Model year 2000 Honda BF15a 4-stroke won't start. Historically it has always started on the second pull, even after many months of no use. Problem started immediately after motor got pretty hot when it stopped passing water maybe 1/2 mile from destination. I've since removed the impeller fragments, replaced the impeller, and flushed out the water system, including removing the thermostat and running water directly into the engine as well as through the thermostat tube. (Thermostat not stuck, moves easily with moderate thumb pressure.)
Starting: Have worked through shop manual troubleshooting procedure:
-- Spark plug looks wet and smells gassy, not fouled or oily.
-- No spark visible, even in the evening, when I do the spark test, even with new plug and used but OK old plug.
-- Stop switch seems OK: no continuity when switch open (engine run position, with little spacer key in slot in red button), continuity when I remove the key and switch closes (to kill the motor).
-- Brightened up the metal tabs on the cam pulley; the little magnet they pass by seems strong, as do the flywheel magnets.
-- Got varying readings when checking the CDI (with two different multitesters) -- I don't have one of the special testers called for in the shop manual.
-- Have checked and rechecked, unplugged and reseated all the various connectors.
-- Exciter coil, pulser coil, and ignition coil secondary circuit resistance numbers all within spec per shop manual.
-- Ignition coil primary circuit a little out of spec. 0.36-0.43 ohm called for; I show 0.9-1.0. Aha. Must be the problem, right?
Measured the coil on a friend's BF15, just for grins. Older model, but same spec for ignition coil primary circuit (I checked his shop manual). His coil, which works, measures 1.0 ohm across the primaries.
What's up? Why would one coil (his) work and the other (mine) not? When the ignition coil fails, does the primary develop greater resistance, or break and show no resistance? Or does the problem lie elsewhere? If so, where? I've checked and measured everything. Would the engine's getting quite hot have contributed to the problem? Or just coincidence? What to try next?
Starting: Have worked through shop manual troubleshooting procedure:
-- Spark plug looks wet and smells gassy, not fouled or oily.
-- No spark visible, even in the evening, when I do the spark test, even with new plug and used but OK old plug.
-- Stop switch seems OK: no continuity when switch open (engine run position, with little spacer key in slot in red button), continuity when I remove the key and switch closes (to kill the motor).
-- Brightened up the metal tabs on the cam pulley; the little magnet they pass by seems strong, as do the flywheel magnets.
-- Got varying readings when checking the CDI (with two different multitesters) -- I don't have one of the special testers called for in the shop manual.
-- Have checked and rechecked, unplugged and reseated all the various connectors.
-- Exciter coil, pulser coil, and ignition coil secondary circuit resistance numbers all within spec per shop manual.
-- Ignition coil primary circuit a little out of spec. 0.36-0.43 ohm called for; I show 0.9-1.0. Aha. Must be the problem, right?
Measured the coil on a friend's BF15, just for grins. Older model, but same spec for ignition coil primary circuit (I checked his shop manual). His coil, which works, measures 1.0 ohm across the primaries.
What's up? Why would one coil (his) work and the other (mine) not? When the ignition coil fails, does the primary develop greater resistance, or break and show no resistance? Or does the problem lie elsewhere? If so, where? I've checked and measured everything. Would the engine's getting quite hot have contributed to the problem? Or just coincidence? What to try next?
