Mercruiser 4,3 MPI from 2008, intermittent alarm after 3500 rpm??

[TheSwedishGuy]

Hi!

Need help with a Mercruiser 4,3 MPI from 2008. A strange intermittent alarm after 3500 rpm but gets silent again if I reduce the throttle (see video link below). I've installed new water pump and fuel pump, impeller and thermostat. I have checked the oil and gas filters, the ignition box, spark plugs and no water in the fuel.

I plugged in the computer and scanned for error codes, but nothing came up.

Any thoughts or clues would be much appreciated!

 

[Stinnett21]

Regardless of the alarm it doesn't sound like it's running very good. Seems to be missing. Intermittent alarms on MPIs are usually one permit minute I think. That sounds more like a chopped up continuous one.

 

[QBhoy]

That’s in a restricted mode. Need it plugged in. Or vessel view mobile

 

[alldodge]

Go to the shift plate and look for the in-gear switch. If its there, unplug it and the issue should go away

 

[Stinnett21]

Alldodge, just curious as I have an A1 G2, where does the OP go from here? Assuming something is amiss that's why it went into restrictive mode? The gear switch is needed correct? Is unplugging the gear switch simply to diagnose the issue?

 

[alldodge]

Alldodge, just curious as I have an A1 G2, where does the OP go from here? Assuming something is amiss that's why it went into restrictive mode? The gear switch is needed correct? Is unplugging the gear switch simply to diagnose the issue?

The gear switch IMO is useless and causes more problems then it would solve. Its one of those who in there right mind would rev a motor in neutral that high. If its disconnected nothing happens and the ECM doesn't care so to speak

 

[Stinnett21]

Its only purpose is to stop someone from revving it in neutral past 3500? So in the OP's case his has evidently malfunctioned (I realize we haven't heard back) telling the engine it's in neutral when it's obviously not. If this is correct (and there's no side effects) I will unplug mine and avoid this happening on July 4th w/end.

 

[TheSwedishGuy]

Thanks all for your thoughts! I'll try to unplug the in-gear switch and see if it works better. I'll revert back shortly.
Would a Vesselview mobile be valuable going forward or just waste of good money?

 

[alldodge]

No expert with VV, but it does need to connect on the CAN Bus of the motor. Being a 2008 (no serial number provided) it has a good possibility of being a 555 ECM. If so then would need to get and connect cabling to make it usable.

Might be easier to get Techmate Pro from Rinda. A scanner is always a good thing to have when problems arrive

https://www.rinda.com/marine/marinemenu.htm

 

[TheSwedishGuy]

The little plastic note on the side of the engine with all the data (incl serial number) is unreadable. But I have the socket labled Terminator, so VV should work right?

 

[alldodge]

Yes, just need the cabling

 

[TheSwedishGuy]

Here is a short video from today. I have replaced the IAC, the muffler and oil pressure sensor. But still the same alarm. :-(

I will also insert a new thermostat to see if the engine temperature is ok, now the engine is directly cooled, i.e. running without thermostat.

Link to video

 

[alldodge]

Was the gear switch unplugged?

 

[TheSwedishGuy]

Was the gear switch unplugged?

No, haven't tried that yet. Will do that during next week.

 

[QBhoy]

The little plastic note on the side of the engine with all the data (incl serial number) is unreadable. But I have the socket labled Terminator, so VV should work right?

View attachment 340209View attachment 340210

Yeah. That will work. All you need comes in the kit. You need to keep a hold of that yellow terminator cap, for the installation

 

[TheSwedishGuy]

Update. Replaced the oil pressure sensor, but still the same problem. :-(

But Vesselview reports lower oil pressure compared to the oil pressure on the front panel?

VV: 3500 rpm and 462 kPa (67 psi = 4,6 bar) BUT
Pannel: 3500 rpm and ca 6 bar (87 psi).

What could be problem here? What is "telling" the pannel indicator too high oil pressure and hence causing the alarm / guardian strategy?

 

[alldodge]

Are we still discussing an intermittent alarm or high oil pressure?

 

[TheSwedishGuy]

My guess is that the high oil pressure is causing the alarm?? Or do you think that the high oil pressure is something else?

 

[alldodge]

There are faults for Oil pressure open or short which then defaults to 50.7 psi and has a 2 beeps per minute

I'm not seeing an alarm going off for 67 psi, or even 87. It is a bit high for a stock motor seeing 87, but the ECM doesn't see the 87 or the 67 and I don't see an issue

Did you disconnect the gear switch?

 

[QBhoy]

Update. Replaced the oil pressure sensor, but still the same problem. :-(

But Vesselview reports lower oil pressure compared to the oil pressure on the front panel?

VV: 3500 rpm and 462 kPa (67 psi = 4,6 bar) BUT
Pannel: 3500 rpm and ca 6 bar (87 psi).

What could be problem here? What is "telling" the pannel indicator too high oil pressure and hence causing the alarm / guardian strategy?

Not sure there would be an alarm for high oil pressure. But that pressure recorded is ridiculously high. What’s the temperature reading at ? If it’s running cold with a full open thermostat, it could be that high perhaps.