2000 Honda BF75 Starting and Acceleration issues

[Boater_TAT]

I have a 2000 Honda BF75 outboard with the 4 carburetor setup. The motor has been good, in general, but there are some glitches that I cannot seem to fix so far, by myself. I am curious to know if these are common issues with this motor, or if I should bring the motor in to a certified Honda mechanic...

1) When starting the motor when it is cold, I cannot just push in the key to choke the motor and have it start. Instead, I need to do that, "and", take the motor out of gear and push the accelerator forward to push more fuel into the carbs. Is this normal? If not, is this something I can solve on my own (I am fairly handy and have done quite a few things on vehicles and motors.....)

2) When running the motor and accelerating up to cruising speed, the motor will bog down and kill at 2000 RPMS. I have to slowly play around with the throttle to slowly approach and attempt to get past the 2000 RPM mark. Once I successfully navigate past this 2000 RPM mark, the motor accelerates and runs quite normal. If I slow down and then go back up again, it usually will work fine while the motor is warm (perhaps one more bog down, but by the third time it is fine.) This works fine until I shut the motor off and let it sit for 1-2 hours. Upon starting the motor and running again, I will have the same issues at 2000 RPMs.

I have been told this is most likely a carburetor problem. Can something confirm this? If so, do I need to bring it to a shop for cleaning and repair? If not, what else should I look at for resolution?

Thanks for any and all comments/help.... I am hopeful I can solve this without a costly mechanic visit

 

[Boater_TAT]

Re: 2000 Honda BF75 Starting and Acceleration issues

OK, an update. I have done two things. 1) I have tore the engine apart and cleaned the carburetors. They were spotless, so that is not the issue. #2) based on forum research, I have found that there was/is a known issue with acceleration stability of the Honda carbureted engines "previous" to June 2000. At that time, Honda changed the dashpot solenoid and CAM - Throttle opener in acknowledgement that the fuel mix was too lean for rapid acceleration. So, I believe I know what parts to swap out on the motor, but my new question is:

Q: How do I determine the "month" and "year" that my motor was manufactured? Model is BF75, year 2000. Number stamped on the unit is BBAL-4200382 and the engine block number is BBAE-2001363.

Can someone help me figure out what month this engine came off the assembly line? I hesitate to spend the $100+ in parts if I already have the newer versions.......

Thanks

Todd

 

[o/b tech]

Re: 2000 Honda BF75 Starting and Acceleration issues

Hi Todd,

I have just recently worked on a 2001 75 Honda and a 1999 45 Honda. Carbs are clean and set up with vacuumate gauge. I've set up the accelerator dashpot in every possible position and both motors still bog and spit and cough during hard acceleration. I'm trying to find out any info that may help this situation. Any info on updated parts would be greatly appreciated.

Thanks.

 

[MattFL]

Re: 2000 Honda BF75 Starting and Acceleration issues

@Boater - It is normal to have to give a cold carbureted motor both throttle and choke to start it. It's also normal to have to continue choking and giving a little throttle to some carbureted motors to keep them going until they warm up a bit, especially motors that are jetted lean for emissions reasons. It is also normal for a cold carbureted motor to bog with sudden throttle opening. Cold engines don't burn fuel as efficiently and need a richer mix to run smoothly. The carburetor doesn't adjust the mix based on engine temperature like a fuel injected motor will so some carbureted motors will act lean until they are up to full temp, that is normal. Once it's up to full temp it should run smoothly with no bogging.

If it's full temp and you get a bog and suspect it might be due to a lean condition, then try this. Open the throttle and when it bogs tap the choke as quick as you can. It will cut out while the choke is on, but if it then suddenly snaps to full power the instant the choke is off then this more or less verifies that you've got a lean condition.

 

[Boater_TAT]

Re: 2000 Honda BF75 Starting and Acceleration issues

Quick Update on my research:

In the electronic version of my boat motor service manual, on page 350 I found a Service News Bulletin. It indicated that on June 2000, Honda updated the diaphragm-related parts to "improve the acceleration stability." The parts listed are 1) valve - dashpot solenoid, 2) diaphragm assembly, 3) spring, assist 4) CAM - throttle Opener and 5) tube, fuel (not sure why this was listed.)

