'94 200 HP Merc Oil Alarm

rfav21 · May 22, 2010

While running engine today for first time this season the alarm came on for what I think is an oil pump issue. The alarm was a pulsing horn, so I checked the oil levels in the remote tank mounted under a cover in the stern of the boat and that was full. I also checked the reservoir tank mounted under the engine cowl and that was full also. My questions are: 1) Will the remote tank float switch give me an alarm? 2) The reservoir cap/float, the wires appear to be twisted and I suspect this may be my issue but want to see what else I can look for. Any suggestions? Thanks in advance.

CharlieB · May 22, 2010

Re: '94 200 HP Merc Oil Alarm

There is no sensor in the remote tank.

The sensor in the cap of the engine mounted tank is very sensitive, loosen the cap while running, wait until oil just begins to leak out from under the cap then retighten. The wires get twisted cause someone plugged them in before installing and tightening the cap.

The alarm module compares the rotation signal from the oil pump to the ignition pulse on the green wire to coil of cyl #4, any difference in the two signals then the alarm sounds.

Check spark on ALL cyl's, misfiring on #4 will cause an oil alarm.

rfav21 · May 22, 2010

Re: '94 200 HP Merc Oil Alarm

Thanks for responding CharlieB.

<There is no sensor in the remote tank.>

The remote tank on my boat has a float switch, maybe this is for the oil gauge on the dash? I'm not 100 0/0 sure since I just purchased the boat.

<The sensor in the cap of the engine mounted tank is very sensitive, loosen the cap while running, wait until oil just begins to leak out from under the cap then retighten. The wires get twisted cause someone plugged them in before installing and tightening the cap.>

I'll do as you suggest as far as filling the engine mounted tank. As far as the wires being twisted, this is how they were when I got the boat, but I'm inclined to changed the cap just to eliminate the possibility of this being part of the cause.
Also, when I loosen the cap with engine running like you suggest is it safe to assume the pump is good if the oil level rises?

<The alarm module compares the rotation signal from the oil pump to the ignition pulse on the green wire to coil of cyl #4, any difference in the two signals then the alarm sounds.

Check spark on ALL cyl's, misfiring on #4 will cause an oil alarm.>

The engine seemed to be running smoothe. But I'll see what I can do to check for a misfire on #4 as well as check the connections at the coil. Thanks for you help with this.

j_martin · May 22, 2010

Re: '94 200 HP Merc Oil Alarm

If you have lots of money, send me some. Otherwise it's a very good idea to diagnose the problem before you buy parts.

Twisted wires won't hurt anything. The electricity doesn't get dizzy. If you suspect the cap, disconnect the 2 wires. If the alarm goes away, then the cap is defective.

The rest of the diagnostics takes a meter.

hope it helps
John

rfav21 · May 23, 2010

Re: '94 200 HP Merc Oil Alarm

Thanks for the reply J_Martin. Believe me I'm not looking for reasons to throw money away, but where the wires go into the cap the black is already bare from the previous owner, I'm just thinking maybe the wires are damaged inside the cap as well. I will do like you suggest though and try disconnecting the wires to see if the alarm continues. I'll also put an ohmmeter across the two wires and see if there is any short between the two.
What else do you suggest as far as electrical tests? Again thanks for your help.

rfav21 · May 23, 2010

Re: '94 200 HP Merc Oil Alarm

Ok, I understand the idea behind checking the cap and wires. But besides the cap and wiring how do I check the rotation sensor in the pump? I notice 3 wires coming from sensor, blk-gnd, white, lt blue/wht. What readings should I get with engine running, I assume one of the two is 12V+, does the other send a variable voltage or 12V while sensing rotation? Any help is appreciated.

j_martin · May 23, 2010

Re: '94 200 HP Merc Oil Alarm

It's a hall effect proximity sensor. You have to test it with it connected, so it's getting 12 V and ground. I think the output goes from near ground to 5 V. I'm not sure. You turn the motor over slowly by hand and watch the meter go up and down.

The whole test procedure is in the Mercury OEM Maintenance manual.

If the wires are damaged to the point that wires are exposed, then it should be replaced.

hope it helps
john

rfav21 · May 24, 2010

Re: '94 200 HP Merc Oil Alarm

Hi John,
Thanks for the help with this issue. I have a Seloc manual but didn't find the rotational sensor, but I'll try as you suggest on Wed when I'm at the marina. Also I'll check the cap a little more closely when I do these other checks. Again, thanks for all the advice. I'll post results Wed or Thurs.

nosgsxr · May 24, 2010

Re: '94 200 HP Merc Oil Alarm

What ever u do. Please put some oil in your gas tank before u run the motor anymore. Cause if there is no oil getting to the piston than u will have a huge problem. I know from this just happing to me. I bought parts and it wasnt the problem. Now in going to get a new used motor in the morn. 4000.00 later. Please add oil it wont hurt anything to be sure. These people on here are telling u right they are the same people who helped me find my problem but it was too late.

rfav21 · May 24, 2010

Re: '94 200 HP Merc Oil Alarm

Thanks for the heads up nosgsxr. I've got a mechanic looking at it tomorrow just to be sure it's getting oil. I've also got a full tank of gas, 90 gal or so. I guess if the pump is not working I'll be dumping a couple gallons of oil into my tank and disable the oil pump and all the warning devices. If all is ok I would like to leave everything intact. Again thanks for the heads up.

