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2021 Honda BF50D above 3000 rpm engine stops, warning light MIL and alarm

M

Mac26x

New member
Below 3000 rpm the engine worked well. Above 3000 rpm the MIL light and a repeating alarm came on and the engine stopped. I could start immediately but the same thing happened if I went over 3000 rpm.

I found a similar issue but a broken link (Post of Aug 13, 2013) sent in by Isandboy123 but unfortunately the link was incomplete and therefore I don't have the solution.

I have cleaned the Low Pressure fuel filter, replaced the High Pressure Filter, which was filthy, drained the engine completely (vapour tube, fuel filters, raised and lowered engine while draining fuel, turned ignition on to drain more fuel). I have drained the fuel tanks, cut off the ends of the fuel lines to ensure no air leaks, filled with fresh fuel. Are there any needles that have sediment/particles and are plugging fuel delivery. checked the thermostat and it opens and closes when in hotwater and then removed. Installed a new Impeller service kit.

As well, I changed the oil and filter, new plugs, lower gear oil change.

The result is that now when I go over 3000 rpm, for example 3500 rpm, the rpms can drop to 2500 rpm and the either bounce back to 3500 rpm or return slowly to 3500 rpm. The engine is hot and has been placed in a large bucket. Only the acceleration handle is utilized to change rpm.

I feel confident that the fuel I purchased prior to the problem was contaminated.

Any suggestion would be appreciated. Tomorrow I will test the gas tanks for an air leak.

Cheers
Alex
 
Hi,
Since you mentioned that you were pretty sure that you purchased contaminated fuel, I might suspect some debris may have made it into the fuel injectors.

I've never worked on one of these engines but I know that most, if not all, injectors have little filter screens that can clog.

I would also wonder about what may be lurking in the fuel supply tube for the injectors. See item 3 in the link below.


And I don't know but am wondering if item 4 (joint, fuel pipe) might have a filtering screen in it?

Just an idea.

Hope you get it sorted out.

Good luck.
 
Not to say it's not a fuel starvation issue but the fact that the engine runs well up to 3k.rpm then the alarm followed by shut down might actually be pointing in another direction. Or, indicating that you may have more than a single problem.

If you can't find a "smoking gun" cause, you may find it necessary to have the Dr.H diagnostics hooked up to help figure this out.

It can be very difficult to diagnose one of these EFI engines without the use of that tool.

Hope you get a fix.
 
An example of what I was getting at would be something amiss with the oxygen sensor. That could cause very similar symptoms to what you're experiencing but hard to diagnose without Dr.H.

Just read a post about a 225 that was acting up surging and dying in a similar fashion. He reported that he needed to replace his ECM due to a bad connection for the O2 sensor.

Just tossing it out there.

Good luck.
 
Thanks again. I feel like this path is going way beyond my skill set, but I don't disagree with your diagnosis. O2 sensor would make sense, too. I'll see what I can do, but I'm getting closer to taking the boat to a Honda mechanic.
 
Well, I was just trying to help you brainstorm. More guessing than diagnosis.

I do think it's wise to get help if you need it but I always worry about the quality of work done at many shops.

It's likely your most critical effort in getting your outboard fixed is going to be vetting the facility you take it to.

Hopefully you already know of a good one that you can trust.

Please update with what happens. It could be very helpful to someone else here in the future.

Wishing you the best.
 
The mechanic utilized Dr. H and determine that the Oxygen Fuel Sensor malfunctioned. We reset the error and all appears to be working well.
thanks for your help.
PS After cleaning/replacing fuel filters etc. you may want to reset the sensor and see whether the Oxygen fuel sensor actually needs replacement or the error was do to sediment in the fuel that caused the Oxygen Fuel Sensor to send error messages.

Thanks for the help
 
Well, that's very interesting. I have never heard of an oxygen sensor "reset" or that fuel sediment could cause an O2 sensor to malfunction.

But, then, you could build TWO new worlds from what I don't know....for SURE!

I'm glad to hear you've got it running good again. And, not to be throwing out "negative waves" but I do hope the "fix" is a lasting one.

I would certainly be interested in hearing back from you in a while about how she's running.

Thanks very much for updating your post.
 
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