I have a 1990 25hp mariner (I think it’s a 1990), that when cold it will only run on the top cylinder. The lower cylinder has no spark at the plug. I don’t have a manual, so I’m not sure how to trouble shoot the ignition. I checked at the primary on the top cylinder coil and it shows an off on signal, but the bottom cylinder coil doesn’t. My question is, how do I determine if it is the switch box or a trigger coil.<br />Also I installed (“T” ed in the line) a DVM in the wire coming from the backside of the flywheel and for the top cylinder it shows approx. 70 volts at just above idle, where the lower cylinder shows only approx. 30 volts. As the motor warms up the lower cylinder will kick in, but the voltmeter still reads the same at both. I think that it is a bad switch box, but the low reading on the bad cylinder has me wondering. Maybe this type of a reading has no value.<br />Thanks for any help.<br />Dan
