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2018 225's

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Pistolerocaptain

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Have twin 225 Honda outboards. Starboard has been only problem. For last month or two upon acceleration the check engine alarm goes off and revs drop. If I put it i neutral for 3-5 seconds the alarm goes off and I can resume normal operation. It's only occasional and it doesn't matter if motor is cold or warmed up. During acceleration it'll sound continuous alarm and cut revs. It's under warranty so service techs have come and diagnosed as O2 sensor and replaced it three times. Problem keep coming up though the port engine is still on original O2 sensor.
 
Did the service Tech's hook up Dr. H or the HDS diagnostic computer to the service connector to see what codes are being thrown? If not, they should have.

How far do the rev's drop off - to about 1800 rpm?
 
chawk_man said:
Did the service Tech's hook up Dr. H or the HDS diagnostic computer to the service connector to see what codes are being thrown? If not, they should have.

How far do the rev's drop off - to about 1800 rpm?
Click to expand...
They drop to about 1100 rpm. They have twice used a laptop diagnostic computer and both times said it was the O2 sensor. replaced both times and problem reoccurs within a few days to months. Other engine is still on original sensor.
 
Interesting!

A failed HO2 sensor should not drop rpm's. It only makes the engine run rich, and degrades efficiency. Did the Tech's happen to pull the plugs to see if they were covered with black soot? That would indicate that the engine was running too rich and the HO2 failure was likely the cause. If the plugs had a normal light brown coating, then the HO2 was not likely the problem.

Did the Tech's happen to check the fuel pressure at idle? It should be between 42 psi and 49 psi at 600 rpm idle with vacuum hose to the fuel pressure regulator removed and pinched closed. Fuel pressure out of spec can also give a fault code like a failed HO2 sensor.

Based on your posts, I would suspect that you either have an intermittent fuel flow problem OR a flaky ECU. A flaky ECU should have thrown other codes, too. But you never can tell.

FYI: Overheating will drop the rpm's to 1800 and then shut down the engine after 20 seconds if not remedied. Low oil pressure will drop rpm's to 1800, but the engine will continue to run.

FYI 2: I am not a marine mechanic - just an owner of a BF 225 who tries to do all of my own maintenance, diagnostics, and repairs.
 
�� I am not a marine mechanic, but I have 5126 posts only.
Very impressive, imagine how many posts you would have had if you were a marine mechanic.
Still I am impressed with CHawk and it proves that you are passionate.
Me too I am passionate with my Honda, I have the paperback shop manual I read allot, but most of all I am truly impressed by non mechanics removing cylinder heads and doing serious repair work considering they see themselves as “non professionals “.
I myself know the BF130 well since I had one ,the BF250 Ist (new to me) I have a fair understanding of it but don’t really know if I would trust myself to remove the cylinder heads or do major tear downs.
 
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