1987 Mercury 80 hp Continuous alarm question

[Drano103]

I was out on the lake for tubing for about half an hour. I had 4 in the boat while pulling 2. The last ten minutes of that i was pulling the tube and would try to give it full throttle and it would cut out. So after those ten minutes the continuous alarm went off and I cut off the engine. I let it sit for 10-15 min. Trying the key in just the on position and it would go off right away before starting it. So i started it and gave it thottle with no propellar propultion for bout 10 seconds. I checked the oil resevior and it was full, then I checked the spark plugs and they had oil on them. I know now that it's the overheating alarm from reading and talking to mechanics. I ran the boat at idle speed for about 10 min to the dock. I tried giving it full thottle on the way to the dock and all it would give me is half power if that. So I let the boat sit for two days and tried the puting the key in the on position while in the garage. Hoping that it had cooled down and that maybe it was the water impellar that needed to be replaced, because of the overheating. Even though it had water coming out of the pee hole in with the problems. I still haven't done anything besides that. I would appreciate any ideas or help with figuring out what is wrong with my engine and continuous alarm that is going off? Thank you to anyone that can help!

 

[emckelvy]

Re: 1987 Mercury 80 hp Continuous alarm question

I'd bet it's the alarm module. But, before buying expensive non-returnable electronic parts, you might want to do a bit of troubleshooting first.

Find the temperature sensor, on the cylinder block water jacket cover (the one over the spark plug holes). The sensor should have one wire coming out of it. Unplug the wire and see if the alarm goes away.

Do the same thing with the oil tank level sensor, unplug the wire going to the level switch in the tank.

If the alarm is still there, the module's likely shot. If the alarm goes away there's a problem with the sensor or float switch.

In the case of the temp sensor, you can merely replace that part.

In the case of the oil tank, the reed switch in the bottom is replaceable, but usually what happens is the metal washer glued to the oil tank float has come off the float and gone to the bottom of the tank, causing a constant alarm.

Unfortunately the only way to fix that is to replace the entire tank.

HTH & let us know what you find...........ed

 

[Drano103]

Re: 1987 Mercury 80 hp Continuous alarm question

I found what the problem was thanks to you. I unplugged the oil tank sensor and the alarm went off. I was afraid much more had gone wrong. Thanks again for your help to resolve this matter.

Jeremy