225 oil light comes on, motor goes into limp mode.

Slippery · Jan 2, 2006

Hi I have searched for a couple of days however have not found quite this error surfacing. I do note though that the first thing I should do when I return the boat is put 50 to 1 mix in the tank before I go any further. I have a Mercury 225 Black Max 3.0 Litre Oil injection outboard around 10 years old, original fit on a 23" Scarab 1994 supposably done only 160 hours in Australia. It has been going well however a few weeks ago it started to slow under throttle. As a mechanic / engineer by trade this got my attention quite well.

After a couple of weeks of trial and error I have found when the oil light on the dash comes on the motor instantly cuts out about 50% of the cylinders, after throttling back for 3 to 4 minutes the light goes out and the boat instantly accelerates off. During the testing time I flooded the motor, when it started I had quite a bit of smoke indicating I was getting some oil into the motor. The top motor oil tank is full and the bottom inside 10 litre tank appears to be dropping in oil quantity, how much I'm not sure. I got a sender for the top tank and when I went to fit it found the blue wire disconnected, so I reconnected it and problem still occurred, I replaced the sender and the problem still occurred. What do you think is happening? Should I just throw the oil pump and run on premix? and if I do, where is the sensor that is switching the motor to limp mode? Thanks

flatsfisher57 · Jan 3, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Does the blue wires come out of the cap or is it separate from cap on 3.0 litre they are separate usaully the tank goes bad has a float that sinks after time,take your meter and ohm the blue wires and check it with the manual and see what you get,the circut for the oil alarm comes from the ecu

andy6374 · Jan 3, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Them large Black Max's will die quickly if the oil injection fails. I would opt to remove and go for a 50:1 premix. But as to your problem: There is a warning module (lubalert) which, essentially, connects the overheat switch and low/no oil alarm to the switchboxes. So if the motor overheats or isn't getting enough oil it will cut the RPM's to stay below 2000. Are you getting an alarms? A beep beep beep is low oil and a sustained beeeppppp is overheat. A couple things are possible: -make sure all the connects are good (tight and corrosion free) -the overheat sensor is grounding out -the magnet in the oil tank sometimes drops to the bottom of the tank which results in the engine "thinking" its in a no oil state -or the warning module itself is faulty. It's probably one of the last two suggestions. Run a premix until you get this sorted out. What other maintenance has the engine received since you got it.

Slippery · Jan 3, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Originally posted by flatsfisher57: Does the blue wires come out of the cap or is it separate from cap on 3.0 litre they are separate usaully the tank goes bad has a float that sinks after time,take your meter and ohm the blue wires and check it with the manual and see what you get,the circut for the oil alarm comes from the ecu

flatsfisher57 thanks for the help. The blue wires are connected to a sensor in the top of the tank beside the cap. I will check the float operation, I have no manual for the motor, there are no warning buzzers sounding, thanks

Slippery · Jan 3, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Originally posted by andy6374: Them large Black Max's will die quickly if the oil injection fails. I would opt to remove and go for a 50:1 premix. But as to your problem: There is a warning module (lubalert) which, essentially, connects the overheat switch and low/no oil alarm to the switchboxes. So if the motor overheats or isn't getting enough oil it will cut the RPM's to stay below 2000. Are you getting an alarms? A beep beep beep is low oil and a sustained beeeppppp is overheat. A couple things are possible: -make sure all the connects are good (tight and corrosion free) -the overheat sensor is grounding out -the magnet in the oil tank sometimes drops to the bottom of the tank which results in the engine "thinking" its in a no oil state -or the warning module itself is faulty. It's probably one of the last two suggestions. Run a premix until you get this sorted out. What other maintenance has the engine received since you got it.

andy6374 thanks for the help. I will put the 50 to 1 mix in tomorrow. I will recheck all connections however, all seemed tight the other day. There is no beeping in any way when this problem occurs, light comes on and motor dies to low revs, light goes off and motor goes OK. Where is the heat sensor to check the grounding? Is the magnet attached to the float? What is the magnet for? I will check the float operation, thanks P.S. Someone mentioned to me today they thought there is a sensor in the bottom of the tank and this could be faulty, what do you think? thanks

andy6374 · Jan 4, 2006

Re: 225 oil light comes on, motor goes into limp mode.

