Mercruiser Engine Alarm

jemccollum

New Member
Jul 29, 2015
5
Knoxville, TN
Boat Info
290 Sundancer 2001
Engines
Mercruiser 5.7 EFI w/ Bravo III
I have a 2001 Sundancer 290 (Bravo III). I have been getting a frustrating engine alarm. Sometimes it occurs at low speeds, sometimes when on plane, or even sitting in the slip. Sometimes when getting it while in the slip, putting the boat in neutral and revving the RPMs up a bit will cause it to temporarily go away (if it is sounding constantly) seeming to indicate with the engine revved up and full water flow it might slightly cool the engine and silence the alarm. Sometimes the alarm is intermittent and there is just a very brief blip other times it will stay on until turning off the starboard engine and restarting.

The boat runs smoothly. I have had a mechanic look at it and we have replaced the impellers, thermostat, and temp sensor and he has hooked it to a the computer and gets a code 14 ECT Cold and 15 ECT Hot error code. He suspects the cold error code is from when he took the thermostat out to test it and let it run so it pumped the full unrestricted water flow to the engine keeping it cool. He has tested the engine temperature and says it is fine and the manifold gets warm but not excessively hot to the touch and feels like the same temperature as the port engine. The gauges indicate the engine temperature stays below 170*. The oil pressure is normal, the alternator (voltage) gauge readout is normal and the drive fluid is full.

The mechanic thinks the computer could be bad, but before spending a lot of money replacing that suggested if it were him he would just cut the alarm wire so it doesn't buzz. He said he would watch the temp and oil pressure gauges closely and not spend the money on a faulty read out. I am reluctant to spend a few thousands dollars for a incorrect engine code when everything is working fine. Of course I am more motivated to not want to "blow up" the engine and have to replace it.

Any suggestions? This is frustrating and I am reluctant to just clip a wire to an alarm hoping it is wrong even though it appears to be running fine.
 
Water Pressure sensor (PSI) bad?

I just had t replace mine not sure your model year has one?
 
Has he also checked the pressures using a second set of gauges? I'm not sure how the alarm's work on our motors (we have the same boat, basically) but if the alarm is keying off the ECU and not the mechanical gauges maybe the oil press/temp/voltages/etc are in fact low or high and one of the gauges is not functioning correctly?

The other possibility is the drive res sensor is sporadic. We have alphas, but I believe it is a physical float and the merc manual says to clean it occasionally.
 
Look at page 68. Diagnostics-Without Scan ToolCode 14: Engine Coolant Temperature (ECT) Sensor Circuit (Non-Scan)
My money is on electrical issue. Put "boat" and "fix where the asterisks are (all together, 1 word).
http://www.*******.com/merc/servmanl/18/18d5r2.pdf
 
Last edited:
Follow up...

FWIW for anyone interested turned out to be a low pressure switch. New one ordered and being installed tomorrow which presumably will solve the problem, otherwise I'll report back.
 
Running into a similar issue with my 2015 260 sundancer 5.7 300HP. Replaced the sea water raw water pump and the water pressure sensor in the rear of the engine.
Runs beautifully between idle and 3200 RPM. At 3200 RPM, after about five minutes, engine fault code 25 appears on the electronic rpm gage. Temperature, oil pressure, and pump pressure appear to be normal. The water pressure sensor was replaced with OEM. I also have VesselView on line with water pressure shown.
Cheers,
Larry
 
Good morning,
I spent some more time researching other sensors that could take the place of the mercruiser sensor.
I found out that Mercruiser doesn't produce any parts for the power, as you already know, so I cruised around the web and stumbled onto other boat clubs that their members have the same issue. to make a long story short, the consensus was that a Delco/Remy Oil pressure switch will do the same job. So I ordered one from Amazon, of course, and it should be here on Wednesday. Twenty five dollars.
I also found out that there's a calibration problem with the sensor from Mercruiser, that's one of the reasons they fail. This one tech I was conversing with said that at ninety percent power will create problem if sensor is faulty.
Cheers,
Larry
 
Thanks, I'll check that out.

It looks different from the pics, the hex area compared to the npt. Mercs has an 1/8" npt. Let us know how it looks and works.
 
No worries...If you find something else or it's mis-information yet me know please. I'm going to physically check this sensor out before I install..
Cheers,
larry
 

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