1992 Mercury 60HP 2stroke Constant Alarm

[capperja]

Good Evening All,

New to forum but have been reading through several posts and have already learned a lot. I bought a used 1992 Mercury 3 cyl 60hp 2 stroke Outboard with a Jet on it last summer. Completed my bass tracker restoration and mounted the outboard, took it for a spin the other day and am getting a continuous alarm as soon as I turn the key to the halfway position.The alarm remains on even if the outboard is not running and regardless of temp.

I read through some posts with regard to the magnet on the float in the oil tank. I unplugged the two blue bullet connectors one at a time and neither stopped the alarm so I'm ruling out the oil tank for now.

Today, I unplugged a butt connector that had one tan wire coming into it and two tan with blue stripe wires coming out of this and that made the alarm stop. The tan wire comes from a little black box next to the oil/fuel pump. I traced one tan and blue striped wire going back to the female end of the plug that goes to the remote box and one that appears to go underneath of the outboard and to the cylinder head. Would this feed a temp sensor or thermostat?

Additionally, I've got an extra set of wires that plug into the remote box. I'm not running a trim gauge, tachometer, speedometer, etc. so I'm assuming I can go about not using it.

Any and all help is appreciated, thank you.
I've attached some pictures for reference.

 

[markhodges78]

welcome to the club
could you post up a serial number for reference,
Also It could be your oil float alarm or your oil pump sense alarm if you are mixing the oil and fuel you can bypass this alarm if you are not mixing then you have problems that need to be addressed

 

[capperja]

Thank you and thank you for the reply. 0D187247, I unplugged both of the bullet connectors for the oil reservoir thinking it might be the magnet on the float. Alarm continued to sound. Also, from what I've read, the alarm is a continuous tone which would indicate an overheat condition, whereas an oil alarm is a series of beeps.

 

[flyingscott]

Overheat alarm

 

[markhodges78]

With a cold engine unhook your over heat switch that is in the head and check for continuity to ground.. if you have continuity then the switch is bad. Should be Tan/ blue wire

 

[flyingscott]

With a cold engine unhook your over heat switch that is in the head and check for continuity to ground.. if you have continuity then the switch is bad. Should be Tan/ blue wire

He already disconnected the tan wire and the alarm stopped.

 

[markhodges78]

Today, I unplugged a butt connector that had one tan wire coming into it and two tan with blue stripe wires coming out of this and that made the alarm stop. The tan wire comes from a little black box next to the oil/fuel pump. I traced one tan and blue striped wire going back to the female end of the plug that goes to the remote box and one that appears to go underneath of the outboard and to the cylinder head. Would this feed a temp sensor or thermostat?

The over heat switch should be Tan and blue not Tan so pay attention to that. You should have a Tan wire that goes to the head that goes to the temp sensor and a Tan and blue for the over heat alarm which goes to the alarm module I have attached a wiring diagram for reference

 

[QBhoy]

Has this been converted to a jet ? Sorry if you said so or otherwise previously. Was just thinking and wondering about the earthing circuit if it has ? And where it earths to on the engine externally. As in the bonding wire that’s usually ran down to the lower unit and maybe trim pump off it too.
Also that harness loose there. Is that not the control harness ? That should run up to the remotes then dash ?

 

[markhodges78]

Has this been converted to a jet ? Sorry if you said so or otherwise previously. Was just thinking and wondering about the earthing circuit if it has ? And where it earths to on the engine externally. As in the bonding wire that’s usually ran down to the lower unit and maybe trim pump off it too.
Also that harness loose there. Is that not the control harness ? That should run up to the remotes then dash ?

I'm not sure if it's been converted but the wiring should be the same and it's the best I had also if tan wire from module has continuity to ground then that is your problem start there if you no longer use the tank take it out

 

[QBhoy]

I'm not sure if it's been converted but the wiring should be the same and it's the best I had

Ok. And there’s nothing lying loose and shorting into the bilge or that ? These wee control and sensor wires are meant to be either connected up or capped when not in use, I’d think.
is there an earth strap that goes down the mid section somewhere? Like normal engines have ?

