2000 25hp Bigfoot 4-Stroke- no spark

[jnbradley3]

This is a console setup- not tiller model.

While trolling at idle the motor just stopped. I knew that was a bad sign because in 13 yrs it had NEVER done that! Indeed, it would not restart. At home discovered no spark in either cylinder.

Can measure near 300 volts(with DVA) off stator at cranking speed. All stator resistance tests are OK. No voltage measured at ignition coil input. Ignition primary coil and secondary resistance OK. Crank position sensor resistance OK.

Continuity checks from stator to ECM, ECM to ignition coil both OK. Checked function of lanyard switch at console-OK ( didn't check wires from switch to wherever they go on engine).

So it appears everything points to the ECM being the culprit....... Since that's a $200+ item I thought I would run it by you in case I have missed something. I've also read mechanics saying that those units are very reliable and usually last on their list of things to check.

Can you offer any other ideas or advice?

Thanks, Jim

[freeportd]

Jim, you've ruled out a bunch of stuff - and the ECM is still on the list of potential culprits - but I sure understand not wanting to buy it only to find that's not the issue. If I were you, I would try to source one as a 'try it/buy it' deal. By that, ask the parts dealer if you can buy it and replace yours. If that fixes the problem, you keep it - and you and the dealer are both happy. If it doesn't, you return it and he still has a good ECU. The chances might be slim that they'll do it - but it's worth a chance.

[boats.net]

Need to test stop circuit to see if shorted to ground. Test trigger coils output to switch box.

[jnbradley3]

Thanks SM for the reply.

By stop circuit are you referring to the lanyard switch? I've rechecked the wiring diagrams now and see that the manual and tiller model diagrams do show where that switch connects to the ECM. Oddly the diagram for my model does not show or mention that switch. So I can check that out- hopefully it connects to the same point.

Trigger coils? There must be a different term for that- there is no mention of trigger coils anywhere in my service manual- neither in the parts/wiring diagrams or the description of how the ignition circuit works. Is this one of the stator coils?

Thanks, Jim

[boats.net]

4 stroke models use a crank position sensor instead of trigger coils.