Constant alarm above 4000RPM

laureniac1

Last year I got a constant alarm the day before I put the boat away I was running just a little over 4000RPM. My 2005 270 went into “guardian” mode and engine automatically throttled down to 1800RPM. Mechanic pulled code this year before I launched and said it was low voltage so we replaced both batteries. Of course went out yesterday boat was running great for about 10 mind and the alarm started again. Boat went back into guardian mode. Called mechanic back he said he will put it back on computer. Any thoughts? Thanks 

zaverin1

Ahh
low voltage could be your alternator/ charge system/ cables etc 

Spyderweb

I had similar problem with 2007 350 Horizon, started last day of season a year ago.  They replaced the impeller and it was good for about a month the next season.  Another place looked at it, checked water pump,for scoring, saw none but replaced the impeller again since they had it apart.  Good for about a month then did it again.  End of the season original place looked at it and said code said it was low water pressure in water pump above a certain rpm. I believe they are replacing the water pump this spring. I'll know in a few weeks if it fixed it.

Black_Diamond

Go for the Hardin Marine water pump if you are replacing. 

laureniac1

All great feedback thanks everyone 

LaRea

Definitely could be insufficient cooling water.  Bravo 3?  Check the fitting where the raw water comes from the outdrive through the transom.  The fitting corrodes and restricts water flow.  @Spyderweb - same for you.  Doesn't matter how good your pump is if there's not enough water getting to the pump.

The fitting can be checked from inside the boat.  Replacing it is an out-of-water experience.  

laureniac1

 Bravo 3 I will check thanks La Rea

Wildboating

Typical mechanic, replaced parts with no diagnostics to determine why you had low voltage.  Get your Check book warmed up. 

LaRea

One thing you can do is remove the supply hose from the back of the water pump.  Water should come gushing in.  If it's only a trickle, there's your sign.

laureniac1

Thanks again everyone for the feedback- Alswagg where is the 70amp breaker located?

laureniac1

Thanks All

LaRea

Here's the thread from my cooling issue a while back.  Same symptoms as you are experiencing.  

http://rinkerboats.vanillaforums.com/discussion/1945/solved-engine-alarm-on-merc-496

laureniac1

LaRea that is such valuable information- I will pass it for sure!  Thanks SO much 

davidbrooks

Definitely check the code.  Low voltage is a very different set of issues than low water pressure.  Dont forget to actually verify what the voltage is.  Just because a sensor says it is low voltage doesn't mean it actually is low.  The sensors go bad also.

rasbury

I was not really having any over heat issues but I have a thru hull and the bravo III pick up tube- when I tore it down for another issue, man that was really restricted. Not sure I really understand why at that point it does but as I've read here and elsewhere, a common problem. I was always running a "little warm" so will be anxious to see if the temp comes down just a tad- I'm fresh water cooled and understand that these engines run a little hotter and even have a different thermostat.

laureniac1

Mechanic came down on Friday. Pulled the code and alternator not putting out correct voltage- new one on order 

laureniac1

Update!! After new batteries and alternator boat still alarmed with an over rev code.  The battery cable to the starter was loose! Not an easy find because mechanic bumped it by accident and boat shut off . The morale check connections because I sure did not 

randy56

Wow at least you have new batteries and alt. 

Michael T

Great news! We have discussed checking all connections to related trouble sources, particularly grounds, on this forum quite a few times but a good idea to remind ourselves of this!