 

[capperja]

Wow, I appreciate all of the replies and ideas. I hadn't been able to log on until this evening so I'll do my best to answer what questions have been asked. I bought the outboard used, it already had the jet pump mounted to it, came with the propped lower as well. I had not planned on using the loose harness that is pictured because I'm not running any gauges on the console. I'm not sure in regards to the earthing circuit, I can tell you the trim switch works on the outboard and now the trim switch on the shift lever works as I replaced that today.

Prior to reading these replies, I contacted Mercury for the proper part numbers with regard to a thermostat kit (14586A6) as well as a new heat sensor (787992). I need to test for continuity, as you all had stated, with regard to the heat sensor, the thermostat and poppit assembly appeared to need replacing and the gasket was very old for the thermostat housing.

Again, I appreciate all of the help and will be sure to post back with my findings.

 

[capperja]

Thank you for the help thus far. I replaced the thermostat, poppit, and diaphragm today with the previously mentioned kit. Tested the old thermostat, out of curiosity, and it was functioning correctly. I am still waiting on the new heat sensor. Should be here in the next couple of days.

I removed the heat sensor from the block today while leaving it plugged in, now the control box beeps once when the key is turned to the run position. Unless I'm mistaken, I believe a single beep confirms a good system check. Thinking all was well I pushed the heat sensor back into the block and went over to the boat ramp. Outboard fired right away, let it idle with the throttle increased for around 2-5 minutes and the alarm came back on. No leaks from the thermostat housing, cylinder was not hot and the water coming out of the telltale was cool. If I manipulated the throttle lever a little sometimes the alarm would cut in an out or change tone slightly. I shut the outboard down, waited about a minute and repeated this procedure three times.

As of now, I'm going to see what the new sensor does for me once it arrives, if that doesn't fix it I guess I'm going to have to check for continuity in every wire starting from the outboard and working my way up. I appreciate the help. ordered a service manual today to help. Also, if anyone could tell me what this component is, I'd greatly appreciate it. Referring to the rubber hose coming from the top of the jet pump that has a plastic stepped point on the other end. My guess was that it's a speedometer. Pics attached.

 

[capperja]

Wanted to provide an update and thank you all for the help thus far. I think I’ve got this figured out, markhodges your diagram was extremely helpful.

I did some diagnostic testing yesterday and confirmed/found these items all while the outboard was cold.
The tan wire that comes off of the warning module and goes into a 2-1 female bullet connector (tan with blue stripe) coming out of it is hooked up properly. If I disconnect the heat sensor, I still get my constant alarm. If I disconnect the tan wire from the module, nothing happens, which makes sense because that circuit is no longer complete. This all leads me to believe that I have a faulty warning module.

Additionally, I believe I do not need to accessory harness to the control box as I do not have a temp gauge, trim gauge, separate ignition, or tachometer. I tested continuity and confirmed that everything is accounted for.

I will post back to confirm that this fix works once the module comes in (assuming it’s not faulty as well).

In summary, I had a constant tone when the key is turned to the run position.

Continuity Testing:
-Disconnected Oil sensor wires, no change
-Disconnected Heat temp Sensor, no change
-Disconnected the tan wire coming from the warning module, no audible tone from control box

Components Replaced:
-Poppit Valve Assembly and Thermostat
-Heat Sensor
-Water Pump

In addition to markhodges diagram, see attached pic for Mercury wire coding sent to me by a friend. Also, if anyone can tell me what that tube with the stepped post on it (pictures in previous post) is for I’d greatly appreciate it. My assumption was that it’s for a speedometer. Thank you again all, you’ll hear from me soon.

 

[markhodges78]

My assumption was that it’s for a speedometer. Thank you again all, you’ll hear from me soon.

Your assumption would be correct it is the for speed odometer and the warning module is for the oiler as well if it's still being used then replace it ( if you premix the gas ) then toss the module