nosgsxr · May 25, 2010

Re: '94 200 HP Merc Oil Alarm

no problem just trying to help out and save you some cash....i will be parting out my motor so if you need anything let me know trying to recope some of my loss..

rfav21 · May 26, 2010

Re: '94 200 HP Merc Oil Alarm

I took a look at my engine today, couldn't wait for the mechanic. The float in the engine mounted reservoir checked out ok even with the wires twisted. Pulled the pump and sure enough the plastic gear that drives the pump is gone. So,I'll be doing away with the oil injection system. The blue wire from the float is now disconnected, pretty sure thats ok. So, my questions are:
1) How do I disable the rotational sensor to prevent an alarm? Is it as simple as disconnecting the blue/w and white wires, or does the warning module look for some kind of signal?
2) Is it ok to leave the old pump in place?
3) Do I need to remove the wire going to cyl 2 or 4?
4) What about the old drive shaft, is it ok to leave it in place or should it be removed?
Thanks to all for the help with this.

j_martin · May 26, 2010

Re: '94 200 HP Merc Oil Alarm

rfav21 said:
I took a look at my engine today, couldn't wait for the mechanic. The float in the engine mounted reservoir checked out ok even with the wires twisted. Pulled the pump and sure enough the plastic gear that drives the pump is gone. So,I'll be doing away with the oil injection system. The blue wire from the float is now disconnected, pretty sure thats ok. So, my questions are:
1) How do I disable the rotational sensor to prevent an alarm? Is it as simple as disconnecting the blue/w and white wires, or does the warning module look for some kind of signal?
2) Is it ok to leave the old pump in place?
3) Do I need to remove the wire going to cyl 2 or 4?
4) What about the old drive shaft, is it ok to leave it in place or should it be removed?
Thanks to all for the help with this.

Hope you haven't hurt the engine messing around. Oil it up and check compression. If it's good and you have no knocks, you dodged a bullet. Then here's the oil system removal instructions.

Re: oil injection removal Merc V6 only

You need part number 43453 if it is available. That retains the pump driveshaft bushing and plugs the hole where the pump mounts. Then remove the oil components and the warning module. You'll also need to remove the fitting that the oil tank pressure hose attaches to and plug the hole in the block.

Order three stickers (37-818029 1), one to mount near the fuel fitting on the motor, one for the dash, and one near the fuel fill fitting on the boat. They'll alert the operator that the gas needs to have oil added. One frequent problem we see here regards the infamous "brother-in-law" that forgets to add oil to the gas and roaches the motor.

You should probably replace the fuel lines where the fitting for the oil T's into the fuel line

hope it helps
John

CharlieB · May 27, 2010

Re: '94 200 HP Merc Oil Alarm

Yes, remove the pump drive shaft.

Yes, remove the green wire, otherwise the alarm will still sense the no oil pump rotation compared to the ignition pulse, and alarm.

LEAVE the alarm module, you still need the temp protection.

rfav21 · May 27, 2010

Re: '94 200 HP Merc Oil Alarm

John, thanks for the help with this. When I was operating the boat last week as soon as the alarm for low oil would sound I would shut the engine off and wait 15 minutes or so, I was then able to limp back to the dock. Also the high temp alarm never sounded, so I'm hoping I dodged that bullet. I'll do a compression test to be sure.

Charlie B, thanks to you also. I definitely want to keep the temp sensor in place to avoid any additional trouble. Again, thanks to all. I will post results from compression test and report any other troubles should there be any.

j_martin · May 27, 2010

Re: '94 200 HP Merc Oil Alarm

If it's like my 88 v6, the oil alert has absolutely nothing to do with the overheat sensor. They both drive the same alarm circuit to ground, but they operate independently.

rfav21 · May 28, 2010

Re: '94 200 HP Merc Oil Alarm

I was just thinking that if the engine wasn't getting oil then maybe that would cause an overheat condition. Today went down to the Marina and disabled the wiring and oil injection lines. Also did a compression test with the engine cold all cylinders read between 118-120, so it seems compression is good. Thanks to all for the help. I'll post any other problems or questions should anything come up.

j_martin · May 29, 2010

Re: '94 200 HP Merc Oil Alarm

rfav21 said:
I was just thinking that if the engine wasn't getting oil then maybe that would cause an overheat condition. Today went down to the Marina and disabled the wiring and oil injection lines. Also did a compression test with the engine cold all cylinders read between 118-120, so it seems compression is good. Thanks to all for the help. I'll post any other problems or questions should anything come up.

Naw, the primary symptom is it just plain quits.

Sounds like you dodged a bullet. Good luck from here on.

John

rfav21 · May 30, 2010

Re: '94 200 HP Merc Oil Alarm

Hi John,
Took her out for a pretty good run today and all seems good. Gotta get used to mixing gas and oil again but if thats all I've got to worry about we should be fine. Thanks again.

'94 200 HP Merc Oil Alarm

Seaman Apprentice

Vice Admiral

Seaman Apprentice

Admiral

Seaman Apprentice

Seaman Apprentice

Admiral

Seaman Apprentice

Petty Officer 3rd Class

Seaman Apprentice

Petty Officer 3rd Class

Seaman Apprentice

Admiral

Vice Admiral

Seaman Apprentice

Admiral

Seaman Apprentice

Admiral

Seaman Apprentice