Hello all,

I have a 2007 115 mercury optimax outboard. It has recently been giving a 4 beep alarm with a couple minutes between, then 4 more beeps.

My investigating has found a low oil problem, I filled the tank. It was about half full. No fix

I then pulled the tank off the motor and checked the sensor for continuity, had 0 ohms of resistance.

For fun I put a jumper wire in the sensor plug that goes to the ecu and the beep remains.

I checked for water in the fuel, nothing. Cleaned the fuel filter housing. Unplugged the water in fuel sensor and still beeps

I am at a loss of what to do now. "Local" shop wants $100 to just hook it up and see why it's beeping. The troubleshooting guide says low oil or water in fuel.

Any suggestions are appreciated. I'm not afraid to turn wrenches either

Thanks.

Former Mercury dealer here. Take the oil cap off, turn the key you should get the low oil signal, now slide the float up to the cap. Beeping should stop. Could be a bad cap if it doesn't, start there. Caps are pretty cheap. Why did the oil get low ?

Check your feed tank, if it is using the double hose maybe you've lost pressurization and therefore not feeding the motor tank.

This engine model doesn't use a auxiliary tank from the boat. All the oil is stored in a tank in front of the engine under the cowling.

It was about half full when I filled it. Probably had over a gallon in it before I added any.

I should clarify that I have removed the oil tank and put a jumper wire in the sensor plug to bypass the sensor and the problem remains.

I also unpluged the water in fuel sensor and the problem remains.

Alright,

I think I may of fixed it. I started tracing wires today and found the water in fuel sensor wire rubbing on the VST. I was rubbed bare and probably grounding out. I ran the boat on muffs and had no beeping. I will take it for a sea trial and see what happens

Congrats on a DIY repair!  Testing the oil tank sensor (if you ever need to troubleshoot again)

is easy. Remove the little Phillips head screw and washer that's next to the low oil sensor and remove it from tank.

Hook multimeter to it set for continuity. Pass a small magnet up and down the sensor. Continuity beeper should sound

on and off as you move the magnet up and down the sensor.

If this checks out OK, then the little float inside the tank is either stuck in the down position or it has lost

it's magnetism and needs replacing. Problem with that is, you have to buy the entire tank as the float assembly

is sonically welded into the tank and is not serviceable by itself. Thanks Merc.

ETA -- Oh, the four beeps thing is a "non critical" alarm meaning the engine will run normally, but you need to have it checked out

as soon as practical. A solid alarm beeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeep is a critical alarm, like an overheat.

That means stop engine as soon as it's safe to do so. This alarm will also put the engine in "Guardian" mode limiting it's

RPM.

ETA2 LOL -- The WIF and low oil sensors work off of ground, meaning by jumping the oil sensor wires together you grounded

the warning circuit setting off the alarm. The WIF sensor only uses one wire because it picks up ground through the filter

casing through water conductivity.

Every forum I found troubleshooting the low oil, everyone said to put a jumper wire in the plug and if the sensor or float is bad, it will stop beeping. I measured the volts in the plug going to the sensor and got 5 volts when connected to the negative on the battery. A closed circuit on the sensor (normal condition) would mean 5 volts back into the ecu.

My WIF sensor also has two wires going to it. The sensor has two prongs about 1/4" apart inside the fuel filter housing.

Hmmm. Ok, I probably should have looked at the schematic before I wrote the above. I was going from memory of Merc products in general

which use a ground to trigger the alarm.

Funny thing, I just troubleshot an older Merc 225hp EFI oil tank last week and it was the grounding type sensor.

Sorry for answering without looking at the schematic.

Took the boat out for a test drive today. All seems to be running well and no more pesky alarm beeping in my ears! Finally after months of beeping, I can cruise in silence.