Honda BF25 Oil Light flickers

Have a 2000 Honda BF25 outboard that the oil warning light constantly flickers. As the engine revs it continues to flicker, but does so faster, as if its keeping rhythm to the motor. I checked the wiring and it looks nice and clean. I haven't checked grounds yet.

Do these lights normally either stay on or stay off? Is the flickering something mechanical or likely electrical related & false alarm?

Any help would be appreciated where to check next.

This is NOT a comprehensive check of your oil pressure indicator. I don't have the manual for your outboard.

The oil lamp should be ON, bright green and steady when the engine is running.

You could try disconnecting the yellow wire to the switch and see if the flickering stops.

If it does, and the lamp lights green and steady, try removing the switch and flushing it out with
WD-40 or other spray solvent. Use a piece of wire to make sure the oil passage it screws into is clear. Re-install, connect the wire and see what happens.

If the light still flickers, the switch may be faulty or the oil pressure is not as it should be. The oil pressure should be checked at this point. If it checks good, replace the oil switch.

Good luck and let us know what you find.

Thanks. Seems a reasonable way to diagnose myself. I'll give that a try.

The oil pressure listed in my BF 20 D service manual is 21 psi. But there is no elaboration as to if that is at idle or higher. I'm assuming it's an idle spec.

Good luck.

Finally have the boat back from the cottage and starting to do some diagnosis. Took the pressure sensor off and cleaned it, but the light still flickers. I then disconnected the yellow wire completely, and the light still flickers. You mention the switch may be faulty if the light still flickers, but wouldn't disconnecting the yellow wire from the switch eliminate the possibility of a faulty switch?

Any idea what to check next? I don't have an oil pressure gauge (yet) but I'm thinking this may be electrical related based on above?

Ok, here goes.
I looked at my BF 20 D shop manual. They don't do a great job of explaining the oil pressure warning system strategy and Can't access my outboard at the moment to check a couple of things. So, I'm winging it here.

It seems the OP switch is normally closed??? Maybe you can verify that with your meter?
Of course, they don't discuss a flickering light.

I agree with you that it might be a wiring problem.

All I can come up with is to suggest unplugging the CDI and look at the socket and pin (blade) for the yellow wire. I would try using some special, tiny picks I have to clean the pin and socket by giving them a gentle scratch. You could try using a straightened paper clip with the very end bent over 90*. Then use small needle nose pliers to twist the blade slightly to obtain a snug fit. You have to be careful here not booger up the connector.

Check all the blades and sockets of the connector assembly while you're in there.

Give the oil pressure switch connector the same treatment.

Also, check at the lamp connection and see if you can find anything amiss there that could be contributing to a loose connection.

It's also possible the lamp itself is bad.

Good luck.

Well, after reading what you wrote about the light still flickering with the yellow wire unplugged....it CAN'T be anything to do with the yellow wire! Sorry, I hope I didn't send you on a fool's errand.

I should have asked you in the beginning if your outboard is pull start only or electric start. There is a fundamental difference between the two as far as the oil pressure indicator is concerned.

Let me know.

@jmgo - Really appreciate your insight - you really helped me out a lot. I have the Honda Service Manual and I agree, it doesn't go into a lot of detail, although the wiring diagrams were helpful.

This afternoon I took apart and inspected all the wiring connections. I swapped the light with a working one off my 15hp and it too flickered. The CDI is sealed with wires hanging out instead of a connector. Wiring all seems clean and ok. I read a couple other people talking about faint lighting on their small Honda motors so I started to think it might just be the way it is. Of course my main concern is that the oil pressure is ok, the switch is in fact working and that if I ever lose oil pressure that the "flickering" light would go completely out. I used my multimeter while the engine was running and touched both the screw and the side of the oil pressure sensor mimicking the switch closing and the light immediately went out.

So other than the annoyance of the light flickering at low speed, and speeds up to a near solid colour at high speed I feel safe that the engine itself is working properly, and the oil pressure sensor will continue to alert me if there are problems.

Anyone disagree?

Weli, I congratulate you on your ability to take a practical approach and attitude toward what can be described as a minor "nuisance". And, as you say, the switch is working and, it would appear, the oil pressure seems to be adequate. I also agree that the light and switch are still working to the degree that, if you lost oil pressure, you would still be alerted.
So, all in all, I'd say you're good.

But......I have to admit......that if it were mine.....

Having it doing that would drive me BANANAS!

2 STROKES.......

4 STROKES.......


Differnt strokes fer differnt fokes! ;<)

Oh, don't get me wrong - it drives me nuts too and I'll continue to research and hope to find a solution. But at least for now I know its not a mechanical issue with the motor and I can start to use it.

The only part I know of that I was unable to check was the CDI and I'm not sure replacing that to fix a flickering light is a good investment. Maybe there's electrical interference in the CDI thats causing the flicking or something - not sure.

If I figure it out I'll report back to ensure this thread is complete.

Interesting comment I found in a Used Honda Outboard Buyers article. While mine is CDI, the wording almost seems like it hasn't been resolved entirely.

The oil pressure light should be glowing away a nice green, if it's not you have problems. The older engines with Contact Breaker points have a distinct flicker to the light, so don't be alarmed too much by this - it will improve as speed increases. The newer CDI types are better at this.

Yes, that's interesting but I do think you have to look at the breaker point engines and CDI with an "apples n oranges" degree of thought. Although...both are powering that lamp with alternating current....so......hmmm.

I agree I would need to think twice or thrice or fours or more before popping for a new CDI to solve a flickering light. I could be convinced to ignore it in that case. But wasn't there a time it didn't flicker?

If it were a breaker point engine I would look immediately at a new capacitor but big difference in cost.

The reason I asked (you didn't answer) was your outboard electric start was that, in the wiring diagram I have for the 20hp, it lists more connectors in the harness. More connections, more points to check for resistance. Just something to keep in mind while trying to figure it out.

Good luck