Honda BF8D blocked jet nozzle

[TonyMS]

For the coast 10 years, we used a Honda BF8D outboard as the main engine on our lightweight catamaran. For 8 years it was totally reliable. Then, 2 years ago, it just stopped working. The cause turned out to be that the jet nozzle in the carburettor, which is a very long thin tube, was gunged up. Since then, I've been punctilious about using fresh fuel, and have installed a bulkhead-mounted fuel filter. But, several times a season, it gets blocked up again, and I have to dismantle the carburettor and clean the nozzle (using acetone and soft copper wire).

Presumably the problem is modern bio petrol combined with the design of the carburettor. The Tohatsu 2-stroke I use for the dinghy happily drinks last year's untreated petrol.

Are there any additives I could use that would prevent this problem? Are any makes of petrol better behaved? Would super work better than unleaded 95? Or can anyone suggest anything else?

TonyMS
Razzmatazz

 

[dewinowens]

I have the same engine and have been fortunate to avoid problems so far (touch wood). I have a bulkhead-mounted primary fuel filter / water separator and as the engine only gets fairly occasional use I either run the carburettor dry after using it, by disconnecting the fuel line and waiting for the engine to stop, or by draining the carburettor using the drain screw. The drain screw probably drains the system more completely and the fuel drains out from the nozzle next to the cooling water tell-tale. Apparently the jets get blocked by the unused fuel leaving sticky residue when it evaporates from an unused engine, so I hope that draining the fuel will reduce the chance of this happening. As an aside, I did have problems with a Honda lawn tractor that seemed to be caused by blocked jets and a tank full of super unleaded sorted that out, so that’s definitely worth trying.

 

[RichardS]

As Dewinowens says, draining the carb using the carb drain if the motor is going to be unused for more than a few weeks is probably the only guaranteed solution.

You can get additives which have been mentioned on here before but whether they are an infallible solution, I know not as I've never tried them.

Richard

 

[VicS]

Sta-Bil fuel stabiliser seems to be very popular with outboard users in the US.

http://sta-bil.co.uk/shop/

Briggs and Stratton Fuel Fit Stabiliser appears top of some UK reviews and may be more readily available in the UK

https://www.briggsandstratton.com/eu/en_gb/products/care-products/fuel-fit.html

One of these may well be worth a try, or indeed Honda's own fuel stabiliser

https://seamarknunn.com/acatalog/h2...MIyLTDnKuC2wIVTDobCh29eQ75EAQYASABEgIZtPD_BwE

 

[steve66]

Sta-Bil fuel stabiliser seems to be very popular with outboard users in the US.

http://sta-bil.co.uk/shop/

Briggs and Stratton Fuel Fit Stabiliser appears top of some UK reviews and may be more readily available in the UK

https://www.briggsandstratton.com/eu/en_gb/products/care-products/fuel-fit.html

One of these may well be worth a try, or indeed Honda's own fuel stabiliser

https://seamarknunn.com/acatalog/h2...MIyLTDnKuC2wIVTDobCh29eQ75EAQYASABEgIZtPD_BwE

If you drain the fuel before periods of storage you won't have any more issues

 

[TonyMS]

Thanks for all the input. I'll work my way through them until I find something that works! However, I already drain before leaving for more than a few days, and still have the problem.

TonyMS

 

[Boathook]

As Dewinowens says, draining the carb using the carb drain if the motor is going to be unused for more than a few weeks is probably the only guaranteed solution.

You can get additives which have been mentioned on here before but whether they are an infallible solution, I know not as I've never tried them.

Richard

If I'm not going to use my main engine (Honda 30) for more than a week I disconnect the fuel line at the engine and let it run until the carbs are drained. I have never had a problem with gunge in the carb, though dirty fuel is another matter after it got through 3 filters !