Logo
Click for Honda Manuals, Parts and Model Guides!
Results 1 to 12 of 12
  1. #1

    Question Honda BF 9.9D engine run fine then stall at idle

    Hi,
    my outboard runs fine after it warmed up. However, occasionally it stalls at idle after running at high RPMs for a few minutes. Sometimes, it runs at high RPMs at start then it idles down during warm up. I took it to my mechanic and he could not replicate the issue that I was having. The outboard was recently service with new filter and impeller by local outboard shop. I also just replaced the fuel line, and carburetor. What could be the problem?
    TIA,
    Ryan

  2. #2
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,454

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    What year is your outboard?
    Have you owned it since new or did you buy it used recently?
    Why did you replace the parts? IE:carb and impeller.
    Were these items replaced in an attempt to solve these symptoms?

    I ask so many questions because I would like to try and help but need more information than you've provided.

  3. #3

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    Quote Originally Posted by jgmo View Post
    What year is your outboard?
    Have you owned it since new or did you buy it used recently?
    Why did you replace the parts? IE:carb and impeller.
    Were these items replaced in an attempt to solve these symptoms?

    I ask so many questions because I would like to try and help but need more information than you've provided.
    Hi, thank you for your response.
    I believe the motor is from 2003 even though the previous owner said it is 2012. Serial number doesn't come up in Honda website, which is from 2004 forward.
    I recently purchased it. I had it service in Feb of this year after I bought it. The imepeller was replaced by the mechanic as part of the service. I replaced the fuel line and carburetor a couple weeks ago hoping it would fix the issue, but apparently it hasn't.

    I also forgot to add that after it stalled recently, I have to give it more gas for it to start again. Not sure if this is related to the fuel pump.
    Thanks

  4. #4
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,454

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    Hi tyc21ac,
    If you can provide the frame number I can probably date the outboard for you.

    I suspect that you may be experiencing more than one fault with the engine but, for now, we will concentrate on the stalling issue.

    Since it starts and runs at high speed I doubt that the fuel pump is causing the problem but anything is possible.

    It sounds more to me like it could be getting hot. Even though the impeller is new, it may still not be moving enough water at higher revs. I almost never recommend replacing just the impeller. Instead, Honda sells a complete water pump kit that should be used if there is ANY wear to the old one. It costs more than doing just the impeller but it ensures that the pump is good to go for at least 3 seasons or more.

    But, in this case, I think that you may first need to focus on the thermostat. Since it's a used unit, I recommend replacing the thermostat right off rather than trying to test it. Chances are that the previous owner neglected replacement. Most people don't do a very good job of monitoring engine temperature and thermostats rarely ever get looked at. This is even more of an issue if the outboard was primarily operated in salt water.

    You will know as soon as you take the Tstat cover off. A "salty" will typically have a white, powdery look to the engine metal and possibly obvious evidence of the passages being clogged as a result. Careful cleaning would then be in order to try and remove the mineral deposits without removing and damaging the aluminum of the engine casting.

    Dosing the outboard with white vinegar solution by running it in a bucket or trashcan can help break down the deposits somewhat. Then brushing the areas that you can reach with a stainless steel bristle as well as very careful and MILD scraping can help too. But you have to be very cautious not to clean too aggressively because the minerals embed themselves in the metal and taking too much can be harmful. It boils down to you have to just settle for what you can safely remove.

    With the thermostat out and the lower unit removed the passages can be "backflushed" to clear any debris that may have lodged in the passages using shop air and full home water pressure.

    I'm assuming that this is a tiller steer since the remote would have warning lights and a buzzer and you didn't mention them.

    Let me know what you think.
    Last edited by jgmo; 05-28-2020 at 02:39 PM.

  5. #5
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,454

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    Forgot to mention that you might try disconnecting the wire at the water temperature sensor and see if the stalling goes away. This would support my theory that the CDI is seeing localized heat spikes via the sensor.

    If you do try this it defeats the warning system and engine protection so you need to be very watchful of engine temperature. An infrared temp gun aimed at the cylinder head can be very helpful while trying this test. Of course, you would need to have the cover off to do this.

  6. #6

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    [QUOTE=jgmo;682990]
    I just noticed that there was fuel coming out of the exhaust after it stalled. You are probably right about many issues with his motor.

  7. #7
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,454

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    Fuel out the exhaust? That's odd.
    Are you positive that the correct carburetor was installed? Was it purchased from Honda? I hope your mechanic didn't sell you something he sourced off ebay.

  8. #8

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    Yes, it is very odd. When I test the engine out at home; it can run for over an hour with no issues. The mechanic said the same thing when he was testing it in his water pool. However, when I take it out into the ocean and put it on more stress, especially in rough water, it would stalled when I shift to idle quickly from running and fuel is leaking out from the exhaust.
    yes, the carburetor is genuine Honda part based on Honda website.
    I just ordered a new thermostat. I removed the old thermostat and it is clean, but it seems to start opening at higher than the recommended temp by Honda, 140F. Hopefully, that'll fix it.

  9. #9
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,454

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    Are you sure that it is fuel coming from the exhaust? These exhaust systems are cooled by the water that cools the engine and it is normal to see a bit of residual flow of water as the engine comes to a stop.

    And yes, the problems will more readily show up as you fully work the engine. It has been said that pushing a boat with an outboard at top speed is like driving your car up a mountain constantly.

    I hope the new stat makes an improvement.

    Good luck.

  10. #10

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    Jgmo,
    you are an awesome mechanic!!! I tested it out today, it works great with new thermostats!
    Maybe I was wrong about fuel, it could be water that mixed with some oil residue from the exhaust.

    Why do you think it idles fast when I start the engine, it would slow down to idle speed after 30s-60s?

    Thank you so much!

  11. #11
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,454

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    Your engine is equipped with a system called "fuel enrichment". It is to help it get going when it not up to temperature. It should idle higher when first started and return to normal idle in about 1 minute or so. Sooner if it has already been started and shut down for a little while.

    What you're describing sounds as if the system is operating in a normal fashion. Let me know if you disagree.

    Otherwise, happy boating and fair winds to ye!

  12. #12

    Default Re: Honda BF 9.9D engine run fine then stall at idle

    I'm new at this. Thank you for your input. Much appreciated!!!

Similar Threads

  1. Engine runs fine at idle but stalls when giving gas...
    By seymour064 in forum Mercruiser Sterndrive Forum
    Replies: 6
    Last Post: 06-15-2016, 12:04 AM
  2. Engine stall from idle to fwd (sometimes...)
    By mlawson in forum OMC Sterndrive and Inboard Forum
    Replies: 4
    Last Post: 08-23-2014, 08:30 AM
  3. Replies: 4
    Last Post: 07-23-2014, 11:49 AM
  4. Replies: 4
    Last Post: 08-17-2011, 03:35 PM
  5. Replies: 5
    Last Post: 05-14-2009, 11:28 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •