Help Please. Constant alarm on Mercury 200 EFI.

RangermanRangerman Titusville FLPosts: 78 Greenhorn

I swapped engines on 2 bass boats and put a 1996 200 EFI on my bass boat.  My original engine had the oil injection for oil, but the 200 EFI already had the block off kit applied for premix fuel.  I ran the 200 EFI on the boat it came on before I swapped engines for about a year with no problems and no alarms.  I premixed the oil on the boat I swapped the engine to 40:1 since it’s the first running and with the fuel line disconnected pumped the primer bulb until I got one quart of gas out then dumped that gas in the tank so I have premix fuel up to the engine and then connected the fuel line.  The first time I turned the ignition on I got the constant alarm.  I started the engine and ran it briefly and it ran great.  Could it be that the engine thinks it's not getting the injection oil it expects?  Can anyone tell me what this alarm means and how I can stop it?


I tried a couple of things.  I disconnected the tan wire coming from the cable attachment and the alarm still sounds.  I disconnected the tan wire with the blue stripe coming from the lower of the 2 boxes on top of the engine (low oil warning module?) and that makes the alarm stop.


  • GreymareGreymare North AlabamaPosts: 17 Greenhorn

    I know very little about the setup on the Mercury engine so everything I am about to say is strictly based off the way I am assuming it was engineered. With that said I would think that the alarm is for either a low oil level sensor or a low oil pressure sensor. Even though your engine isn’t needing it the ecm doesn’t know it has been removed/by passed. The odds are that you need to connect the wires together rather than disconnect them. Again I am assuming they would make it where if everything is working properly it would create a closed circuit rather than an open circuit. This way if a wire got broken your alarm would automatically go off so you would know there was a problem. If it was set for an open circuit for normal operations then you could have the sensor unplugged and never know when it failed. Maybe this will help. If not maybe someone else will jump in here soon.   

  • james 14james 14 Posts: 3,015 Moderator
    So the engine was run with premix on one boat and the alarm started after you moved it to another boat? Or did you run it with the oil pump on one boat and then try to premix it on the other?
  • retiredviejoretiredviejo San PedroPosts: 274 Deckhand
    The 200 EFI from that year (range) has around 6,592 sensors that were designed specifically to serially annoy each and every customer. Repeatedly, and constantly. Like a Johnson, most Merc's will blow up long before they are paid for. Half the sensors report phantom problems, the other half never worked properly to begin with. It is, and remains, the only outboard in history to achieve the single worst rating/review in Consumer Reports history. Ahead of the Yugo. 
  • Gary SGary S Posts: 1,676 Captain
    I belive a solid alarm is temp overheat. Oil is a not constant.
  • RangermanRangerman Titusville FLPosts: 78 Greenhorn
    In answer to James 14, the engine was run with premix on the boat I bought with the 1996 200 EFI on it and ran well on that boat.  The previous owner applied a small cover over the hole where the oil pump used to be.  But the alarm may have been non-functional on that boat because there was no alarm verification tone when you first turned the ignition key to on.  On the boat the 200 EFI was transferred to before the engine transfer (then it had a 1991 Merc XR4 150), when I turned the ignition key on there was a brief tone verifying the alarm works.  So its possible that when the 200 EFI was on the boat I bought it on that the engine was sending the alarm warning but the boat lacked the capability to produce it.
  • james 14james 14 Posts: 3,015 Moderator
    Based upon my experience with the same exact issue (alarm buzzer wasn't working and I didn't realize it) you're best bet is to get the motor to a shop that will run the codes for the you. They may not charge you anything or they may charge you a half hour of labor but it'll be worth it so you know exactly what the issue is.

    If you look here:

    You'll see a list of codes and what they mean. I can't say for sure they are the same for your exact Mercury but they probably are. It's likely that it has something to do with the oil pump and it's reading that the level is low and/or the oil pump has failed. However, as you can see by looking at the list, it could be something else as well. Odd that it hasn't put your engine into safe mode BUT your model may not have that function.

    Like I said, have the codes run.
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