91 Yamaha 250 No Spark

[Salty Dog]

I have an old Pursuit with twin 91 250 Yamahas. Last time I had it out it ran fine all day then the port motor cut out. It would sputter and die like it was running on 3 cylinders.

The next day it sounded like it wanted to start but then nothing. I used a spark tester and got no spark to any of the plugs.

Anyone have some tips on what or where to look first? I have a winky blinky light and a multi-meter.

Thanks

 

[rodbolt]

Re: 91 Yamaha 250 No Spark

test the kill circuit, white wire to black.
then test stator charge coil output. the CAREFULLY test the pulser coil to ground.
that motor uses left and right bank charge coils.
lose either and lose a bank, lose both and both banks quit.
however the pulser coils,all 6, share a common ground lose it and lose all6.

 

[Salty Dog]

Re: 91 Yamaha 250 No Spark

Thanks rodbolt

Can I jump the white and black at the engine or does it have to be done at the key switch?

 

[rodbolt]

Re: 91 Yamaha 250 No Spark

the white needs to be unplugged from the black. then test white wire to ground,should have an open circuit.

 

[99yam40]

Re: 91 Yamaha 250 No Spark

never mind, Rodbolt already replied

 

[Salty Dog]

Re: 91 Yamaha 250 No Spark

After some testing we found one bank had no spark.

We swapped the ECU from the starboard motor and she fired right up!

Thanks for the help