Mariner 15hp 2 stroke problem ongoing

[sunquest]

Following my post on the above subject in August, I have now narrowed it down to an electrical problem. Only one cylinder is firing and I have eliminated the high voltage (spark) coils by changing over the wiring and HT lead. This leaves a black box which is resin sealed of which I have no idea what it does or a wiring problem Any ideas ? Thanks in advance - Geoff

 

[VicS]

This thread refers presumably http://www.ybw.com/forums/showthread.php?t=326929

You have not told us the serial number so a bit difficult to look up the specific model with certainty. I'm guessing OT98----

I imagine the electrical system is something like http://www.boats.net/parts/search/M...HRU 0T999999/Electrical Components/parts.html and that the sealed item is the "switch box" part # 8.

If so that is the electronic module which is the heart of the ignition system.

Difficult for the DIYer to carry out any tests or checks on it other than replacement ......its rather expensive though.

Having established that you only have a spark on one cylinder and eliminated the HT coils and leads that pretty much only leaves this module.

 

[sunquest]

Thanks Vic. Your help is always very much appreciated. I originally suspected the float level being too high as the engine on full thottle ran well. As the engine is at home and able to run and dismantle without losing nuts etc to the deep, the diagnosis was conducted in a less vulnarable and therefore less stressful environment. My next call will be to Highway Marine at Sandwich to ascertain price and availability of the switch box. Geoff

 

[GrahamD]

I had a 15hp Mariner which had an very frustrating intermittent electrical fault . Turned out that the wire to the stop button at the end of the tiller had chafed within the tiller and when this was disconnected the engine ran beautifully. Apparently this can be a common and not obvious fault so eliminate this before you go buying any other bits.

It was still in perfect working order when three weeks later some local gentlemen nicked it from the boat in the middle of the night. Wish I hadn't bothered to fix it