I have copied this posting over from another topic. I wrote it in April. My reason for writing it, is that I think that more than one engine in the 4 - 6 hp range, with an internal tank may have this problem. A friend's 6hp Suzuki most probably had the same problem. We never got the idea to try it with theexternal tank instead...

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Since safe starting of any aux. engine is a part of this thread, here is an experience that I made only a week ago.

A friend down the street called me and asked for help because his outboard engine refused to start. On arrival, I found he had mounted it on a 3-legged stand with the leg in a drum of water. The motor was a quite new 6hp, 4-stroke Tohatsu, almost identical to mine (on Ingeborg), except that this had an inboard tank in addition to a connection to an external one.

We opened the petrol valve and pulled the cord, but no sign of life. Off with the hood and out with the sparkplug. The sparkplug looked fine and produced a nice spark when testing it. Funny that, I thought after we had refitted it: That sparkplug should have been wet after all our pulling with the choke on. Then I had a look at the tank.  It was a flat, tall thing; right in front of the engine. It was about ¼ full, and then I noticed that the ‘waterline’ of the fuel was well below the carburettor. In other words, if the carburettor was dry when it was to be started, an awful lot of pulls would be needed until the internal pump had filled it up to let it start. We then just filled the tank right up and waited for twenty seconds before pulling the start-cord again. Then the engine started right away, and ran sweetly.

Moral:
If you have one of these 4-6hp outboards and mainly want to use the internal tank, check the position of it with respect to the carburettor. If it is like my friend’s Tohatsu, then keep it topped up to ensure a quick and easy cold start when you suddenly need it.

Arne

David Webb wrote:

Hi, with reference to the varnish/gloop build up in carburetors, I always shut off the fuel and run the engine dry if not using it for more than a day or so. Using this method I have never had any varnish/gloop build up and the engine always starts easily after being laid up for a while. I also recommend this  for four stroke engines as evaporating fuel, even without two stroke oil in it, can still leave a varnish build up.

I think is also worthwhile to remember that when talking about outboards we are discussing a huge range of motors.  An old Seagull I had exuded oil out of virtually every orifice and was in fact designed to work well while doing so.  The last outboard I owned, a modern Tohatsu, was rated something like EPA Tier IV and I could sniff around the carburetor and barely smell gas.  I suspect newer motors are far less prone to the problems many of us have suffered with gunk and varnish on older motors.  At the same time I think they are more susceptible to fuel contamination problems.

Most outboards come with tiny fuel filters of questionable ability.  If you are using one as your primary propulsion, putting a Racor into the fuel line isn't a bad idea.  I've also had good results with a Flotool or Mr. Funnel filter.  Despite the cheesy advertising, it does occasionally pull stuff out of what I would have thought to be a good quality fuel source.

Arne Kverneland wrote:

The vinegar method, details please!

Bryan,

you mention the use of flushing the cooling system with vinegar to dissolve salt deposit. Could you elaborate a bit on how you did that?

Did you just pour vinegar in a half drum of freshwater as the engine was running in it, or did you actually flush pure vinegar into the water-inlet (with a running/stopped engine)? In that case, did you just let the vinegar sit in the water channels over-night? I have not heard about this method before.

On my 7.5hp Honda (bought in 1985 for Malena) there was a cooling water blockage every other year. The first few times I solved it by opening a lid in the engine block to get access to the problem spot. Later I learned that one could clear the cooling system with pressure air. When Malena was sold, the new owner appear to have ignored the lack of cooling water, so the engine over-heated, the block warped and blew the top gasket (around 1999). End of story. Too bad  -  that engine had been really good, and produced a wonderfully nice sound (think of the 125ccm Honda Benly motorcycle).

Arne

 

Yes, as you said, I just used a healthy amount in a large bucket, dangled the lower end of the outboard into the bucket, and ran the engine until it came up to temperature. It would certainly be better to use pure vinegar, and let it work overnight, but a key part of the process is that the engine must be hot. I'd flush with fresh water afterwards, using a motor muff (the sprung cups that couple a hose to the water intake on the motor that makes your outboard look like a big-city hospital doctor). 

The deposits that give us grief are not salt, which being water soluble wouldn't cause any heartaches. It's the hard scaling of what I guess are carbonates (?) which do the damage. Vinegar is simply a cheap, readily available weak acid. Phosphoric acid would be more effective. A range of commercially available non-marine descalers can be found, but many react with aluminium and can't be used. Vinegar is the poor man's alternative to the products on the shelves of your local chandler.

Bought a new Honda 10 hp outboard 2006 with elecric start and remote control/steering replacinga 2 stroke 8 hp Johnson. Engine was all the time on the transom and the boat in the water. Serviced it for the first time now after 10 years, because I thought maybe its about time to shift the oils, impeller and spark plugs, although it still ran... oil and impeller still looked almost new, the spark plugs were quite black and seemed to be the reason that it didnt start immediately this spring. However, it was quite an effort to loosen the screws and bolts. But otherwise they seem to take mistreatment quite well. Astonishingly, I use the same cheapo starter battery and only needed to charge it this spring for the first time because it was dead after the winter. The batteries for the boat electricity, which are seperate, had to be replaced twice during those same years. I have installed a remote steering where the wheel can be attached when leaving from the box in the harbor otherwise it is stowed away. Without it northerly winds turn the boat so that i have to reverse all the way out of the marina. With the steering I can easily adjust the direction of the thrust and there is no danger that I scratch someones excessively more expensive floating pride.

On the negative side, the smiling 28 looks stupid with an outboard and due to its hull shape encourages the prop to surface when motoring through short waves. The excessive weight of the motor needs to be balanced by 100 liters of water in the bow tank. I also plan to replace the monster with an electric outboard. Would I buy a gas engine today, I probably would go for a 4 or 6 hp engine with some selfmade remote steering. The current engine being so heavy that I chose to do the service from the dingy instead of taking it home. The previous owner had replaced the inboard gas engine and saildrive with a 2 stroke which actually could drive the boat a little bit faster than the much heavier Honda, but it stank. I also through out the inboard tank because it was much too big for my purposes and not even empty after 2seasons but with all kinds of things (bits of silicone) floating in there clogging the lines as found out in a less appropriate moment. With the current 12 litre tank I almost empty it in a season and can inspect its contents even when it is not empty. And if necessary easily flush it/filter the remaining fuel. 

David Tyler wrote:

I've never been a petrol-head, but now I'm going to have to learn fast. I take it the vinegar goes into the tank of cooling water and not into the petrol. Is cheap malt vinegar good enough, or will my engine prefer organic apple cider vinegar for its health-promoting properties?