Honda BF6b Starting Problem

[tjbrace]

I have one of the above outboard motors which has an intermittent starting problem. It has been to various experts when it fails but always runs perfectly for them. One dealership took the motor in last week to try to cure the fault, I demonstrated the non start at their workshop but they weren't able to check it for 4 days by which time it was working perfectly.

Part of the electronics is black box with several wires emerging and is called a CDI (capacitor discharge ignition). Apparently there is no test equipment available for this unit and the replacement cost is £240! Does anyone know how I might drive this unit to see if its doing its job when the engine is in the failed state. Thanks

 

[VicS]

I take it that if you can start it it will run Ok and not stop again of its own accord.

I think the first thing would be to check for a good strong spark. If there is a spark then you have to look at the fuel system and carb for a possible cause.

If you have no spark then I think the most obvious thing to check is the stop button (and associated wiring.) I'd be looking for the possibility that the stop button has stuck/is shorting from the time you previously stopped it

Not very helpful sorry.

 

[Lakesailor]

Try this lot http://www.mareng.co.uk/index.php.
They don't list CDi stuff for the Honda, but do other makes.
I rang them and they were very helpful. They may be able to test your unit.

 

[John the kiwi]

honda wont start

I have an older honda 15hp with identical problem that i have been wrestling with for 2 years.
Sometimes will start and run immediately and other times not. When it doesn't, start all i have to do is wriggle the plugs/wires where they go into the CDI and voila. Once running it never falters or stops.
So i had the motor running in a drum and in turn carefully wiggled each wire where they enter the CDI plug with needle nosed pliers, and could induce it to miss and stop altogether (though this doesn't happen in normal running.)

Confident therefore the fault had to be the a broken wire or bad plug, I bought complete new wiring harness confidently expecting to fix the problem.
It didn't.!! I have concluded therefore that the CDI has a dodgy connection internally to one of the pins.
When i first attempt to start, i can tell whether it is going to start or not. If connection is good, it goes first or second pull. If it feels dead on pulling the first time, then it doesn't matter how many times you pull it, it wont start, but now I know to lift the cover and give a quick gentle wiggle to the wires at the cdi and pull again. This always, always works and the motor will at least fire on the next pull and usually start.

I have spoken to the chief mechanic at a large Honda OB dealership in Australia and they have never heard of this problem.

I can buy a CDI from the site listed below for half price the local Honda agents want but i have recently read that the CDI units used by Honda on OB s are exactly same as used on Motorbikes.
My plan is to visit the Motorcycle Dismantlers next time i am in the big smoke and see if i can get a second hand one that is the same externally and try it. (Honda are quite shy about supplying part numbers that you can compare for these units.)

(This is where i got the harness from.)
http://www.boats.net/parts/search/Honda/Outboard Engine/parts.html

Good luck

 

[CharlesSwallow]

I once had a BF75 as the engine on a 23ft sailing boat. It was very reliable, once started and that engine motored us across from Poole to St Malo, through the Brittany canals, into and around the Gulf of Morbihan and all the way back to Poole again without missing a single beat. However, initially it was a ba5tard to start. My favourite technique, eventually learned, was to give it one pull with the choke out - at which it would just cough then return the choke and give it a second pull when it would roar into life. I discovered that the reason for this was that the dissimilar metals of the carb. body and the slow speed jet tube produced a sludge of aluminium oxide in the bottom of the jet tube which blocked it's fuel supply. Cleaning this regularly and using RedEx in the fuel cured the problem completely. I never had any trouble with the CDI ignition in seven years although the pressed steel flywheel on that model corroded badly but I cured that by replacing it with a cast iron one from a scrap VP 7.5hp Saildrive which used the same powerhead.

Chas

 

[VicS]

I once had a BF75 as the engine on a 23ft sailing boat. It was very reliable, once started and that engine motored us across from Poole to St Malo, through the Brittany canals, into and around the Gulf of Morbihan and all the way back to Poole again without missing a single beat. However, initially it was a ba5tard to start. My favourite technique, eventually learned, was to give it one pull with the choke out - at which it would just cough then return the choke and give it a second pull when it would roar into life. I discovered that the reason for this was that the dissimilar metals of the carb. body and the slow speed jet tube produced a sludge of aluminium oxide in the bottom of the jet tube which blocked it's fuel supply. Cleaning this regularly and using RedEx in the fuel cured the problem completely. I never had any trouble with the CDI ignition in seven years although the pressed steel flywheel on that model corroded badly but I cured that by replacing it with a cast iron one from a scrap VP 7.5hp Saildrive which used the same powerhead.

Chas

Which is why in my earlier post I said the first thing to do was the check the spark. If there is a good spark then a problm like yours may be the cause of the OP's non starting.

If there is no spark then that has to be sorted before going any further.

 

[tjbrace]

Many thanks for the replies. I will contact the electronics company linked by Lake Sailor tomorrow hopefully.
When the engine is in its failed state I cannot see a spark with the plugs exposed, and if it starts it runs very well. These observations convince me that an electrical fault rather than fuel supply/carburation is the cause.