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Honda 2005 225hp starter engages without a key on

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bethron1

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I have a 2005 BF225 with 120 hours that over the weekend the starter engages with the ignition off and the key out. The boat was up on a lift out of the water and all of a sudden the starter engages and cranks the motor over for 5 or 6 seconds. As a quick fix I disconnected the battery cable and installed an inline battery switch. The problem has now progressed to the point that when I turn the battery switch on and apply battery power (in neutral) the starter engages but won't start the engine...however the engine will start as soon as I turn the ignition switch on. With the engine running in neutral the starter stays engaged until I put the shift/throttle into gear or move the throttle slightly forward to disengage the neutral switch only to engage itself again when in the full neutral position.

From what I see from the Honda service manual, the main relay engages the starter and the ECM(computer) feeds the main relay. Either of these two could be faulty. Anyone have similar experiences with the starter engaging on its own.??? My second thought is a faulty igniton switch itself. Thanks to those who offer suggestions.

2nd problem.
I had a faulty spark plug which had an intermittent miss so replaced all the plugs. Noticed that all the plugs has a slight black carbon built up at the base instead of the usual grayish color. Would a faulty O2 sensor cause the engine to run rich enough to cause this carbon built up on all the plugs. This engine uses way too much fuel and the plugs would suggest this too. Is this O2 sensor an automitive sensor or unique to a marine application. Anyone have a part number?? Thanks
 
Re: Honda 225 starter engages without a key on

Starter engaging when battery powered. Suprisingly, this could be related to your HO2 sensor. In your fuse box, there is a 30 Amp fuse on the right side. That fuse supplies both the HO2 sensor and the starter motor solonoid, among other things. Remove the fuse, clean the contacts thoroughly, look for any broken or fried wires, and replace the fuse. There should be a spare in your fuse box (bottom right.)

If that does not help, then you simply need to go on a bug hunt. I would start with the switch. With battery disconnected, try spraying a little bit of WD-40 into the key slot and run it back and forth a bunch of times. Then reconnect to see if that fixed the problem. Next, there should be (but not always) a connector where the wiring harness plugs into the key switch. Disconnect that, and see if that fixes the problem. If so, then you will need to replace the key switch.

If that does not help, then disconnect the wire harness that comes from the key switch to the motor, at the motor. That is a round, 14-pin connector. If that stops the starter from engaging when powered up, then you likely have a short or other problem (corroded prongs?) in the wiring harness to the key switch. That means the harness will likely need to be replaced.

HO2 Sensor - Yes, a faulty sensor will increase fuel consumption and cause the carbon build up. As far as I know, that HO2 sensor is unique to the BF 225. Several folks on this forum have looked for an automotive replacement, because they are so much less expensive. But I've not heard of anyone who claims they have found one that works.

General observations. You have a 2005 BF 225 with only 120 hours? That's an average of 20 hours per year. First, that engine is not even broken in, which is bad for you and the engine. You need to run at WOT as much as possible over the next 100 hours or more in order to properly seat the valves and rings. (At WOT that engine will eat 20 gallons of fuel per hour, but it's worth it.) That alone could be the reason the the carbon build up on the plugs. Secondly, I suspect that the lack of use has contributed to carbon build-up. Consider de-carboning the engine using Sea Foam or Yamalube Ring Free. Third, thoroughly review your maintenance procedures. Because the engine has so low usage, lots of subtle things can go wrong, especially with the fuel system.
 
Re: Honda 225 starter engages without a key on

Here's an update to the problem. Turns out the main relay assembly was bad. It's a sealed unit so I have to speculate what really happened. The relay that the 30a. fuse feeds to shorted applying 12 volts to the entire engine even when the key was removed and given enough time would run the battery down. The red Alt. light would be on with no key inserted.
Now, I left the boat up on a lift for the afternoon and while away it appears one of the diodes in the main relay broke down and shorted out applying 12 volt starter power. The starter spun the engine for who knows how long and after a time litterly melted the starter and neighbors thought the engine was on fire for all the smoke. So long story short, starter and relay had to be replaced and all is fine now. I thought that the impeller was going to need replaced since it was spinning out of the water but it seems to be cooling OK and the pee stream is solid, but will replace it anyway next spring. Honda says too bad.
 
Re: Honda 225 starter engages without a key on

Happy to hear you got it fixed. I would be very leery of the water pump situation. If you have any time at all, change it out. In this case, I would change out the entire pump, not just the impeller. It's not that much more than the kit, and it will be worth the peace of mind.
 
Re: Honda 225 starter engages without a key on

Interesting post, as I have twin 2005/2006 BF225 that have 250 hour a piece on them and have had a similar situation strike. The starboard engine powers up as soon as the battery switch is turned on, without a key (hell even disconnected the whole wiring harness). Foruntately mine does not try and start. After tinkering all day I had come to the conclusion that the main relay had lost its mind so I am glad to see this has occured before. I am curious where you were able to get your part as I am having a hard time finding it thru the online part dealers and the local honda dealer is a couple of hours away.
 
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