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Discussion Starter · #1 ·
This year - the last 2 times out, I have had the warning alarms on my motors sound.

1st time out this year; the stb motor alarm would beep very intermittently 1 to 1 1/2 times, then be silenced. Happened about 3 or 4 times.

2nd (last) time out. Ran HARD on the 1st leg of a poker run. After coming off plane this time after a few minutes, both motor alarms sounded and they stayed on for a while!

On the 575's mefi 3 the alarm will sound for:
Low oil pressure
Low Drive oil
engine over heating
low voltage

Each time this happened, I checked all gauges. Everything is fine. Drive oil is fine. Checked every engine sensor connection while alarms were sounding - all fine. (at least I checked the ones I could reach)

This alarm ONLY happens a few minutes AFTER I have come off plane. Turn key off then back on to restart, alarm will resound after a few seconds.
Since all gauges were fine, I came back up on plane, both alarms were silenced about 10 - 15 seconds after throttling up. The alarms came back on next time I came off plane, but eventually silenced after a few minutes. Then ran boat all day (on & off plane) and they never sounded again.

Are there different sensors for gauges and different sensors for ECU?

The only thing different from last year - I removed everything from the motor box and refinished and replaced JUST ABOUT everything in the motor box. Replaced anything slightly questionable.

Any ideas on what could be causing the alarm?

Thanks in advance for all responses.
 

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BillR said:
This year - the last 2 times out, I have had the warning alarms on my motors sound.

1st time out this year; the stb motor alarm would beep very intermittently 1 to 1 1/2 times, then be silenced. Happened about 3 or 4 times.

2nd (last) time out. Ran HARD on the 1st leg of a poker run. After coming off plane this time after a few minutes, both motor alarms sounded and they stayed on for a while!

On the 575's mefi 3 the alarm will sound for:
Low oil pressure
Low Drive oil
engine over heating
low voltage

Each time this happened, I checked all gauges. Everything is fine. Drive oil is fine. Checked every engine sensor connection while alarms were sounding - all fine. (at least I checked the ones I could reach)

This alarm ONLY happens a few minutes AFTER I have come off plane. Turn key off then back on to restart, alarm will resound after a few seconds.
Since all gauges were fine, I came back up on plane, both alarms were silenced about 10 - 15 seconds after throttling up. The alarms came back on next time I came off plane, but eventually silenced after a few minutes. Then ran boat all day (on & off plane) and they never sounded again.

Are there different sensors for gauges and different sensors for ECU?

The only thing different from last year - I removed everything from the motor box and refinished and replaced JUST ABOUT everything in the motor box. Replaced anything slightly questionable.

Any ideas on what could be causing the alarm?

Thanks in advance for all responses.
Could it be detonation causing the alarm?, it seems as though I read something about this in Hot Boat a few months back in the [email protected], I believe it was on a 600sci
 

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Discussion Starter · #4 ·
Fume detector is separate stand alone unit.
It is raw water cooled - plenty of water pressure and all water temps are normal.


The 575SCi is MEFI3 and is very basic compared to 600SCi. Thus detonation alarm is not possible,
 

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You should have 2 oil presure senders,,, one for the guage,,, the other is for the alarm.

Wonder if its on its way out
 

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I had this problem last year. Spent a ton of money trying to track it down. Intermittent, showing up as all sorts of weird signals to the ECU, most frequently the knock sensor, sometimes fuel flow, etc.

Finally, had both engine wiring harnesses replaced: Mercury can provide the exactly right ones given the serial numbers on the engines. Just carefully unplug the old, plug in the new.

The old harnesses had a tremendous amount of corrosion, in all sorts of different places. This causes the signals from sensors to ECU, and from ECU top actuators, to be screwed up and noisy.

Works like new now.
 

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I would be very shocked if you found any corrosion on Bill's boat. He is probably fuming at the mere suggestion. ;)

It is in better than new condition, no exaggeration.
 

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Discussion Starter · #8 ·
Not Right said:
I would be very shocked if you found any corrosion on Bill's boat. He is probably fuming at the mere suggestion. ;)

It is in better than new condition, no exaggeration.
Thanks! There isn't any.

Going to check the "oil pressure switch" which is located next to the oil pressure sender. Maybe a loose connection or bad switch. . . . . .
 

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We had the same problems with 382 Formula's. Ended up being X dimension was a little high and the steps in boat would aerate the water coming off plane and drives with side water pickups would suck air and set alarm. Same thing get on plane and would go away instantly. We ended up putting plugs in top holes of inlet on inboard side of drives.
 
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