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four beeps on 150 Mercury Optimax

Old 01-08-2013, 11:32 AM
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Default four beeps on 150 Mercury Optimax

Long story short… I got four beeps and turned the engine off. I found that the oil reservoir was bone dry but the engine mounted oil tank was still nearly full. I serviced the oil reservoir and still get the four beeps every few minutes. I read the owner’s manual –the instructions state to remove the cowl, remove the oil cap on engine mounted tank, run the engine at idle to fill the oil until overflow. I can’t recall exactly wording but it was something to that effect.

Does anyone know if this means that I should add oil through that fill cap or that running the engine at idle with the cap removed will cause it to fill from the reservoir ;?

Old 01-08-2013, 12:40 PM
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probably a bad sensor in your oil tank.
Old 01-08-2013, 01:04 PM
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Fill up the remote boat tank with oil. Start the engine, remove and then remove the little cap on the engine mounted oil reservoir. Wait until oil is right at the top and then put the little cap back on. This gets all of the air out of the lines. Cycle the key and your good to go.

Four beeps can also be water in fuel. On the VST tank under the hood, their is a water seperator. You need to replace each season as well.
Old 01-08-2013, 01:10 PM
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Your alarm is being tripped by the low oil sensor in the aux tank on the engine. (Edit: see below post, I forgot about water in fuel alarm)

Fill engine mounted tank through cap. Leave cap loose and start it up, crank case pressure should start oil flowing from reservoir... when it starts leaking out of engine mounted reservoir... tighten cap.

Once the aux tank is full and you still get the alarm, probably a bad oil lever sensor. You can pull the engine side of the harness and short it out with a wire.... if the alarm goes away, you have a bad sensor.

If the reservoir doesn't fill you have a problem, it could be:
-sludge in reservoir bottom
-stuck check valve in line between reservoir and tank on engine or obstruction in line somewhere in between the two tanks.
-leak in line from crankcase
-Loose cap on the Main reservoir or loose cap if you have a secondary fill for the main reservoir.
- Just so I don't get beat up..... no oil in the reservoir

Check those and get back to us.
Old 01-08-2013, 01:11 PM
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For future reference on warning horns. Thanks Capbone... forgot about water in fuel.

Old 01-08-2013, 04:30 PM
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since it appears most didn't read the post - yes without venting the onboard tank will stay low and trigger the alarm again, just crack it and it will fill then overflow, it will be fine then. The cap is air tight so the air can't get out, it will take a bit longer as the lines coming up are empty but will fill and overflow when all are full.
Old 01-08-2013, 04:35 PM
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The float on the aux oil tank cap is known to fail as well. That's what happened to me when I had an alarm that would go off with a full aux reservoir. Replaced the cap and it fixed the problem.
Old 01-09-2013, 06:27 AM
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Do it right,fill the remote tank,replace the cap tight and loosen the cap on the engine mounted tank.Allow the tank to fill from the remote and tighten the engine mounted tank cap.This verifies that the system is working like it should.
Old 01-09-2013, 08:53 AM
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If you still have the alarm after the above oil tank procedure you should take the two wires out of the tank assembly and make a jumper to fool the alarm and see it if stays off.
I had the exact same problem. 4 beeps every two minutes.
I had both oil tanks to the brim and put a new water separator on and still got the alarm.
Someone on here told me about fooling the computer with the jumper wires to see if the onboard oil tank sensor was bad. Tried that and found it was indeed the oil tank sensor. I bought a new tank and sensor assembly and everything is good to go.
Good luck.
Old 01-08-2014, 07:27 PM
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Just got this 2003 Mercury 150DFI & had a similar problem with the 4 beeps......First fill your remote tank.....then tun the engine on & open the cap on the engine tank too bleed & fill the tank "it should overflow so get some rags". you may want to turn the engine on/off a couple of times. If all works & you still get 4 beeps than you want to check if the sensor in the reservoir tank is good just follow & disconnect the wires & put a jumper cable to unite the ones going to the ECM. If the beeping turns off the float/sensor in the tank is N/G theres no repairs here you must replace the hole tank. I was curious so I cut my tank open & the float had a magnet that dislodged/unglued from the bottom, so essentially the sealed tank is not serviceable. You can get the same 4-beeps if you have water in the fuel filter it has a sensor at the bottom.
Old 01-08-2014, 07:37 PM
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As stated above, let it make a mess over the on-engine oil tank. Then tighten the cheesy cap on the cheesy on-engine oil tank and it should go away. If the cheesy cap leaks you'll need a whole new cheesy aux tank.

I gave up on Merc making the Opti a real engine, instead of a half-assed mod to the old Merc EFI block with a bunch of cheap, inaccessible harnesses and auxiliaries on it. Talk about piss-poor engineering. Never again....
Old 05-17-2017, 02:46 PM
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my reservoir has been getting about one inch low and throwing the code after about one hour of use. I hooked a pressure test to the tank and the cap leaks. my question is that if the cap leaks shouldn't the tank be overflowing not letting air in?

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