jumping off just the 2 wires and it won't move. It's only an '05 model. hmm.

    Thanks guys...

    Texas Hawgs Bass Fishing Guide Service
    2018 Phoenix 21 PHX - 2018 Mercury ProXS 250



  7. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #7

    Re: 250xs beeping from low voltage (texashawgs)

    Voltage- keep and eye on it. Of course... double check your battery connections, make sure they're clean and tight, engine cable lug installed FIRST, then the remaining ones "largest to smallest"... finishing off with a stainless locknut (no wingnuts used on these motors).

    Oil tank filling... if you're down 3/4"... you "tapping" on the oil tank probably had nothing to do with it. It takes a minute or two to build enough pressure in the system to push oil up (especially if there is air in the oil line). Keep an eye on this... if it occurs again, you may have a leak. Most common cause is a loose cap on the boat oil tank (or remote oil fill if you have one). This would include removing the cap, and leaving it off for a period of time while you go to the store to get oil...

    Jackplate- sounds like the motor is bad. That's going to be tough to address without the motor being replaced. If it's the two wire motor (no separate ground wire)... connect leads from motor directly to battery (one to positive, one to negative). Should run one way- reverse leads, should run the other way.



    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

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