Not Getting Spark - 1997 Royal Star
This may, unfortunately, be rather lengthy; once you understand how your ignition system works, you may be able to troubleshoot it yourself. I am going to include a few places to check to streamline the troubleshooting procedure as well.
The coils function by having a constant battery voltage on the red/black wire (you'll notice that ALL the coils have a red/black wire) - the primary windings in the coil charge up, until the ignitor "grounds" the colored wire (grey and white in the front, orange and yellow in the rear). As the voltage in the primary winding drops to zero, it creates a strong magnetic field - the magnet (laminated iron) in the center of the coil passes that magnetic field to the secondary windings, which turn the field into voltages of between 35,000 and 65,000 volts, and those very high voltages fire the plug.
Not so hard, right? Unfortunately, there are a few things that can keep ANY of that from happening. Sooooooo...
1. Start by removing the gas tank, so that the coils are available for testing with a voltmeter (and yes, a little Radio Shack $9.99 cheapie will be adequate for any of the testing I'm going to cover). I prefer to use the coils for the front cylinders, simply because they're easier to get to with the tank off. Turn on the ignition key, and check the red/black lead on the coil most convenient to you - the voltage should exceed 9.5 volts (it's usually much more than that, but 9.5 is plenty), if so, skip to 2. If it's a little less than 9.5 volts, check the terminals on the coils to make sure they're clean, and check the charge of the battery. If the voltage is a LOT less than 9.5 volts (like 0!) we have some checking to do to see where it went. If the battery is good, remove the left side cover (underneath the driver's seat) and check the 30 amp main fuse, and ALL of the 10 amp fuses in the box (the ignition fuse should be identified in the lid, but if the fuse labels are obscured or missing, check all five of them - three should have battery voltage on both sides [ignition, clock, and radiator fan], the other two are spares). Replace any that are blown, check voltage at the coil again, ignition on. Still no voltage? Next, check the engine stop switch; flip from one position to the other, checking for voltage on the coil in both positions. If the voltage is absent in both positions you have either a broken stop switch, a broken wire between the ignition fuse and the stop switch, or a broken wire between the stop switch and the coil(s). The wire from the ignition fuse to the stop switch is red/white, and the wire from the stop switch to the coils is, obviously, red/black. You can split the housing that holds the engine stop switch to check the leads at the switch itself, but you'll have to disconnect the throttle cables to get to it; make sure you examine the routing of the throttle cables before disassembling, so they can be properly reinstalled. If you have voltage on one side of the switch, but not the other, the switch will have to be replaced.
2. Turn the engine over while checking voltage on the colored lead attached to the coil (grey and white in the front, orange and yellow in the rear), the voltage at that lead should drop to 2.5 volts or less. If it does, the engine should start once the fuel tank is hooked back up and the carburetors are primed. If not, check to make sure that all modular connectors are clean and firmly seated in the ignitor. Check to make sure that the neutral light is lit, then check the resistance through the pickup coil (you'll see a modular connector at the ignitor with one grey and one black lead, the resistance between the leads should be 189-231 ohms. If more or less, replace the pickup coil. Last, look for a modular plug with a blue/yellow lead and a light green lead, a continuity test with the positive probe on the blue/yellow lead and the negative probe on the light green lead should show an open circuit, reverse the leads and the tester should show continuity. If the test is not correct, replace the starting circuit cut-off relay. If the diode tests good, the ignitor will have to be replaced.
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