View Full Version : 1987 Mercury 150 V6 just stopped when running at 3800 RPMbs

Anthony Panek
05-05-2003, 01:53 PM
I was getting ready to pull the boat last season and was taking a last spin when one of the 2 150's running at 3800 rpm's just quit no studder no nothing just dead. I have OHM tested the Stator and Trigger and they seem to be both within the limit. I also swapped Switch boxes with the other running motor and still no spark. Switch boxes from dead motor ran just fine in the other one. Anyone have any idea to check something else before I call the traveling mechanic who is extreamly expensive.

Thanks TonyIII

05-05-2003, 02:21 PM
" Anthony,

If you are getting no spark on any of the cylinders, you are left with something that is central to all coils - it's not going to be a switch box as there are more than one. The options are stator, trigger, and wiring. My first guess would definitly be wiring.

To kill the engine, there is a circuit that puts ground to a post on the switch boxes. By pulling the kill switch, turning the key off, or safety mechanisms, ground is placed on this circuit & it kills the spark. It's a black wire, check for ground there (or on each switch box post that it sits on). Your engine probably has a thing called a mercury switch - it's a little gizmo that grounds to the block & will route ground to that black wire & kill the engine if it's inverted - these things can go bad; a possible cause if you find ground where it shouldn't be.

Jon "

05-06-2003, 08:41 AM
" Jon, What exacty is the mercury switch job?? To keep motor from being started when not trimmed down ??????/ Thanks "

05-06-2003, 04:53 PM
" Gary,

I *think* it's there so when you capsize nobody get's wacked with the prop. Mine starts fine fully tilted up and the switch is new.. probably some USCG saftey requirement.. I left mine in, but a friend of mine who holds a capt. license, and is a mechanic, told me he takes them out.. one less thing to break and put you in the rocks I guess.. One upside is though, if the switch kills the boat when you invert the engine, the chances of totally destroying your outboard are lessened... not what would cross my mind floating around in 40 degree water though ;),

Jon "