Honda BF15D 2008 engine oil light of or flickering

Hello Again !

3 weeks later and i have use the engine for more then 40km (25miles).
Technically the engine runs perfect.
Oil light is working and after the oil change the light lid up after 2 seconds because the oil filter had to be filled.
So the system actually works that is very nice to know.

Also i have serviced the complete engine with all the original honda parts.
It runs on first or second pull.

Thank you for your tips and tricks, and yes, i agree to see that honda is very reliable and simple to work on.
The other day my friend had a little overheating problem with his new suzuki 30hp. The engine went to 'emergancy run' (dont know what its called)
He had to go to the dealer to reset the system. Also i personally dont like the injection system yet. Easy and simple is what i like

btw i didnt burn my hand on the pee stream, but yes it was hot indeed hahah.
Okay now i have another question wich i hope can have an easy fix this time.

Engine runs perfect.
It is used on a cheap rubberboat, i think you guys call it a SIB. It has a removable aluminium floor.
The transom height is 15 inch / 38cm
the outboard height from mounting arm to cavitation plate is 17.3 inch / 43.3mm

As far as i know the cavitation plate should be on the same level of the transom lowest point


My speed without any adjustments is 34km/h - 21 mp/h.
Without adjustments, the lower end of the engine makes backwash, it throws a lot of water back in the boat.

I have ordered and installed a 3 cm / 1.18 inch stainless steel bracket to elevate the engine a little bit.
if possible i dont want to go any higher because the clamps of the engine are near the top of the official transom (the actual wood)
With this higher engine the topspeed is the same. But the backwash is over. No more backwash.
When the engine is trimmed in the most upper position (furthest from trnasom) the engine takes air
When the engine is trimmed in the most down position (closest to transom) there is a very little bit backwash.

Basically it is all fine now.
But..... i really would like to have a little bit more speed.
I used to have a honda 8hp on the same boat wich did go 28km/h - 17.3mp/h
The difference in speed between 8 and 15hp is just too small in my opinion.

Today i have sailed together with another person. He had the a slight smaller boat (suzumar 340) with a B brand 9,9hp (Hallmarine).
We did have the exact same speed. I think that i should be faster with the 15hp. yes i know it depends on a lot of factors but all in all i think at this moment my outboard underpreforms.


My questions:
Is it better to make a new and bigger stainless steel bracket wich makes the engine even higher in the water.
I have the original 4 blade prop on the engine now. Some people tell me this is working prop for bigger vessels. Any idea's?

I will post photo's and video's below
The prop that is on now is 9-1/4 x 10
4 blade

Video above: engine tilt in position 4 (1=near transom, 5 is furthest away)

Video above: engine tilt in position 3 (1=near transom, 5 is furthest away)

Both with max throttle











The pictures below are WITH the stainless steel riser installed.




The cavitation plate is aprox 2cm below the transom lowest point.




When viewed this way the cavitation plate is on the same height as the lowest point of the complete boat.
The front of the boat is lower and angled

Splash is generally (almost always) due to the engine being mounted too low.

4 blade prop is fine as long as it prevents decent performance without allowing the engine to over rev at max throttle.

Hi Killerbean,
In the very last photo your outboard appears to be much too low. The cavitation plate (the one just above the prop) should be level, or near so, with the transom's lowest point at the center line of the keel.

In that photo it appears that the "splash plate" (the plate just above the cavitation plate) is approximately where the cavitation plate should be positioned.

It could be that raising the outboard that small amount will give you a bit more speed and less splash. I would definitely try that if it were mine.

But you might still not be satisfied with the speed increase as I predict it will likely be slight. Honda does make a three bladed prop for this outboard that would provide less drag going through the water but, again, the speed gain is likely to be small.

Consulting a prop manufacturer for prop diameter and optimum pitch changes for achieving the highest performance is something you might try but experiments with propeller changes can be very expensive as well as disappointing.

I wish I had a solution for you in my pocket but I don't.

P.S. we call them RIB (for "Reenforced Inflatable Boat") over here;>)

Hi Guys back to the original problem, as far as I recall from the last Hondaoil light problem I looked into the brief summary of the system is.
Light is lit green when oil pressure is good
Engine must be running for it to be lit (although you should be able to rig up some wiring to test it)
Engine must be running because the light is powered (Dc AFAIR) from the CDI so the engine needs to be running for the coils to produce AC which is rectified and sent to the CDI which then has a power feed to the oil light
The next condition to illuminate the lamp is of course the oil pressure switch being triggered to show sufficient pressure to illuminate the oil pressure indicator.
I can’t recall if the pressure switch is open or closed circuit arrest but this can be tested by removing the pressure switch (after draining the engine oil), hook up an a o to the tail and body (earth) the see what the resistance reading is, push a bit of compressed air into the switch where the oil would go in (don’t go too mad with high pressure) and you should see your abo switch from pen to closed circuit (or vice versa)
If the pressure switch is functioning correctly hook up to the indicator light connectors on the engine side with dv voltage connected and check the output at rest and then with the engine running.
cheers

