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Rober8hp

New member
Hey all

firstly thanks for letting me join the forum.

I am looking for information on outboard rpm.

I have a 4 stroke Honda BF8D teller outboard. I have just fitted a tachometer
To the motor just to get a ball park on rpm but initially for hours of use
Calculation. But now I have become very interested in the rpm.
There are a few settings on the tachometer unit but at idle in a bucket
I get with setting 1: 680 to 700rpm setting 2: 1260 to 1340 rpm setting
3: 14000 rpm

My owners manual does not show idle rpm but on the internet I found something that showed 900 rpm +/-50

Does anyone have any advice? I know that these units are not the most accurate but now I'm curious. Will idle in a bucket show higher rpm?
 
Hi,

Welcome to the forum.

The D model Honda twins (8D, 9.9D, 10D, 15D and 20D) do well at 900 rpm. I always say they "like 900 rpm" for an out of gear idle setting.

But many owners will set the idle a bit lower to slow troll and that can work. So 800 rpm might not be too low as long as the engine doesn't stall or "chug" when it's put in gear. I wouldn't set my 20D that low though.

It shouldn't make any difference if you set the idle IN NEUTRAL in a trash can. Idling the engine in a trash can while it's in gear might pull the rpm's down more than in open water though. Just a guess as I haven't really done any experimenting with that.

Good luck.
 
Thank you for the advice. I'm hoping that my idle is out because of the cheap aftermarket tachometer. Iv ordered a better one as at full throttle at sea it was reading 2670rmp

But I did have other issues this is the email I'm sending back to you service place



My Honda 8hp was serviced at ............... on March 1,2022 on engine sticker it shows 03/03/2022

I finally got time to get the wee little inflatable out on the water. But after less than 30 minutes of slow running at 6 knots the motor started spitting and choking like poor fuel supply. But everything was connected and not restricted at all. Had to row the boat back to the boat ramp. Where I pulled and pushed on the spark leads as the carburettor looked like it was operating as it should. The motor then started but when throttle was applied for acceleration the motor choked and died. I fiddle with the wiring again and it started so we applied acceleration and the motor did not die. Thinking it was all good I headed back out. Before long we started having the issues again. When we got it all back up and running we headed back in.

Fuel line: not obstructed primer bulb hard fuel line connection at motor snug and good condition.
Fuel tank: connections tight and vent open
Motor fuel in filter and when at idle sounds fine.
Choke not out
When engine starts to stall the oil light flashes green then engine dies.

Electrical issue?


Back at home the engine did not start easily. when we tried to flush the motor noticed that the tail water line/ water check hole nothing was coming out all the time it was very week and at times stopped altogether.

Do you have any recommendations?

Please see attached picture of past service invoice

Invoice number

The last service was a full major service is over
 
Hi Rober8hp,

Sorry you're having problems with your Honda. I don't see an attachment with your post so I will ask some questions...

Was the outboard giving problems before you took it in for service?

Did you purchase it new or used? Is this a recent aquisition?

Can you tell us the frame serial number for your outboard? If you don't have that, do you know what model and year? Or, approximately how old it might be?

The more background info you can provide the better.

From what you have described, the outboard sounds as if it might be overheating but I am not 100% sure about that without knowing the model.

You say that the green oil light comes on and goes out. It should not be doing that even if it is overheating. The green oil pressure lamp should come on almost immediately after the engine starts and then it should remain illuminated as long as the engine is running to indicate adequate oil pressure. So, I don't understand why that is occuring.

I think that, initially, we should concentrate on why the waterpump tell-tale isn't working correctly.

Did you pay to have the waterpump serviced? If so,how long did you run the outboard before it started having issues and you noticed no water from the tell-tale?
 
Hopefully the attached photos will appear this time. But water pump has just been replaced it's second hand new to me but less than 30hrs
 
Last edited:
Hi,

No pictures. Most of the time when people have problems loading photos to this site it turns out that the files are too large. Try downsizing to 60% or 40% of original.

If your outboard ran ok before the pump work you may want to take it back to that shop and politely complain about what it's doing before too much time goes by.

Good luck
 
Yes iv emailed them about the situation. It's the first time ever that this motor has had any issues other than maintenance and a shift rod that disconnected. Changed the the size of the pictures and it worked thank you.
IMG_07062022_190425_(1080_x_1111_pixel).jpgIMG_07062022_190149_(1080_x_1080_pixel).jpg
 
Ok,
After looking over the work order I have a couple of observations and another question or two:

From the frame serial number, this outboard appears to be an early 2000's model that hasn't had much done to it because of low usage. Correct?

