[Roger2]

Hi Guys:What can the home mechanic do to systamaticly trouble shoot a motor that has an intermittent problem. Let me explain. Here are some of the symtoms.1. Gas bulb is soft every morning.2. Cylinder #1 plug is fouled and looks like it's flooded with oil and has carbon deposit on 1/2 of smooth bottom of plug. 3. Engine would not start. Removed kill switch.I now get motor to start every time but only runs on (2) cylinders.4. Removed (3) plug wires, (3) coils and switch box and had local mechanic bench test. He said they are all OK.5. When I reinstalled all components the engine started fine on all three cylinders.6. Problem came back the next day. Started motor in morning when it is cold and only runs on (2) cylinders. #1 is not firing. Remove cowling cover of motor and #1 cylinder started to fire. Though the problem was in the spark plug wires but I have not been able to dublicate removing the problem. Problem came back. 7. Just removed the cover from the motor and the problem went away. Checked all the wires and can't find a one that is shorted. Intermittent short comes back when engine is cold. Just raising and lowering the engine has caused problem to go away.How do I trouble shoot:1. Stator. 2. Trigger. 3. Switch box. 4. Coils. 5. Wires.Is there something inside the switch box that gets reset every time you turn the engine on or off?Please help with a step by step instruction for troubleshooting. I made up a grounded screwdriver and went around looking for shorts but could not find one. Bought a $10.00 dollar spark tester and yes I do have spark and I don't have spark coming to the #1 coil. This leads me to believe that I have a trigger problem or a switch box problem. Help-----Help-----Help.How do you trouble shoot these parts.Thanks. Roger2

[poppopfishes2002]

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[Bear]

http://outboardparts.com/mercury/mis...ootinghelp.htm Buy a manual too.Good luck!

[petryshyn]

if you can get it to missfire, check the 3 trigger voltages at the pack. If they all read the same > bad PACK.If you find one thats low > triggerAlso try swapping the coil leads (primary and secondary) and see if the problem follows.Sounds like a typical pack failure.....but check the trigger and coils first.

[rickdb1boat]

Sure sonds like there is a short somewhere, as when you take the hood off, it runs OK. Or when you raise or lower the Motor it runs good. Check ALL the Motor compartment wiring and just Outside off the Motor, where they enter the cowl.

[steelespike]

Some kind of a short or a poor ground.There is a slim chance of an exhaust leak underthe hood could be killing the air quality.