SabrToothSqrl

Trying to fix my engine alarm going off.
I now understand the engine has two oil 'sensors'.
One feeds the dash gauge - sender
One feeds the ECU - switch

I have MEFI3

Where is the one that feeds the ECU located? I think to test I pulled the wire off the wrong one.
The one that feeds the ECU is a switch. I'm told it's near the distributor.

thanks for any help!

I believe I'm looking for this guy: https://images-na.ssl-images-amazon....SR228,320_.jpg

oconnor marine

There is one on the port side of the block below cylinder 7 spark plug

SabrToothSqrl

Thanks, I think that's the sender for the gauge. That's the one I pulled as a test (alarm still going off), no effect.
I think now I'm looking for the switch one. I'm told it's near the distributor, but I'm stuck at work, and the boat's at home...

Blueabyss

I could be wrong about this , its been a while. But does it look like this? If so I think it has 2 wires that go to it. To bypass it unplugging it would do nothing. You would have to Jump the 2 wires.
. And it is on the port towards the back of engine close to #7

Chris

BUP

so you are following my advice ? The dollar blinky tool really does nothing I wanted to let you know in your other thread and have no idea where you found those fault codes in the link below ?

Need Help - Merc. 350 Alarm on when engine on.

BUP

You need to post your engine serial number to help with the correct set up and correct parts. The year of the hull means nothing. Merc has service Bulletins on the MEFI 3 350 especially the HO mag that might also be the issue.

SabrToothSqrl

Yes, you correctly determined that it could be the oil pressure switch.
However, I won't know for sure until I disconnect it tonight and start the engine.
The gauge shows correct oil pressure, so I don't believe it to actually be low.

In my previous troubleshooting, I was unaware that two oil sensor devices existed.
I did test (what I thought was) the oil pressure switch.
Turns out I most likely disconnected the sensor for the gauge, which would not impact the alarm.


The LED light test identified 2 DTCs, for which I replaced the sensors.
Cost of the tool was $0.00 as I had a 12v LED laying around.
I plan to test the port engine tonight to review any open DTCs.

Here is a relevant bulletin:
http://www.boatfix.com/merc/bullet/99/99_03.pdf

Here are the codes:
https://www.offshoreonly.com/forums/...mefi-codes.jpg

CodeMate User Guide (With codes)
http://www.rinda.com/acro/codemate.pdf

More MEFI info:
Pirate4x4.Com - The largest off roading and 4x4 website in the world.

Here are the STRB engine blink codes I received.
https://www.youtube.com/watch?v=XdLRhrTanxI&feature=youtu.be
14 & 23
Both sensors were replaced, codes cleared. Currently no codes show.

Tonight I will test by disconnecting the correct oil pressure switch.

STRB Serial: 0M047350

Thanks!

Man, do I hope it's just this $25 switch. Previous owner cut alarm wires on each engine. Vs. fixing it...
They also pretty much beat the rest of the boat as well. I've spent all winter making this thing whole, and could only test the engines since last week.

I do appreciate the help and offer, but I'm in PA... so that would be quite the haul.
I really did think I tried the oil pressure switch. I never realized the engine had two for oil and water. Cars (mostly) just have one sensor each, and the computer sends the data to the dash.
Why bother with two sensors? That's just more cost...

BUP

. Scan tool can guide one to fix it correctly currently and down the road. Inwhich down the road one will need if not currently. Like I said winky blinky is worthless for anything that requires more depth diagnostics rather changing sensors out - inwhich can lead to wasting time and money plus no water time sitting idle not fixed correctly.

You need to see parameters from the scan - key on and running, example the IAT temp while key on plus running, also voltage readings and that includes the 5 V reference readings as well from the scan tool. This really is why the winky blinky is not recommended.

SabrToothSqrl

Understood. I'm aware of the value of the Scan Tool, and will most likely one day purchase one. I do IT work for a living, and am a data nerd. If I'm unable to locate the source of the alarm, it will be in the near future. Here in PA, I still have another 2-4 weeks until the start of boating season. I'd like to get it fixed, but it's.. on a trailer and currently 50 and raining here. Not ideal boat time.

I have a mobile marine mechanic I've called as well, who has a scan tool.
However his rate is obviously more than $40 in sensors.

I made the mistake of testing against the wrong oil pressure device. I admit it. I'm human.
I didn't know the engine used two.
(Which I still think is stupid as it only adds cost and complexity, while not adding redundancy).
My full time job isn't marine engine repair. I do this for fun, save money, and I like learning.

If the scan tool was realistically priced, say $100 or even $200, I'd have one by now.
The barrier to entry is intentional, I get it, it's free market. If they can get it, good for them.

It would be great to see a scan-tool rental system, but I get that no one wants to risk loosing their investment.

BUP

I changed my post # 8 to maybe a better answer and I was throwing the other issues out in the mix for possible the wiring side that can effect sensor issues on top of -- I posted ( POSSIBLE ) open and short for 14 and 23 --- but now deleted it cause of the confusion on my part not being clear without writing a long post to explain that side of it. . . That was my mistake for the lack of info

Engine serial number helps with system set up and parts plus the location of installs. I understand what you are saying about asking where is the location for the switch ? Engine serial number will help with the exact location