Recently I inadvertently reversed the polarity of the battery connection to my [unspecified year] YAMAHA 60-HP two-stroke-power-cycle engine. (I know that was dumb.)
After that I replaced the rectifier-voltage-regulator assembly, but the engine is totally dead. It does not start. There is no [power] trim. However, there is battery voltage on the starter motor, on the relay and the on trim.
Q1: is there another set of diodes somewhere else in the engine?
Eric
Kenton on Sea
Yamaha 60-HP Won't Start After Battery Polarity Reversal
Re: Yamaha 60-HP Won't Start After Battery Polarity Reversal
Usually there will be a fuse that protects the loads connected to the battery like the ignition key switch and the remote trim-tilt controls. Usually the fuse will be under the engine cowling.
Your engine status as "dead" suggests that the engine starter motor is not operated when the ignition key switch is moved to START. This could be due to an open fuse under the engine cowling. The fuse is nominally a 10-Ampere fuse.
Also, older two-stroke-power-cycle engines used a permanent magnet alternator (PMA). The PMA has magnets embedded in the flywheel and a stator coil assembly with several winding. With reversed polarity there could have been damage to the coil windings in the stator from excessive current flow in the windings.
Typically the coil winding in the stator are routed to the rectifiers by a cable that includes a connector. You should be able to measure the resistance of the coil windings by opening the connection to them at the connector.
If you are measuring battery voltage on the relays for the power trim, that does not mean the relay coils will have power. The relay coils get their power from the trim switch, and power to the trim switch is usually protected by that same 10-Ampere fuse.
Your first step should be to locate the 10-Ampere (or similar rating) fuse under the engine cowling, and assess if the fuse has opened.
ALSO--If the engine cranks over but does not fire, check the engine-shut-off safety lanyard switch. If the lanyard is slightly dislodged from the switch it will cause a no-start condition, even though the engine will crank over.
Your engine status as "dead" suggests that the engine starter motor is not operated when the ignition key switch is moved to START. This could be due to an open fuse under the engine cowling. The fuse is nominally a 10-Ampere fuse.
Also, older two-stroke-power-cycle engines used a permanent magnet alternator (PMA). The PMA has magnets embedded in the flywheel and a stator coil assembly with several winding. With reversed polarity there could have been damage to the coil windings in the stator from excessive current flow in the windings.
Typically the coil winding in the stator are routed to the rectifiers by a cable that includes a connector. You should be able to measure the resistance of the coil windings by opening the connection to them at the connector.
If you are measuring battery voltage on the relays for the power trim, that does not mean the relay coils will have power. The relay coils get their power from the trim switch, and power to the trim switch is usually protected by that same 10-Ampere fuse.
Your first step should be to locate the 10-Ampere (or similar rating) fuse under the engine cowling, and assess if the fuse has opened.
ALSO--If the engine cranks over but does not fire, check the engine-shut-off safety lanyard switch. If the lanyard is slightly dislodged from the switch it will cause a no-start condition, even though the engine will crank over.
Re: Yamaha 60-HP Won't Start After Battery Polarity Reversal
Thanks for that [reply].
I forgot to mention I replaced the fuse.
I forgot to mention I replaced the fuse.
Re: Yamaha 60-HP Won't Start After Battery Polarity Reversal
Anything else you left out?
Does the starter motor crank over the engine when you turn the key to START from RUN or OFF?
Have you checked for spark voltage? Use an in-line spark gap tester. They are not expensive.
The spark ignition circuitry is typically NOT part of the voltage rectifier-regulator assembly.
Trying to make your own engine repairs will be greatly facilitated if you purchase the manufacturer’s service manual. The service manual will typically include detailed schematic diagrams of the engine electrical system.
Go to the local servicing dealer for the engine. Tell them what you did. Ask them what parts to buy. They very likely have encountered a customer before you who did the same thing—probably several customers—and they will know what electrical components were damaged by the polarity reversal.
Does the starter motor crank over the engine when you turn the key to START from RUN or OFF?
Have you checked for spark voltage? Use an in-line spark gap tester. They are not expensive.
The spark ignition circuitry is typically NOT part of the voltage rectifier-regulator assembly.
Trying to make your own engine repairs will be greatly facilitated if you purchase the manufacturer’s service manual. The service manual will typically include detailed schematic diagrams of the engine electrical system.
Go to the local servicing dealer for the engine. Tell them what you did. Ask them what parts to buy. They very likely have encountered a customer before you who did the same thing—probably several customers—and they will know what electrical components were damaged by the polarity reversal.