First off, since you mentioned you didn't own one, get a Mercury factory manual for your motor. Use it once and it's paid for. All the troubleshooting is in that manual. The overheat switch is usually located on the starboard cylinder head under the #1 spark plug and is usually a tan/blu wire. The temp sensor for the temp gauge is usually located on the port head under the #2 spark plug and is usually tan. The words usually are used because sometimes the temp sensor can be tan/blu while the overheat switch is tan. To check there should be resistance between the temp sensor and the block and an open circuit between the overheat switch and the block. Disconnect the overheat switch at the warning module, and make sure it is an open circuit with the block. If it is a closed circuit, then the overheat switch is grounding out (somewhere). Do you have a little circular warning buzzer under you console inline with the key switch. This should buzz if you have an oil or overheat problem.

andy6374 · Jan 4, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Oh yeah... I'm not exactly sure about the magnet and the sensor at the bottom of the oil tank, since the oil injection on mine is disconnected and I've never had to troubleshoot. Some else will be able to help you here. MY GUESS is that there is a magnet on the float in the tank. When the oil gets low in the tank, the float sinks and the magnet gets closer to the sensor and at some point triggers the sensor. That's way if the magnet fell off the float (and they do) it would trigger a low oil alarm.

gss036 · Jan 4, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Try disconnecting the wires from the float and check for continuity. Should be one bullet connection and a ground. You should "not" have any, if you do then it is probably the float causing the problem.

Slippery · Jan 4, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Originally posted by gss036: Try disconnecting the wires from the float and check for continuity. Should be one bullet connection and a ground. You should "not" have any, if you do then it is probably the float causing the problem.

Thanks for the help Gary, I'll check that to. It was p!ssing down here today so couldn't get out to the boat as it's mored, thanks, Steve

Slippery · Jan 5, 2006

Re: 225 oil light comes on, motor goes into limp mode.

OK, there was a break in the rain today so I had a chance to get out on the water and check out what I have learnt from here. I added 50 to 1 oil mix to the tank. The dash has a temperature gauge with a buzzer in it which goes for a second with the oil and temp light when the ignition is turned on however, the temp. gauge doesn't work as there is no sender unit on the port side under number 2 spark plug where you said it should be, interesting. The overheat switch on the starboard side under number 1 plug has 4 wires connecting to the loom, a black one which goes to earth, 2 brown with a black stripe, one of these is earthed and the other has an open circuit. The last wire is brown with a blue strip, this with is also grounded, interesting. The motor oil tank was down about 3/4 of an inch below the bottom of the neck, so I ran the motor with the top off until the tank was about to overflow and screwed the top on tight. The only wires connected to the motor oil tank belong to the top sensor which I has connected/disconnected and replaced, all made no difference. There appears to be a couple of wires connected to the bottom of the oil pump however, the lack of room here (especially hanging off the back of the duck board) in minimal and I think the bottom cowling would have to be removed to go further, not sure on the procedure of this. Smokes it's arse off now, especially at idle so I guess it was getting oil and the problem is a sensor. Road tested and light came on and went into limp mode within 400 yards, within 60 seconds light went off and away it went, ond so on, so it wasn't the top tank being a bit low, guess I have to get the bottom cowling down and operate on the oil pump/wiring/sensor? any more thoughts? Sorry about the Sermon Thanks ---------- Steve

andy6374 · Jan 6, 2006

Re: 225 oil light comes on, motor goes into limp mode.

POSTED BY SLIPPERY: "The overheat switch on the starboard side under number 1 plug has 4 wires connecting to the loom, a black one which goes to earth, 2 brown with a black stripe, one of these is earthed and the other has an open circuit. The last wire is brown with a blue strip, this with is also grounded, interesting." Get a multimeter. Take one of the brn/blk and if one of them measures a resistance between it and the block (earth) then that one is for your temp gauge. If you ground this wire, the temp gauge should jump to "H" (hot). Try ungrounding the brn/blu wire and see if it is an open or closed circuit with the block. Should be an open circuit. This one should get routed to your warning horn (or possibly to the warning module, doesn't matter if you do the warning module it will go into limp mode if it overheats). If you ground this wire the warning horn should go off. You'll want to get these functional, at the very least the overheat switch with the alarm. What's your serial #? Sounds like you are getting oil. Just gotta play with the sensor. If it were me, I disengage the oil injection and go fish!

gss036 · Jan 6, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Is this an EFI or carbed engine?

andy6374 · Jan 6, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Not that I should be the one answering, but with the brn/blk wires for the temp sensor i would guess efi. But then my carbed engine has heads off an efi and thus I have brn/blk wires too

gss036 · Jan 6, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Andy, the reason I ask is that the EFI's have a throttle position sensor in the mix to consider in trouble shooting. Also has an electric fuel pump. The Tan/Blk wire should also be connected to the Throttle Position sensor and then T's w/temp sensor and then runs to the EFI box. There is aslo an Air Temp Sensor involved and it has 2 brn wires coming off it and one on the right side plugs into a black connect, then to the EFI sensor. There is an orange wire which comes off the Throttle sensor,T's into the Tan/Blk on the head temp sensor then goes to the EFI box(sensor), there is a total of 16 wires on the EFI box. They aslo interact w/both switchboxes. This is all above my expertise as I have never worked on an EFI. Just info from the manual.

