If you have trouble with a small outboard motor it can often be attributed to the fuel. David Parker describes how he saved a lot of money with a careful strip-down and clean of the carburettor
Even F1 teams are suffering from E10 fuel woes. This weekend past at the start of the Grand Prix season, it would appear that the start of the campaign by the new world champion is marred by what appears to be issues caused by E10 petrol.
A good enough reason to revisit this article on how to clean the carburettor on a small 4 stroke outboard which seem to be particularly vulnerable if left for a time with E10 fuel in them.
It only took me a few trips of rowing my trusty tender up the busy River Hamble to my main boat to make me realise how much I missed the convenience and ease of my little outboard engine. Unfortunately it had developed a gearbox problem that was not going to be straightforward to fix.
A friend kindly loaned me a Honda 2hp to tide me over, but I never feel comfortable borrowing other people’s equipment. I always worry something might happen to it, so I decided I needed to sort myself out with a replacement engine pretty quickly.
However, it turned out to be a bit of a case of ‘buy in haste, repent at leisure’. I saw an advert for a Suzuki DF2.5 on the Isle of Wight, the same lightweight engine as I’d had before. So I made a bit of a rushed trip over in our Seaward 23 to see it. Now, although it is only a short crossing, Solent waters can get pretty frisky (as many readers will know), and this was one of those days.
In fact, things got so lively that water from waves breaking over the boat was forcing itself through the wheelhouse windows, and the thumping we got even left a cabin light hanging down by its wires below. The signalling horn also got such a drenching it would not work again afterwards and needed to be replaced.
There were very few boats out, and on the radio we even heard a Mayday being called in, so by the time my son and I got to see the engine I was keen to buy it and get back again. I should have been more cautious, because the engine would not idle properly and the seller seemed to have to rev it excessively to keep it from cutting out.
However, the engine was only four years old, and although the tank had been topped up with new fuel we agreed that it must have been old fuel in the carburettor causing the problem. I should have investigated the problem more thoroughly, but I handed over the cash and we set off again.
Problems persisted with the engine when we got it back. It still wouldn’t idle and had to be revved excessively to keep it going. This meant you had to be very careful how you throttled back enough to engage drive so you did not damage the gearbox.
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Also, when I laid it tiller side down and petrol leaked all over the boot of the car, I kicked myself again for not checking the motor more thoroughly. It was then that I took a look inside the fuel tank for the first time. The fuel had serious deposits of dirt in it, and the tank would need to be completely cleaned out.
Then something else caught my eye lying in the bottom of the engine compartment: it was a gasket from the carburettor, so no wonder this engine had leaked fuel all over the place. Clearly the carburettor had been removed at some point, so not only had it been incorrectly refitted, the reason for the strip-down indicated this engine had had more problems than I’d been aware of.
Changing the fuel and refitting the gasket helped the running and starting of the engine, but it still refused to idle. Phone calls and visits to various dealers unfortunately didn’t shed a lot of light on the problem, and one said I would probably need a new carburettor. Another said the carburettor could be ultrasonically cleaned, but if that didn’t work I would then need a new carb – so potentially a bill with labour of over £160.
I took the engine away and did quite a bit of research online and on forums such as PBO Reader to reader forum, gathering information bit by bit. Many small outboard carburettors share features in common, and one of the most useful things I found was also being able to download a parts diagram for this one which was not included in the basic service manual.
Anyway, after a lot of trial and error I was able to cure the problem myself. Here’s what I did.
Removing the Carb
To investigate the problem further, the carb needed to be removed
Cleaning the Carb
As published in PBO March 2017