FJ40 Rebuild

Tuesday, July 24, 2007


once you start, you cant stop

my dad was coming up the next day to weld the steering components and help finish up a few other things, so i was trying to wrap up everything else. the last thing i wanted to get done was to finish flushing the cooling system. i had flushed it a few times already and this was going to be the final time. i started up the engine and let it run for about 10 minutes. then i turned the key off to shut off the engine and...nothing happened. the motor just kept running as usual. i turned the key back to ON and then OFF again - nothing. i turned it over to the accessory position - nothing. i finally grabbed the coil wire and pulled it off the distributor and the motor died.

after doing quite a bit of research, i discovered that an internally-regulated distributor will actually feed power back up the exciter wire and keep the coil powered, even when the ignition is off. the fix is to either wire the exciter wire through a dashboard light, or install a diode in the wire - in either case, it only allows the power to flow one-way and solves the problem. so, i made a quick trip to radio shack and picked up a diode and a fuse holder. as i was checking out, the radio shack clerk said 'lemme guess, motor starts but wont turn off when you turn off the key?'. guess i was not the first person to run into this issue =)

here is the diode i used

i bent the diode wires into a spiral to form the rough shape of a fuse

once bent up, the diode fit in the fuse holder perfectly

i plugged the fuse holder/diode into the exciter wire, started the engine, switched the key back to OFF, and the motor died - problem solved.