1983 omc saildrive

" Hi all,

I have a 1983 OMC

" Hi all,

I have a 1983 OMC saildrive that is basically a 35 hp head detuned to provide more thrust. My problem is that it seems to be firing only on one of the two plugs. The top plug is very black and fouled but the bottom plug is clean and fine. Wondering if I am getting water in the top one and that is preventing it from firing. The engine runs, rough, and powers the boat at about 3/4 normal speed for a given rpm. Sometimes it runs fine. If i replace the bad plug it runs fine for 10-15 mins and then starts to run rough again. Any ideas or anyone in the chicago area lokking for work? thanks "

i would say it is the capacit

i would say it is the capacitor discharge?

"Glenn.... Things you should d

"Glenn.... Things you should do first is to check the compression and ignition (spark). The compression should be in the 100lb area and close to even on both cyls ie 120/118 or there abouts, not 120/90 or so. The spark should jump a 7/16" gap with the spark plugs out.

The fact that when you install a new s/plug, the engine runs fine for a short time, indicates an ignition problem such as weak fire. The "black" s/plug scenerio also indicates weak ignition.

Try this... After checking for loose ground wires or other wiring irregularities, switch the coils (top to bottom) being sure to also switch the orange wires in the plug leading to the p/pack so that they fire properly. If the problem follows the coil and the problem cylinder is now the bottom cylinder.... obviously you have a bad coil. If the problem cyl remains the top cylinder after switching the coils, I would suspect the p/pack, assuming that nothing is amiss with the wiring. Let us know what you find.

Joe "

" Joe,

Sorry but I have bee

" Joe,

Sorry but I have been busy and unable to work on the boat. However I did replace the powerpack and suspect coil from onboard parts that I carry (sailors are nuts in this regard) but now no spark at all. It turns over fine but no spark. I am going tonight to check my install of the above parts. I will let you know. thanks "