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BF 20 won't start. Any ideas?

A

Alan M

New member
Hi guys, first post here.
I have a catamaran with a pair of BF 20s, ultra long shaft with high thrust props.

A few days back, the port motor, which had been running perfectly, just stopped. I checked fuel which was OK, drained the bowl on the fuel filter, no water, but no restart either. I let it cool for a while but still dead. It turns over fine, but doesn't fire.

So we motored home on one engine, and I started testing. Pretty soon discovered no spark.

SSo since I had a known running engine, I decided to do some parts swapping to try to determine what was wrong. So far I've replaced: the entire ignition system, rotor, stator, pulse generator, CDI box, coil, leads and plugs. I've also replaced the overheat cut out switch and the oil pressure switch. I even swapped carburettors. The earthing on the coil seemed suspect, so I've wired in new earthing for the coil and CDI unit.
I've also swapped over the ignition switch and even the alarm buzzers. There's no MOB kill switch.

I have also checked compression which seems OK too. It's still dead, just does not fire.
And I'm out of ideas. Anyone have any suggestions?
 
Sorry, I probably asked the wrong question. Getting ahead of myself.

So, starting over.....

To clarify, this doesn't have an emergency stop switch with the lanyard? Meaning, the only way to kill the engine is by switching off the ignition switch?

You say that you've already swapped the ignition switch so that would leave trying to determine if the black/red wire from the CDI is grounded or not.

Remove the connector at the CDI and use an ohmmeter to probe the black/red wire connector terminal and a reliable engine ground. If you find that there is continuity then you will need to find where that wire is grounding in the harness.

That's where I would start checking anyway.

Good luck.
 
Yes, correct, to stop the engine you switch off the ignition.

Thanks, that's definitely worth a look. It's a forward control, so a short to ground in the red/black somewhere in the harness would definitely kill the spark. I'll check that out.

Measuring pulse type voltages isn't great with my digital multimeter. I may have to get an analogue one.

Thanks very much!
 
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