Generator- Co detector and blower link

Absolutely Nothing said:

I have a a "new to me" 2004 Marlin equipped with a FP generator. With the generator come a CO detector and blower unit in the aft bilge. I replaced the CO detector as it appeared that the old one was the original (over 10 years old) and not working. The new one is not getting power and the blower does not work. Is there a fuse that supports both the blower and CO detector? Where would it be located? Any other ideas that might help? I have tried with the generator running and not running with no change in the CO or blower performance. Thanks for any help you might provide to this newbie to the forum.

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If your gen set is gasoline powered then starting without first using the blower is extremely dangerous. The blower is there to purge any gas fumes that might be present. If the genset and supporting equipment are not explosion proof turning it on could ignite fumes. The CO detector is not critical for starting but is for running. If there is CO present you won't know and that could be fatal.
I would expect a manual switch somewhere for the blower and that circuit would be powered off the main breaker/fuse panel although your installation could be different if not OEM. The CO and blower could be on the same circuit or they could be on different ones. The power for the CO detector can not be connected off of the switched side of the blower circuit. It has to be 'live' whenever general vessel power is on, regardless of the blower being on or off

So, if the generator is gasoline powered and not explosion proof, you could be putting your life at risk without the blower purging. This situation needs to be dealt with ASAP.
Safe boating!

It looks to me, from looking at my schematic, that the CO monitor get it's power from the generator control panel. If the generator panel is not switched in the on position when you're checking, you will not get a reading. The blower is turned on with a breaker on the AC/DC panel on the DC side, so you must have the main Aft circuit breaker closed and the DC main at the panel closed.

I forgot to mention that if your blower isn't working, you can open the generator access panel, let it air out and sniff with your nose for gas fumes. If none, it is usually safe to use the gen set

After looking further at the schematic, there is a 1 amp ATO fuse for the CO monitor using 16 gauge Red/Black wire. Where? not sure....

To add to the above... a CO monitor should have a constant 12V supply. Even if the engines and battery switches are off. The reason for this is to protect anyone sleeping in the cabin, regardless of any engines running, or not. It can get it's power from any, always hot, lead - which also means it will have it's own, inline, fuse. I haven't looked at newer Grady wiring schematics, but if they're like other top-notch builders then the schematics will be very good and all the wires will be coded to match the schematics so you can easily identify them. As far as following wires, start with what was mentioned above as hopefully there weren't any major changes to this area from his model year to yours.

Dennis, It is my understanding (I could be wrong!) that without the generator package, you usually don't have a CO monitor, at least from Grady. It is there because you could have a problem with an exhaust leak and, because the generator is below deck, the exhaust could fill the bilge and make it's way into the cabin area. The #1 bank needs to be switched on to run the generator. I saw two references to the CO monitor in the "One Line" drawings. One showing the CO monitor directly connected to the Generator control panel and one to a 12V supply showing the 1 amp fuse. They could be different views of the same. Not sure. But, if you think about it, why would you need a CO monitor if you're not running the generator? The fuse could be between the control panel and the monitor and either be fed intermittently when powering up the panel or fed from a 12V supply when you turn on the battery switch to run the generator. It will be interesting to find out!

You definitely bring up a good point about the genny/no genny vs CO detector thing. I can only answer from having experience with multiple, "cabin/cruiser" style boats. While those were all stern drives or inboards (gassers), and of course had CO detectors, the detectors were ALWAYS hard wired. I've seen this in many other cabin/cruiser style (including go-fast boats) as well, although I didn't personally own them.

I think the idea is that... as an example... you're in your boat sleeping while in the slip with everything turned off. Your dock neighbor has his genny running and the exhaust floats into your boat and into your cabin. You don't wake up.

If a boat happens to have a butane or alcohol stove, that's another reason to have a CO monitor. Possibly using a portable heater is another reason to have a CO monitor - which would obviously not be an issue with a bow rider.

As another example... I've personally had the CO detector's alarm sound after working in the cabin for an extended period of time (happened twice). The door was open, but the boat was shrink wrapped. Now, I don't fully understand this since I don't exhale CO, I exhale CO2. But, none the less, it did happen. Just can't explain why.

So, while I don't know whether it's "required" by USCG for an outboard with no genny, I do think it's a good idea. And, from my experience, anytime there has been a CO monitor installed by the factory (regardless of boat brand), it has ALWAYS been hard-wired -- which was my main point to you -- look for a hard-wired connection (of course, maybe Grady does it differently than every other manufacturer I've seen so far!). The other stuff is really just a "side note" for discussion.

All valid points and certainly a smart choice for sure but I think the CO monitor on Gradys is part of the generator package. My last two Gradys did not. Because of the examples you've brought to the table, maybe those that don't have one should consider it a near future project.....

The Wiring table in my manual lists this -
"CO Detector 16 ga. Red/Black 1.0 Positive bus (in line) / 336 console fuse block".

So I guess the first place I would look is the fuse block under the dash and look for a 1 amp fuse. There can't be many or even any other things using a 1 amp fuse.

On my 2007 330, the CO detector is powered anytime the house battery switch (STBD) is powered. The blower is also on that same buss. Not sure where the blower CB is located, but the blower switch is on the generator panel and works regardless of generator status, on or off. I always run the bilge blower for several minutes before starting the generator.

journeyman said:

The Wiring table in my manual lists this -
"CO Detector 16 ga. Red/Black 1.0 Positive bus (in line) / 336 console fuse block".

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That's some good info for the OP. With what you have found and what Spitler has said, a safe assumption would be that his gets it's power from the same source as most manufacturer's try to keep things as standard as possible across the line-up of models... or at least whenever possible.