I ended up calling Honda Marine to determine when my 2000 75 HP motor was manufactured. It came off the assembly line on January 18, 2000. So based on the service news bulletin, my motor has the outdated diaphragm related parts. I also confirmed with the Honda Marine help desk specialist that the parts in question did change in 2000. He looked them up and indicated that their part numbers did change in June of 2000, so that would indicate an updated version.

So, I have come to the conclusion that I need to purchase these parts if I have a chance of getting past this acceleration issue. I will be making the order soon and have the engine back together in a week or two. Unfortunately we are approaching the winter months here in MN, so not sure the boat will get back in the water until spring; so won't be able to verify the fix until it does.........

@MattFL - thanks for the clarification on carbureted motor starting, etc. Very much appreciated!

Here is the service manual page:

 

[MattFL]

Re: 2000 Honda BF75 Starting and Acceleration issues

great! Be sure to let us know what happens. Also out of curiosity, have these motors always behaved this way since you bought them?

 

[Boater_TAT]

Re: 2000 Honda BF75 Starting and Acceleration issues

In my case, yes; some years worse then others. I bought the boat from my brother-in-law back in 2004. He had put on less then 10 hours on the motor and used it primarily for fishing activity. In my case, since I did not have older kids, I only used the boat 2-3 times per year for fishing trips as well. I have always noticed the hesitation (and sometimes outright killing) of the engine at 2000 RPMS. 4 years ago it was terrible, and I was convinced it was carburetor issues, since I left fuel in the engine (without draining the carbs) over winter. I spent the next 3-4 trips with the boat working on "burning" out the varnish in the carbs with double doses of fuel stabilizer etc. I thought I had made good progress and the motor seems to hesitate "less" after this. I then got very good at draining the carbs if the boat was to sit for more then a week...

However, now my kids are at the age where they want to tube and ski. Unfortunately, the engine issues at 2000 RPM are much more noticeable now. Plus, I just finished a fishing trip up north where the temps were in the 40-60 degree range, and I had to constantly deal with the motor killing. So much so that I hoped to come home and trade it in. But, cooler heads prevailed and I starting working on resolving the engine issues; since Honda has a great rep.........

So, hopefully the diaphragm/accelerator pump part replacements will do the trick. Its the best solution I have found to date (especially since I called two dealership and they both wouldn't even walk through the issue with me.)

Stay tuned........

 

[MattFL]

Re: 2000 Honda BF75 Starting and Acceleration issues

In my personal experience, old gas can contribute to this. I store gas every storm season so I've had some practice at it over the years, and I find that gas with ethanol really degrades. I try to put all of the stored gas through the boat over the winter but lately I've had some left that is about a year old when the next storm season starts. I'm noticing that the gas with ethanol that is a year old runs noticeably worse than new gas. The idle is rough, acceleration is a little off and it just doesn't seem to run nearly as smoothly. As soon as I get fresh gas in the tank it all clears up. If you've constantly got old gas then that might be a contributing factor. Also since you're in colder temps, try replacing the thermostat. If it's stuck open and the motor runs too cool, that can definitely contribute.

 

[Boater_TAT]

Re: 2000 Honda BF75 Starting and Acceleration issues

(UPDATE: I started a new discussion thread. Didn't mean to bury this question.) Quick question for any Honda motor mechanics or guru's out here on the engine forums......

I am getting ready to swap out the Throttle CAM components for my 2000 carbureted motor; to improve its acceleration reliability (based on information already shared above.) One of the main components is the dashpot valve. In researching parts at ********** I noticed that the part listed for 2000 is a "dashpot solenoid value" (part #: 36135-ZQ1-004), but for 2001 (and newer,) it is called a "dashpot check valve " (part #: 36135-ZW1-L01). What is the significant difference between a solenoid and a check valve, and would this be important to swap out on my 2000 engine? Would it work or would I be making a major mistake in engine performance?

Any guidance out there? Thanks in advance!