Engine alarm beep

sparky90731

sparky90731

Member
Mar 27, 2016
88
los angeles
Boat Info
Good Day Sunshine - 2005 340 auto pilot, rib boat davit rear camera
Engines
Twin 8.1 horizons
2003 280 4.3mpi
one beep alarm going off intermittent, for one second rpms drop on starboard engine, no fault code coming up, mechanic changed cap rotor plug wires and went away for a couple weeks then changed oil and it came back. I checked float in drive bottle ok, unplugged and still get alarm, changed impellers, not sure what causing it but it sucks :huh::huh: any ideas ...
 
been there no fault codes popping up :huh:
 
You might need a more advanced code reader. But if the RPM's are dropping, then it's a critical issue (or at least the ECM thinks it is). Often times this can be due to a piece of dirt on the oil pressure sensor or a flaky sensor. Something like that.
 
thanks dennis, i had my local mercruiser guy come down and plug in laptop and no fault codes, but im thinking to replace the oil pressure switch next, thanks Roy
 
Hi do you have a part number for the oil pressure sender? Thx
 
sender is nothing more than a switch. It's either open or closed. Can be easily tested without replacing it.
 
There should definitely be a log in the computer's memory, especially if RPM's are dropping. Maybe your guy just didn't have the right scanner?

I always hate to replace things without verifying. But since you have twins, you could try swapping. The downside is they are a bit of a pain to get to. They're located where the oil filter would normally be on the block. I don't know the part number offhand, but any online Mercruiser parts place will work to get the part number. And, like mentioned above, very easy to check with a cheap DVM.

BUT... when the issue happened, what were your gauges reading? And, you're positive that you lost RPM? Run it again and check those things. Otherwise you might be on a wild goose chase, here. It could be something else (like low drive fluid), but we can only offer suggestions based on the info you provide and the "loss of RPM" is a major piece of info for me.
 
was the cap and rotor replaced with oem factory parts? or aftermarket. i had a problem similar to this on my last boat with an aftermarket cap and rotor
 
the gages were reading normal and when the beep goes off the rpms drop for 1 second. Its happened so many times I see the rpms drop off and then come back up. the only thing that is different between the 2 engines is that the starboard engine with the problem runs right above 170 and the port runs right below 170 degrees. I believe he installed oem parts. The drive fluid is good. thanks for the input cant wait to get this one behind me :smt101
 
Hi Did you have any luck resolving the beep issue?
I have a 06 340 same thing no codes
I just replace the engine start switch no luck still beeps
When I fire up port engine it will beep and also when running on plane both engines cut out for a secound
Any Ideas?
Thanks
David
 
I'm going down a similar path trying to diagnose the dreaded double beep every minute on one of my '02 8.1S Horizon inboards. Started doing the warning double beep Friday after sitting for a couple hours on the hook while everyone was swimming. When I started after sitting for a couple hours, got the double beep every minute or so. Had run fine earlier. Nothing else indicating a problem, oil, temp, voltage, RPM's all seem in line on both engines at idle and at speed. Fluid levels all good, strainers cleaned, just doesn't seem like there's a problem, but according to the Mercruiser Horn Warning System info sheet I found, the double beep apparently indicates sensors or an Open-short in circuits as probable cause, and there are about 3 dozen possible codes. (Maybe it's a failed, corroded, gunked up sensor that just "thinks" something is wrong, had that on the Jeep once.)

Not having a tool to read the codes, I brought the boat to the marina that my service team owns so one of their techs can go pull codes Monday. Fun fun fun... Gotta resolve this before the run to Block Island.
 
Do you guys have O2 sensors on your year engines?

I had the dam beeping (it seemed like every 30 seconds to a minute) on my 2011 260 Sundancer while running and it was the emissions related and it did show up on the ECU scan.

I have no clue when emissions systems were added to boats...... but it would be worth looking into.

Sea Ray covered the O2 replacement under some emission warranty that's longer then the over all boat warranty.
 
Little Ducky said:
Do you guys have O2 sensors on your year engines?

I had the dam beeping (it seemed like every 30 seconds to a minute) on my 2011 260 Sundancer while running and it was the emissions related and it did show up on the ECU scan.

I have no clue when emissions systems were added to boats...... but it would be worth looking into.

Sea Ray covered the O2 replacement under some emission warranty that's longer then the over all boat warranty.
Click to expand...

The 8.1S Horizon's have an IAC valve (Idle Air Control) which is one of the fault codes:

https://us.v-cdn.net/5020499/uploads/editor/m1/512au5re9znf.pdf

The tech that works on my motors said that the closed system cooling can be fine, but the sensor on the raw water side can get corroded and fault out. We'll see what the numbers show Monday I hope. Wish I had a scan tool.
 
One continuous intermittent beep shows as maybe the drive lube monitor on the fault charts. Did you mess with the floats in the bottle yet?
 
Siesta Key said:
Hi Did you have any luck resolving the beep issue?
I have a 06 340 same thing no codes
I just replace the engine start switch no luck still beeps
When I fire up port engine it will beep and also when running on plane both engines cut out for a secound
Any Ideas?
Thanks
David
Click to expand...
Siesta Key said:
Hi Did you have any luck resolving the beep issue?
I have a 06 340 same thing no codes
I just replace the engine start switch no luck still beeps
When I fire up port engine it will beep and also when running on plane both engines cut out for a secound
Any Ideas?
Thanks
David
Click to expand...

Did you ever solve this problem? My 06 340 will been and all gauges go to down for a split second. This happens at all RPM levels.
 
Jeff, I was having the same issue since I bought my boat last August. Single beep, rpm drop and almost instant recovery. Almost like you turn the engine off and then back on. This was happening randomly, infrequently, at first but it got worse and started happening regularly. Doing my own troubleshooting and searches for solutions came up empty. I let the marina have a go at it but they couldn't figure it out either. They said there were no codes being thrown as it was happening in real-time. Over the winter I did more research and came up with a possible cause- PCM. Now, I have a single so there was no way to swap PCMs to test, but you have twins. Try this, put the PCM from the problem motor on the good motor and test. DO NOT put the good-side PCM on the problem motor, you could fry a good PCM. In my case it was the PCM, so in case you haven't already do so, try that test and post your results.
 
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