2001 225efi 3.0 Mercury overheating alarm

[jgo5099]

I have a 2001 225efi 3.0 that has the overheat alarm going off. Due to the age of it I took it to Chris Carson and had the power head rebuilt and the lower unit inspected and a new water impeller. I got the motor back and after a few minutes running I still get a solid alarm and will not turn over 3000 rpm. I replaced the water temp sensor in the head but same issue. I checked the head temperature it was 164 degrees. Any ideas?

[OnPad]

Thermostats, injectors, oil starvation, or blocked water passage?

[jgo5099]

Chris Carson Marine disassembled the engine, bored the block, cleaned injectors, new water pump, new temp sensor I removed the oil pump and mix my fuel. When the alarm went off I checked the head temp with a lazer and it was only 164 degrees. I had this issue last time out on the water before I even sent it in for the rebuild. Thanks,

[OnPad]

So.... is this at all speeds?
What's the lake temp?
Do you have good water pressure, and gauge?
Not over propped?
Checked your stats in hot water for proper operation?


I'm not a 3.0l expert, but do have a old worn out one.
It doesn't run that warm in my climate, unless your plowing water. I have had the overheat alarm go off, with stuck thermostats, or a short warm up period. My alarm goes off probably closer to 180°, on a factory sender.

I think that about your vintage, mercury started putting water pressure sensors in their bigger outboards. These can be problematic, and put you in guardian mode. Also air in the oil pump would not be good.

Here's a link for some sort of newer horn layout, etc.
https://www.manualslib.com/manual/1737733/Mercury-225-Efi.html?page=168

[sonicss33]

Give Chris a call. I’m sure he will try to steer you in the right direction for a solution. Maybe not your intention but this thread sounds like you think Chris did you wrong. I find that hard to believe.

[Aaronhl]

Is it a constant beep or intermittent? If you removed the oil stuff youll have to ground out the sensor that goes to the tank on the engine...might have water in the water filter setting the alarm off too...

[Aaronhl]

My bad I re-read your first post and you said solid alarm - seems ECU related if it limiting the rpms - I am trying to figure out why mine has an intermittent beep

[Aaronhl]

9. Engine will not run over 3000 RPM and is notoverheating- Defective Engine Temperature Sensor.- Defective Throttle Position Sensor.- Defective ECM.

Possible Cause Corrective ActionEngine overheat sensor If horn sounds a continuous signal, the engine overheat sensor may be faulty. Disconnect overheat sensor and turn ignition key to “ON”position. If horn stillsounds a continuous signal, the ECM is faulty. Replace ECM and re-test. If signal does not sound,then engine overheat sensor is faulty. Replace andre-test.

[aj5099]

I called Chris Carson and left him multiple emails. They refused to answer so I think I was going pretty dirty.

[jgo5099]

I found out the exhaust tuner had two broken bolts and the others had came loose and the adapter fell down, I contacted Chris Carson he said it must have fell off the day after I picked it up from being rebuilt. Anyone had this issue before?

[OnPad]

Yes, with a 2.5L.
Aircraft bolts, and safety wire keeps it from happening again.