Yamaha 2 stroke 70 HP 1996 - Ignition coil resistance

[Melbournite]

Just trying to confirm the OHM resistance measurement for the ignition coil.

Have measured the primary coil resistance (Black/White -Black) and get 0.9 on coils 1, 2 & 3
Have measured secondary coil resistance (Black/White -High Tension Cord) and get 4.61 to 4.64 on each coil.

I think the secondary coil resistance is within spec but primary coil seems high as spec shows 0.18 - 0.24. Motor has been cutting out under load after about 5-10 minutes on water but doesn't repeat the problem when testing on land. Could the high primary coil resistance cause this to happen? Or is it possible another component is causing this?

 

[tommarvin]

Melbournite, You the man, a perfect approach to all ignition problems, TEST before ya GUESS. This is what you do next man, Go to cdielectronics.com click your make, year,HP, part example power pack. Scroll down there's trouble shooting and testing for every ignition part they sell. These guys are the king of ignition parts,I think Iboats sells cdi electronics now? It's all there, but a little overwhelming.

Free factory service manuals at www boatinfo.no/lib/library.html click your make,find your motor,find the page your looking for. Never buy coils from e-bay.

If a ground is loose or disconnected, or a wire is grounded out, no expensive ignition part is going to help, give every wire a tug, especially that go inside connector,they love to break inside, so you can't see them.

E-bay has a DVA Ignition tester for 100 buck, if that will help.

 

[99yam40]

I would not think all of the coils would go bad at the same time and same way.
Probably just the meter leads resistance added in with the coil resistance.
not all meters are good at measuring small resistances accurately.

Follow the steps in service manual for testing the ignition system components.
a special meter for these ignition systems is needed to be able to compare the specs in manual or use a DVA adapter with your regular meter to read peak voltages.
Yoou might want to make sure your alarm system /buzzer works, because it may be going into a alarm state and you do not know it . If you have a good tach it should have indicators on it also that would show what is going on if it is a alarm condition

 

[Melbournite]

Thanks for the advice, have got a copy of the manual so have the specs needed. Just need to get the DVA adapter to do the other tests. I did check the alarm system in boiling water and it did come on. Will let you know how things go.