1989 90HP 3 Cyl Mercury No Power Production On Number 1 Cylinder (STUMPER)

This is another posting regarding the same problem.<br />S/N OC162559 1989 90HP Mercury 3 Cylinder, Single Switch Box System (Thunderbolt V Maybe).<br />I have lost power production on number one cylinder. No change in RPM when disconnecting NO1 plug wire during idle or any power setting along with an erratic (stumbling) idle.<br />Disconnecting NO's 2 or 3 results in a 400-500 RPM drop.(at idle)<br />I have 125 PSI Compression on all 3.<br />Carbs are clean and clear inside on all three.<br />No signs of bad seals at carbs, air box, reed valve assembly.<br />Switched coils around No2 to No1 and No1 to No2 with problem unchanged.<br />Attempted carb adjustment, No affect on engine performance when tweeking the NO 1 carb idle/mix screw.<br />I also did a visual on the reed valves, all looked clean, clear, and fine. I gently opened the valves individually with a pencil using the soft eraser end and they opened and closed easily. I have ruled out the fuel delivery system.<br />Electrical Update:<br />When testing the trigger coil for resistance values the number one coil (violet wire) tested slightly low on OHMS 940 to be exact. Specs call for 1100 to 1400.<br />The voltage created by the winding is only .4 volts A/C less than the others(1.20 versus 1.6 Volts A/C on 2 and 3) under cranking.<br />Question?<br />Before I pull the trigger coil and repalce it, can this small difference in resistance and voltage be enough to cause the secondary circuit to fail when attemting to fire the plug under pressure? The spark looks crisp and blue at the spark plug lead when held near ground and the timing light works AOK when checking the timing using the same NO1 spark plug lead.<br />Stator resistance checks are GOOD, I don't suspect this component because the stator is a common A/C output coil to fire all three cylinders.<br />What is the most Likely culprit, the trigger or the costly Switch Box?<br />Is there anyway to further troubleshoot the Trigger or Switch Box without an Oscilliscope Analyzer?<br />I was going to attempt switching trigger inputs to the switchbox, and switchbox outputs around to have the switchbox trigger the cylinders in the same firing order using the differing transitors and capacitor. Can this be done without "SMOKE CHECKING" the switchbox?<br />Your infinite wisdom is greatly appreciated.<br />ANCHORS AWEIGH.<br />PS I wonder if Roy Rogers had this much trouble with TRIGGER.<br />THANKS<br />Wild Will

Re: 1989 90HP 3 Cyl Mercury No Power Production On Number 1 Cylinder (STUMPER)

Roy Rogers was actually a paid promoter of Mercury, as well as a fan.<br /><br />Yes you outta be able to switch around the trigger wires and/or switchbox wires to narrow it all down. <br /><br />If it's *not* electrical it could be a stumper that somehow points to a broken reed - easy to check on those.<br /><br />-W

Re: 1989 90HP 3 Cyl Mercury No Power Production On Number 1 Cylinder (STUMPER)

You have'nt described to us what runability problems you are trying to solve.These engines are loop charged and consequentally shake rattle and roll across the lake at idle.They also do not respond as expected to the spark drop test you have given.Are you just chaseing you're tail?

Re: 1989 90HP 3 Cyl Mercury No Power Production On Number 1 Cylinder (STUMPER)

NO POWER from No 1 cylinder under all power settings. Runabilty (power production loss) as described in earlier posting. Dramatic power loss shortly after throttling up on plane after a hard start episode. Currently runs erratic on muffs at idle during troubleshooting.<br />BTW the only tail chasing I do are tails that wear skirts.<br />Thanks<br />WildWill