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Old 09-04-2017, 11:48 AM   #1
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City: Wherever Smartini is
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Vessel Model: 2002 Kristen 52' Flybridge Trawler
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Genset fixed, finally?

Long time, no posts. It's been busy here on Smartini. But I wanted to brag a little...

Last December, our genset suddenly wouldn't run without the pre-heat / shutdown bypass switch being held on. Two hours of head scratching by a genset tech later, I just installed a hotwire from the battery to the fuel rack solenoid, and was able to use the generator on our Christmas trip to the Abacos. Right after we returned, we hauled out for what was supposed to be a few weeks, but stretched into 5 months. (So no need for the generator, and no way to run it to try to fix it.)

Back in the water in June. Traced the problem to a wire that used to go to a genset console at the flybridge that had been removed a long time ago. It's apparently grounded somewhere, so it acts like one of the shutdown circuits (coolant overheat, exhaust overheat, or low oil pressure). Removed that wire from the circuit, and all was great! For a few hours.

Had another tech onboard - this time, a certified Northern Lights tech - who traced the problem (which was now intermittent) to a diode that feeds power to one of the relays that was cutting out intermittently. Replaced the diode, and all was great! For a few days.

I wasn't going to have time to dig into it again for awhile (guests onboard), so I hooked up my hotwire again and just hoped I didn't suck something into the raw water intake while all of my shutdown circuits were disabled.

Two days ago, with guests gone and a determined spirit, I got out the schematic and spent about 3 hours documenting every part of the start / run / shutdown circuits (each with its own relay). Then I designed a test scheme for each "state" (no switches on; just the shutdown bypass switch on; just the start switch on; both switches on), that I could test with all the relays removed.

Shortly after I started testing (how did I ever get through life without a multi-meter?), I found one of the sockets for the Run Relay that didn't have 12v when it should have. Removed the socket, and sure enough, there was a recently-replaced diode - with a broken wire on one end. My NL-certified professional did a pretty crappy job of putting that diode in place.

An hour later, I had rewired his connection, and now, I think I'll have a properly working generator. Why, oh why, is it so hard to find someone who knows what they're doing, AND cares enough about their work to do it right?

On the bright side, I now have an excellent guide to troubleshooting my genset, and more to the point, I actually understand how all those relays work.
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Old 09-04-2017, 01:56 PM   #2
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One more reason to learn your own systems.
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Old 09-04-2017, 05:13 PM   #3
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Nice job sorting it out and learning how it works. And I share your frustration, as do many other people, with so-called professional trades. Some are very good, but they seem to be few and far between.
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