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Blowing O2 sensors

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Skooter

Advanced Contributor
I have twin Honda 200's and my ecm was giving me the "1" code on the mil light, so I replaced my O2 sensor a few weeks ago with a "good" used one and cleared the codes..I took my boat out this past weekend and ran 35 straight miles without stopping or turning off engine. When I stopped and was idling, I started getting beeps and the check engine light came on..I turned off engine and restarted and it was fine idling, until I ran it again and stopped, then it would beep again..I came home and checked codes and have a "1" again...I dont think my outboard has had the newer exhausts put on it, but I did notice that I have about 8 inches of waterline clearance under the exhaust ports (except with following 3' seas). It also is putting out a lot of soot out the exhaust...boat ran great, idled great, but I need some help in figuring out this O2 problem.
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Looks like the motor is burning way too rich, or it's burning oil. Are you getting either black smoke (too rich) or white smoke (burning oil) out of the exhaust when it is warmed up? That "used" HO2 sensor may be your problem. It will cause a rich burn.
 
It's not burning any oil, I changed plugs when I put O2 sensor on, so I had an idea it was running rich...also my fuel burn was a lot more per mile than it has ever been...as for the O2 sensor, I'm sure the sensor is not bad. The outboard that is running rich is my SB side and the O2 sensor came from my port side motor and I put the "used" one on the port motor. So is it possible that my exhaust could ingest water on a long run such as in my case...I have a suspicion that I am going to be doing SB #56 on this real soon..
 
If I understand SB #56 correctly, when the engine is running, it is almost impossible to ingest water through the exhaust tubes due to the pressure coming out of the firing cylinders. With the old original exhaust tubes, the water was ingested into the exhaust into the exhaust tubes when the engine was cranking for start up. So I suspect you may have another problem. The first thing I would do would be a compression test, paying special attention to cylinder # 6 - that's the one that most often suffers damage from water incursion. The next thing I would consider is a good decarb using Sea Foam or Yamalube Ring Free, or similar. Hopefully, other will chime in on this.
 
This is the same outboard that I replaced all the exhaust and intake valves, seals and resurfaced the head on when my timing pulley seized and threw off my timing belt. All the cylinders "looked" good with no scoring and the outboard only had 750 hours on it. I can't help but think that my exhaust pipes may be corroded or cracked. I'm going to pull lower unit next week and I went ahead and order one kit for SB #56 and water pump. I figured it needs to get done anyway. Not looking forward to the corroded/stuck bolts, but at least I know it will be done right.
 
If you are looking for an O2 sensor and this one fits your application contact me. It's brand new but I don't think it's correct for my 2006 BF225XA SN14xxxxx

Honda P/N 35655-ZY3-013
 
Skooter,

I had a similar issue. I thought my engines ran rich so I checked the o2 sensors and then replaced them both. It seemed a little better at first but the fuel burn was about the same. I have had the alarm on my stbd engine 2x now but it does not do it every time. I have a pair of 200's as well. They are 2003's. I am running the original exhaust pipes on mine. I changed the midsections when I got the boat but still can't figure out why I didn't do the tubes then. I cleaned up the old ones and put new gaskets on them. I try to trim up the engines when I am stopping to fish. I slow down with one at a time trying to minimize the rush of water against the back of the engines too. When I get back to the dock and on the trailer, I trim the engines up and rev them a little in neutral to make sure any moisture in the exhaust is blown out. I am not sure if any of this really helps or not. I believe my engines are in the 1k hr range.
I get the black out of the exhaust but not as bad as yours. The only time it was that heavy was after a good decarb. I do get some of that black after each trip though.
Maybe you were loaded up from running rich with the bad o2 before, now it is working and the engine is burning off all that buildup, resulting in the soot.
 
Ep4 said:
Skooter,

I had a similar issue. I thought my engines ran rich so I checked the o2 sensors and then replaced them both. It seemed a little better at first but the fuel burn was about the same. I have had the alarm on my stbd engine 2x now but it does not do it every time. I have a pair of 200's as well. They are 2003's. I am running the original exhaust pipes on mine. I changed the midsections when I got the boat but still can't figure out why I didn't do the tubes then. I cleaned up the old ones and put new gaskets on them. I try to trim up the engines when I am stopping to fish. I slow down with one at a time trying to minimize the rush of water against the back of the engines too. When I get back to the dock and on the trailer, I trim the engines up and rev them a little in neutral to make sure any moisture in the exhaust is blown out. I am not sure if any of this really helps or not. I believe my engines are in the 1k hr range.
I get the black out of the exhaust but not as bad as yours. The only time it was that heavy was after a good decarb. I do get some of that black after each trip though.
Maybe you were loaded up from running rich with the bad o2 before, now it is working and the engine is burning off all that buildup, resulting in the soot.
Click to expand...
Parts are on order for SB56, I'm hoping this resolves my issue..Shark Bait I sent u pm..Thanks
 
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