Honda BF50 hard to start

[Harry van der Meer]

Question for the OB motor experts.

I have a 2001 Honda BF50 that is increasingly hard to start when the motor is warm.

Cold start is fine. She fires up in seconds with full choke open and purrs like a kitten.

However, if the motor has been off for an hour or so, I am having a hard time getting her going. This was sometimes a problem last years but it seems it is worse now.

I do the regular winterizing procedure, draining the carbs and putting some oil in the cylinders. New spark plugs (Honda) at the beginning of the season (May).

I have not done any further investigation, such as spark plug gap, etc. Squeezing the fuel line ball a few times gets it nice and hard, so I don't think there is a leak. Fuel is relatively fresh (few weeks at most).

I read with interest previous postings regarding gumming of the carbs. Would I have this problem?

Would like to get some hints before I start digging deeper.

Thanks.

[Moe]

Harry, define hard to start, please.

Does the starter turn slower than usual?

Does the starter spin as fast as usual but

the engine doesn't fire at all

the engine fires occasionally but won't run

the engine fires and runs roughly momentarily before quitting

if the latter is there smoke in the exhaust

if so what color, white, black, blue?

Do you smell gasoline when having problem starting?

Do I understand it correctly that the motor will restart with no problem perhaps 15 minutes after shutting it off, but won't an hour after shutting it off, but will again once the motor is fully cooled down?

Thanks,

[Harry van der Meer]

Moe, thanks for responding. Answers below.


>>>Does the starter turn slower than usual?<<<
no - not noticeable


>>>Does the starter spin as fast as usual but
the engine doesn't fire at all <<<
yes

>>>the engine fires occasionally but won't run <<<
yes, if I fully engage the choke it will eventually fire up. I don't like to use the choke too much when the engine is warm for fear of flooding.

the engine fires and runs roughly momentarily before quitting
yes


>>>if the latter is there smoke in the exhaust <<<
may be a little

>>>if so what color, white, black, blue? <<<
blue

>>>Do you smell gasoline when having problem starting? <<<
No


>>>Do I understand it correctly that the motor will restart with no problem perhaps 15 minutes after shutting it off, but won't an hour after shutting it off, but will again once the motor is fully cooled down? <<<
Not sure about the 15 min. Certainly difficult after an hour or so. No problem when fully cold.

[cbhinkel]

So, a question I have is do you use the choke when you're starting it after an hour cool down? If not, I would suggest to try that and get ready to quickly open the choke once the engine fires over so you don't flood the engine.

Also, feel free to try my carb cleaner procedure I posted about recently to see if that makes any difference. In your case, I wouldn't let the carb cleaner soak in for very long.....a quick in and out should do it. A deposit build up in the carbs could be indicated by a leaning out of the fuel/air mixture, possibly making it harder to start when the engine is only warm. OR, it could be many other things as well.

Good luck!
-Chris

[Harry van der Meer]

I have to use the choke at all times, if the motor has been off for more than 5 min or so. However, when it does not fire after 3 or 5 seconds, I shut off the choke for fear of flooding and crank again for 3-5 sec with the choke closed. If it still does not start, and it usually won't with the choke closed, I crank again with the choke opened. Eventually it will start, running rough for a bit (to burn off the extra gas) and then she will run nice.

It is just a nuisance if I need the engine in a hurry.

[Frank C]

It is just a nuisance if I need the engine in a hurry.

Excellent point, Harry. The more I read of carbureted motors, the more emphatic I am about encouraging motor shoppers to choose EFI.

Reminds me of the early days with my Corvette (two 4-bbls). Stumbling around turns, smell of gasoline when choking, bogging under acceleration ... all such automotive problems completely disappeared around 1980. While it can be even more critical for an outboard to start within 2 seconds, the Mfgs. continued from '80 until '98 before they began applying those lessons to marine motors.

Sorry for the frustration, and hope you find that gremlin soon!

[Moe]

You shouldn't have to use the choke when the motor is hot, or even warm. Sounds like it's running lean on the idle circuit (which is usually fed by the slow speed circuit). Those are the jets with the tiniest holes and more susceptible to leaning out from gumming up or clogging. That's where I'd be headed... and with the warning I haven't disassembled a Honda outboard carb, cleaning them and the idle mixture screw and seat. Screw the latter in GENTLY until it seats, counting the number of turns, so that when you reinstall it, you can seat it all the way GENTLY and then back it out to the previous setting. Others who've actually done this may have some tips or warnings for you.

