Mercury 80hp 3 cyl runs and then randomly cuts out and no spark after, 3 times now?

Hi,

I have a Mercury 80hp 3 cylinder, serial 9483100, i think it's early 90's.

Boats been running great all year, I was boating the other day, fine for 20 minutes or more then the engine instantly cut off, not a fuel splutter, like someone pulled a kill switch, and then no engine spark.
never happened before. I checked all the fuses, the leads, wiggled any wires to check everything was fine, it then re-started, great i thought, 5 minutes later same again, medium throttle cruising, sudden engine kill. again, no spark.

i check all the connections i could think of the next week, it started in the shed, i idled it for 3 minutes to check it was all good and it was running fine, then sudden shut down, no warning.

the same again today, it's like it has a deamon in there!

something cuts it off and no spark.

a friend is an auto electrician, he had a poke and couldn't really help, he said when i was cranking it i was getting a good negative pulse and on the previous time it ran he checked i was getting good positive and negative pulse to the coil. I don't think he really new what he was doing? not like a car, but i was great full for the help.

Any clues on what might be the cause?

where do i start looking?

i tried disconnecting the mercury tilt switch, still no dice.

Re: Mercury 80hp 3 cyl runs and then randomly cuts out and no spark after, 3 times no

not sure if that model has one but you might try and find out if it has a kill switch... if it does disconnect it and try starting again... not sure if this is any help but it might be a start

Re: Mercury 80hp 3 cyl runs and then randomly cuts out and no spark after, 3 times no

Sounds like a part is getting hot and stops working. about all you can do is get a manual and run tests when it dies. I had a friend with the same problem and after several weeks of trouble shooting he asked me to run some electrical components tests and the stator had low ohm values and we replaced it and it was fine.

Re: Mercury 80hp 3 cyl runs and then randomly cuts out and no spark after, 3 times no

There is no kill switch on this one, not sure what order to go about testing it all.

Re: Mercury 80hp 3 cyl runs and then randomly cuts out and no spark after, 3 times no

I bought an online manual for the boat and it turned up as a 391 page PDF!
I find it much harder to understand than a proper book paper manual I had for my last motor.
There's a few nights reading there alone.

If there's any pointers on the order at which I should hit each component that would be really appreciated, then I can probably find it quicker, heaven knows I may even get out boating while the suns still shining here!

Thanks all for input so far.

Re: Mercury 80hp 3 cyl runs and then randomly cuts out and no spark after, 3 times no

Check the easy stuff first. Spark plugs, plug wires, wiring harness, connection points, carbs, fuel lines, fuel pumps... Sounds kind of like the fuel is vapor locking on ya or pumps are not working.. Idk much about your motor but these are some things to consider on all motors.... Also when was the last tune up?