Slippery · Jan 6, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Thanks for all the help, Yes I will have to get a manual, not easily available over here, may pay for me to purchase from this web site and get airmailed over. When I wrote the following; "The overheat switch on the starboard side under number 1 plug has 4 wires connecting to the loom, a black one which goes to earth, 2 brown with a black stripe, one of these is earthed and the other has an open circuit. The last wire is brown with a blue strip, this wire is also grounded, interesting." This test was performed with an ohms meter, the above circuits were either open or closed, there was none with resistance, when I said, The last wire is brown with a blue strip, this wire is also grounded, I should have said it was a perfect earth. The papers say it's a 1999 model Serial Number OGOB1518 looks to have a vacuum petrol pump and has carbs, definitely not EFI, but oil injection. Yes, I would certainly like to have the "overheat switch" working, would like to have the temperature gauge working as well. Under the dash the temp. gauge appears to be connected by brown wires to the loom, does this mean if I put a temp. sensor in the port head, there could be wiring close to hook up and it may go? I'm quite happy to disconnect the oil injection system, I see many procedures for this on the forum, which would be best for me, do I need to remove the bottom cowling, do I need a specially shaped plate to cover the hole, do I remove all oil lines from the pump and just block them? On another note, when I approached my boat, the motor appeared to be in the water by about 4 inches instead of out by 6 inches, all was working well last time I used the trim. Now trim hydraulic pump revs louder and higher with very little or no movement (don't yah just love it!) if you flick from up to down it moves better but not correctly, just like hydraulics that are low in oil. If so, where has the oil likely to have gone so quickly and where do I refill it and with what viscosity, I expect an SAE 5 or 10? I guess with motor up? Thanks in advance. ------------------- Steve

andy6374 · Jan 8, 2006

Re: 225 oil light comes on, motor goes into limp mode.

On the strb. side of the engine there is an engine wiring harness. It's a big black plug. It's made up from two harnesses, and external and internal harness. The external runs from the ignition/key switch (where you have the tan (you said brown) wire under the dash running to temp gauge.) to the engine then it connects to the internal harness which runs to all the necessary components, i.e. choke, starter... But where the external harness plugs into the internal harness there should be some bullet connects coming off of it. A green and blue for tilt and trim, a brn/wht for trim sender, and a tan wire for the temp gauge. So get the temp. sensor and plug it into that bullet connector. The overheat switch is important to have operational as well. But if monitoring your engine temp, a water pressure gauge is the best way to go. By the time the alarm goes off or when you notice them gauge is pegged towards "H", you've already done damage.

Slippery · Feb 1, 2006

Re: 225 oil light comes on, motor goes into limp mode.

Originally posted by andy6374: On the strb. side of the engine there is an engine wiring harness. It's a big black plug. It's made up from two harnesses, and external and internal harness. The external runs from the ignition/key switch (where you have the tan (you said brown) wire under the dash running to temp gauge.) to the engine then it connects to the internal harness which runs to all the necessary components, i.e. choke, starter... But where the external harness plugs into the internal harness there should be some bullet connects coming off of it. A green and blue for tilt and trim, a brn/wht for trim sender, and a tan wire for the temp gauge. So get the temp. sensor and plug it into that bullet connector. The overheat switch is important to have operational as well. But if monitoring your engine temp, a water pressure gauge is the best way to go. By the time the alarm goes off or when you notice them gauge is pegged towards "H", you've already done damage.

Andy You are on the money, the brown wire was not connected where you said by the large plug at the bottom. I connected it and we now have a temperature gauge. Ran the motor up for 30 minutes and all was normal, dropped her off the mooring and went for a cruse, 1/2 throttle and all was well, 3/4 throttle and the temp started to build, 7/8 throttle and temp shot up to the red, as the needle hit the red

THE OIL LIGHT CAME ON AND THE MOTOR WENT INTO LIMP MODE

Some imbecile has swapped the oil and temp light in their holders.

I'm very lucky I didn't seize it. Wasn't an oil problem at all

So it's off the slip ASAP for a service and new impeller. I'd like to thank you very much for your help, your info has led me to the problem.

This is what forums are all about. Thanks Steve

andy6374 · Feb 2, 2006

Re: 225 oil light comes on, motor goes into limp mode.

While its getting service its probably worth your while to get the tstat and poppet assembly serviced as well. Then every component of the cooling system will be in tip-top shape. P.S. Don't just replace the impeller, get a kit and install all new gaskets.

225 oil light comes on, motor goes into limp mode.

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