[argonaut]

Eliminate the easy & cheap things first, tank vent, replace the bulb/line, make sure the choke works as advertised, cold and warm. Check the plugs for color to get an idea what's going on.
Failing that I'd give the chemical soak a try, seafoam comes in spray and liquid and is legendary. If you can get it in the bowls through the fuel lines and let it soak you might get good results, by all means try cbhinkel's technique. Yours at least still starts and runs so you can get cleaning chemicsl down in the carb where it needs to go.

Finally, all other non-invasive techniques having not worked, you may need a rebuild.
I rebuilt my carbs after chemical cleaning attempts failed and the local mechanics didn't want to touch them. The carbs are not very complex. The BF50A is notorious for jets clogging, and worse than that they are known to crack down on the orifice end of the jet. I had to use a jewelers loupe to examine mine when I took them apart, and found they were cracked though they still worked up to the point I managed to clog every orifice in all three carbs with green goo. If you decide to rebuild don't bother, just replace the jets. The jet orifices are tiny, as this carb was apparently designed for fuel economy and emissions rather than durability. They're Keihin brand carbs. They are not hard to rebuild but getting them off to do it is a pain in the arse and Honda didn't figure anybody would ever need a rebuild kit so you have to buy individual parts. Glad to help if you end up DIYing it.

Next time... get EFI, and buy whatever brand you -can- get parts and service for where you sail.

[Tony D-26X_SusieQ]

I used to have the same problem with an old 1977 Dodge van. Almost all of the time cleaning the carborator did the trick. In my case it was usually the choke that would get gummed and stick closed causing flooding. I used to crank the engine while I held the choke open till she cranked over then all was fine till the engine hit that temprature where the deposits would start to get gummy again. Good luck to ya!

[MAC26X]

My 2001 Honda exhibits some of the same tendency:
starts good cold with full choke
starts good warm with no choke
starts harder after an hour or so of sailing.

I've had good luck by using the neutral throttle advance to get the carb open beyond the idle jets. The engine control I have has a button right in the center of the control lever pivot that allows moving the lever forward without shifting into gear. I advance the throttle and try starting without choke. It generally starts right off but I have to quickly reduce throttle to keep the engine from "racing". If it doesn't start right off then I use the choke along with the throttle advance and get immediate results.

[Harry van der Meer]

I think I have found the issue. This past weekend the battery selector switch was set by accident to "both". I had it like this all weekend. Every time the motor started very quickly. Did not have to use the choke at all except first thing in the morning.

Last year spring, I moved both bateries. Originally, they were located in the settees aft and forward of the gally. I moved the first battery to the space in the port settee forward of the gally, as much forward as possible. The second battery was moved under the front berth, near the ballast tank vent.

I did not move the battery switch, which is mounted in the aft facing side of the port settee aft of the galley.

I used 2 AWG battery cable between the switch and the battery. From the switch to the motor the original 4 AWG cable was left in place.

I think I have too much of a voltage drop. The strange thing is that the motor turns over normally. Also it always starts quickly from a cold start. The problem was that a relatively warm start, after the motor has been off for an hour or so, has been problematic. This is what confuses me. The only thing I can think of is that because I use a batery charger when the boat is not in use, the batteries are fully charged at initial start.

Anyway, I will do some voltage measurements at the battery, switch and motor. Perhaps adding a second set of 2 AWG cables from switch to motor will cure this.

[Robert]

You make a good argument for a starting only battery near to the outboard motor. The discussion is in the Modifications list, I think the outboard will start much more reliably with a little battery with decent cranking amps right next to it. http://www.westcobattery.com/miata.html Mount this 5 inch wide battery at the transom behind the cover where the outboard startng cables are spliced to your longer 2 gauge cables.
..
With the cable modifications you may have extra splices, your problem with too much voltage drop might be in the connections. I'd start by varifying all the connections are very low resistance by making sure they are bolted with a lot of pressure and surface area in contact using corrosion resistant connectors or connectors sealed up very well.