And this waterpump impeller replacement is likely the first that has been done?

If the above is true then I believe that your engine has indeed been overheating.

Please understand that I can only give you my BEST GUESS and offer you my HONEST OPINION as I am too far removed from your situation for me to do any better than that. So please keep this in mind when I offer my SUGGESTIONS as to what I think is happening.

The shift shaft being disconnected tells me someone, probably a rookie, took off or, attempted to take off, the gearcase to maybe try and address a problem? Would you know anything about that?

The fourth line of the invoice says "Honda Impeller Water Pump".
I believe that is where a BIG mistake was made.

It is my OPINION that this outboard should have been fitted with more parts than just a new impeller. See items 4, 5 and 6 in the link below.

https://www.boats.net/catalog/honda/outboard/8hp/bfp8d1-lhsa-2001/water-pump-vertical-shaft-l-s-size

I don't know why this wasn't done but it's usually because the additional parts up the price by 3X just what the impeller costs. So, often, the customer will turn this very essential part of the repair down. Or, the shop, for whatever reason, doesn't offer this as an option. Either way, it's too bad because not repairing the waterpump properly can lead to disaster for the engine.

The water pump isn't just a set of vane arms whirring around throwing water up a pipe to cool the engine. The pump is actually a fairly sophisticated item that consiststs of the impeller, a metal "cup" to firmly hold the impeller, a plastic housing to firmly hold the cup and a metal plate for the impeller to sit on and wipe against. It only takes ONE loss of prime event of just a FEW seconds time to destroy the efficiency of the pump. If that happens, all those pieces I've outlined are typically overheated and, thus, compromised.

So, the demise of the engine can draw near when a pump is damaged and just the impeller is replaced. The impeller grinds against the damaged walls of the cup and cover. The cup bounces around inside the distorted housing and more heat is QUICKLY generated causing more and more damage while less and less water is being delivered to the engine.

What's worse is that, despite the engine protection shut down provided in the CDI, the operator continues to run the engine. Sometimes to destruction. This is understandable, to a degree, because he's out in the water, trying to get home and can't understand why this da#&ed outboard keeps turning off!!!

I urge you not to run your outboard any more until a very close examination of the waterpump is done.

Just my opinion.

Good luck.
 
Thank you again for a very informative and in-depth analysis of the problem. As far as I know the outboard has only ever been in for required maintenance. The shift rod was only noticed as an issue after the motor was in storage for some time as it was only a seasonal used engine of a 3.4m Rib for summer use. I do agree with you that more should have been replaced. Not to sure why it was not as cost was not the concern. Just wanted the motor like new.

I'll give the service place a week to two for a respond to my email. Hopefully they will respond with a good way forward.
 
Hey Jgmo

The service center has taken the motor back for an in-depth assesment. Hopefully they sort it out. I dropped it off 2 Days ago. So will wait and see.


I'll let you know the outcome.thanks again.
 
As you suggested Jgmo

The motor did over heat. The impeller had a broken fin and due to the heat the housing is now completely damaged. They going to replace the impeller and housing (water pump kit) not sure what all is in it.but they say the damage is not covered by there warranty because the outboard was flushed with flush muffs occasionally. Apparently these motors should not be flushed with muffs. I use a bucket at home and muffs maybe 10 times including at the ramp. they going to do the installation next week then run the motor for a while to see if it over heat's. And check for further damage.

But they are expecting us to pay. I thought that I would wait for the final report and see what was said.
 
Well, I can't say that I am surprised by this development. Outboards are flushed successfully thousands of times every day on muffs. For people with large boats and huge outboards docked in saltwater marinas, muffs are the ONLY way they have to flush their outboards! Many here on this forum use muffs to flush and have had their outboards for years.

So, it makes me wonder about 2 things...

1. Is this "policy" of theirs CLEARLY posted in their shop and on their repair documents?

2. Do their other customers, especially the ones docked in salt water marinas, know about this "policy"? If not, perhaps they all should be told.

At any rate, Rober8hp, I can't litigate this for you. The truth is, I am not a big fan of using muffs myself. But I have used them many, many times and not had any problems. Muffs are just fine for flushing if used correctly.

I just hope that it turns out your engine suffered no damage because
of a failed waterpump.

Good luck.
 
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