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relax it's only life
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Discussion Starter · #1 ·
So the short of it 2004 6.2 liter mercruiser bravo xr drive. no probs except water pump last year. annual servicing. 72 hours. leaving marina water temp @ 150, oil @40psi, alternator out 12.8v. put the stick down rpm kick up to 4600 and the a buzzer. alarm continues till rpm drops then it goes on and off at different times. Take it to shop computer shows no faults. Cleared computer went out next day no probs. then day after no probs then at end of day alarm starts again @4800rpm and continues the 20 minutes back to marina. Engine goes into guardian mode and governs @3800 rpm all gauges stay in in good range and engine is warm but can touch all parts of it risers are cool. What do you think the problem could be ? I am going to change batteries already. All fluids are topped off. Any suggestions
 
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So the short of it 2004 6.2 liter mercruiser bravo xr drive. no probs except water pump last year. annual servicing. 72 hours. leaving marina water temp @ 150, oil @40psi, alternator out 12.8v. put the stick down rpm kick up to 4600 and the a buzzer. alarm continues till rpm drops then it goes on and off at different times. Take it to shop computer shows no faults. Cleared computer went out next day no probs. then day after no probs then at end of day alarm starts again @4800rpm and continues the 20 minutes back to marina. Engine goes into guardian mode and governs @3800 rpm all gauges stay in in good range and engine is warm but can touch all parts of it risers are cool. What do you think the problem could be ? I am going to change batteries already. All fluids are topped off. Any suggestions
Loose ignition wire.
 

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custom boat lover
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I also put this in your offshore teck thread.
You could try unpluging the too wires that go to the stern drive gear lube bottle mounted to the engine then wait about 60 seconds to see if the horn stops going off every 60 seconds. Then also the water pressure sensor might by picking up a bad reading some place, like low water psi, air bubbles, Or in some cases the water sensor it's self might be getting a bad ground and sending the ecm a out of range reading, try looking at the water sensor and see if you can see a lot of extra paint a round the sensor, And if you have some extra wire with you try touching the sensor it's self to a good ground on the engine. Why are you replacing the batteries? also make sure all the grounds are clean and tight on the engine and to the batt, If this don't work let us know and we can keep trying if you want to. good luck with it.:)
 

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relax it's only life
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Discussion Starter · #5 ·
i will check both those suggestions thank you other than putting the engine on the diagnostic computer is there another way to check the sensors because the computer did not show any sensor faults
 

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custom boat lover
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i will check both those suggestions thank you other than putting the engine on the diagnostic computer is there another way to check the sensors because the computer did not show any sensor faults
Not really, if you start unpluging all the main sensors now then it will show up next time you put a scan tool on it then some one might over look some thing that happend when it was really doing it.
 

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relax it's only life
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Discussion Starter · #7 ·
I was going to try the batteries to see if it was just a low voltage messin with the computer. They are four years old and probly ready anyways. So you are saying not to mess with the different sensors because it will mess with the diagnostic reading? the alarm was on constant all the way up from moabi to needls and the shut off when I was idling in the marina.
 

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custom boat lover
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I was going to try the batteries to see if it was just a low voltage messin with the computer. They are four years old and probly ready anyways. So you are saying not to mess with the different sensors because it will mess with the diagnostic reading? the alarm was on constant all the way up from moabi to needls and the shut off when I was idling in the marina.
It did not beep every 60 seconds when idling? Do you remember when the horn turned off as you where slowing down what rps it was? 1.8 psi is good but did it go up when reving it? When you put the new impeller in last year was the pump housing all groved up? yes if you play with the sensors now then the scan tool might show that only and you will not know what to look for later.
 

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relax it's only life
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Discussion Starter · #10 ·
the alarm stopped around 2000 rpm and did not go again. It is constant beep when active. The houseing was mild grooved and i wondered if the high rpm caused an low pressure activation at high rpm then it goes off at low rpm. but wouldnt i see this on the fault codes?
 

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the alarm stopped around 2000 rpm and did not go again. It is constant beep when active. The houseing was mild grooved and i wondered if the high rpm caused an low pressure activation at high rpm then it goes off at low rpm. but wouldnt i see this on the fault codes?
It sounds right and you might see it this time b/c you ran it for a longer time frame and it MIGHT show up. We use to call that a phantom beep b/c it never showed up on the tool
 

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relax it's only life
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Discussion Starter · #12 ·
I had it on the computer after the long run and it was still not showing anything I think I will try the batteries and then probably rebuild the waterpump with the r and r kit and see what it does. Thank you for all your help
 

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I had it on the computer after the long run and it was still not showing anything I think I will try the batteries and then probably rebuild the waterpump with the r and r kit and see what it does. Thank you for all your help
You might check the bolt that holds the shift linkage. My 6.2 was doing something similar to what you are saying and it ended up that bolt had vibrated loose and my alarm would go off at about 3000 RPM
 

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the alarm stopped around 2000 rpm and did not go again. It is constant beep when active. The houseing was mild grooved and i wondered if the high rpm caused an low pressure activation at high rpm then it goes off at low rpm. but wouldnt i see this on the fault codes?
Yes this will happen and not show up on the fault code. It will send it into guardain mode. Do the re-build on the H2O pump...
 

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relax it's only life
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Discussion Starter · #15 ·
thank you all for the help I am going to do and check all of these things one at a time this week and hopefully find the prob I will keep posting and let everyone know the outcome. Thank you all for your input.
 
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