Hello Everybody

First of all is there maybe an admin that can change the topic title? Something like it is now with the engine height adjustment. I see that i cannot do that anymore.
Im sorry for messing up the SIB and RIB part

Thank you for the reply's. I have been away for a few days but i did some testing in between.
With the previous stainless steel system (photo's above) the cavitation plate still is 1 inch below the lowest point of the transom.
Please know that the splash plate is near the PVC edge. The black PVC is glued to the rear of the transom.
But with the stainless steel mount i still have a little splashing when in plane with the engine trimmed down (near transom)

So in the days later a borrowed another engine. B brand Hallmarine 9.9HP purchased new last year.
The engine height/cavitation plate height was the exact same as my honda 15hp. The problems where also the same.
My honda 15hp did go 21mph
The hallmarine 9.9 did go 16mph.

I just purchased some 2mm and 3mm stainless steel plates and will make my own transom higher. it will raise around 2.5 inch total wich should bring the cavitation plate to the same height as the lowest point of the transom. I will write here what difference i will notice.



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About the oil light:

Yes Tony you are correct. When the light is on (green) the oil pressure is fine.
Yes the engine must be running for it to be lit. The engine produces current wich will make the light shine.
I have posted above the values that i measured with the light working. It was around 118v AC i believe.
I have only tested the wiring itself with the engine off to see if the wiring itself was okay.

My rectifier is NOT connected to the CDI in any way. my rectifier is a standalone unit that doesnt work at this moment.
As far as i know the AC current from the flywheel goes to the CDI unit.
And most important, the circle has to be completed for the light to be lit. If any system (CDI/light/pressure sensor) is broken, the light wont lit.
The oil pressure sensor is a simple on/off switch wich can be easily tested. Engine ON system is closed, Engine OFF system is open. Or vice versa. You get the point.
I was unable to let any light shine from my new green light. I tried different battery's and small AC current. It would only lit when it was fully connected to the system.

I never removed the pressure switch to test it. It was done within 60 seconds. Use the multimeter and measure the center pin of the oil pressure sensor and get the negative from the outside of the sensor , the nut. It didnt matter for me how much volts there where, the oil pressure sensor is just on of off. 1 or 0.

After the oil change i started my engine, it took 2-4 seconds for the oil light to lit. This is because the oil filter was empty so there was not enough oil pressure.
This is how i know that the complete system now actually works instead of just the light that is burning.

I hope this helps you tony, its difficult to explain some things in english.
The new light wasnt cheap but they do fail every now and then.

I can post the wiring scheme if you like but its an easy system.
1 wire from oil pressure sensor to CDI
1 wire from CDI to oil light
Negative from oil light to ground.

P.s. easiest start is to clean all the bullet connectors, they can be corroded.

Hi Killerbean,
You are a very thorough and determined owner! I believe you will eventually maximize your RIB's speed.

As far as I know, the heading of your post is "locked in" and can't be changed. But you should be able to start a new thread using your preferred headline. I think that's a good idea and will, hopefully, get more people thinking about the outboard mounting and trim as they relate to speed.

One thing to also keep in mind is what I call "operating angle". The angle that the boat hull presents fore to aft will have a bearing on hole shot and ultimate speed. If the hull is riding with the bow too high at "take off" or when trimmed in then you can see that the transom will be too low and can effect the efficiency of how the prop pushes the boat. Sometimes it's as simple as loading the boat differently with crew and gear. I always kept a tiller extension on my little jon boat so I could sit further forward when I was alone. It made that little hull go MUCH faster than it would with me plunked down on the stern seat. Just something to think about.

I don't think Tony Outboard was asking for assistance but was trying to explain how the system works. I was thinking about pointing out to him your voltage test readings myself. I am interested in what he has to say about that since I was somewhat surprised by them and how they contradict what the service manual suggests.

It wouldn't be the first time my (and other's) testing of Honda electrical components weren't in agreement with shop manual specifications.

In your particular case, you were methodical and, I believe, accurate in your tests. In addition, you had success in that the new lamp assembly worked. One thing no one can argue with is success;>)

Here's hoping your new mount gets you that increase in speed.

Cheers!

Thanks for your reply Jgmo.
Sorry for missing the point of Tony. It was not my fault, it is weekend here...
Yes i know exactly what you mean, i do have an tiller extension too. I always sit down when sailing fast. The V hull is 'sharper' that way so i wont get air pockets.

I will make a new topic soon about the transom height and share some pictures.
Thank you for your compliments. In my country they call me stubborn sometimes. I rather see it as a 'feature' hahah.
Have a great weekend.

Cheers
Sander

I see it as a "feature" too!!
Hahahahahaha!