Tohatsu 3.3hp 2 stroke carburetter

E

eddystone

Well-Known Member
Joined
18 Aug 2013
Messages
1,936
Location
North West Devon
Visit site
Does anyone know where I can find a diagram of the above online; the "Owners Manual" on the Tohatsu website doesn't go into that sort of detail. I've got the covers off and the carb looks easily accessible but all I can work out is the idle screw and the screws to detach the float chamber. All I want to do is clean the float chamber and the jets. Also the throttle lever leads to a plunger on top of the carb - when the throttle is closed the plunger doesn't drop back all the way without a finger push.
 
You can strip the carb without reference to a manual, there aren't really many parts to it. Take the float bowl off and this will give you access to running jets and needle valve (once you've removed the float itself). Use good quality carb cleaner (no sniffing!) and ensure you clean the inside of the body. You may well find that the throttle slide is 'holding up' due to petrol varnish. Modern fuel has too much Ethylene in it, and this quickly goes off and gums-up.
 
Dead easy. The bowl is held on by 2 screws. You need a skinny longshaft screwdriver to get to one of them. Remove the main jet and blow it out.

Blow out the idle jet passages.

Check that fuel is flowing freely through the float needle by opening the fuel tap for a couple of seconds.

Reassemble and test. There is a good chance that you will have to do it again soon if the engine was stored with fuel in the tank line and carb.

I have never bothered with carb cleaner.
 
The two problems I have had with my Tohatsu 3.5 is the small needle lifted by the float to shut off the fuel and control the fuel level get clogged by gummy deposits, as others have said. I have also had the needle point (which is a tiny rubber insert to form a point) rot away and require a new one.
 
eddystone said:
Is it OK to clean out jets with paraffin?
Click to expand...

The carb cleaner will be thinner and will penetrate better as it is expelled under gas. Paraffin's fine for old fashioned SU and Stromberg but I'd probably not use it in WEBER. Similarly old bike carbs are fine but I"d not use it in a Modern Khelin.

"Unleaded" fuel and my Garden Machinery carbs don't mix well and with the exception of my Honda Lawnmower the carbs are tiny investment castings and I don't like to poke through the jets with thin copper wire.
 
Last edited:
eddystone said:
Is it OK to clean out jets with paraffin?
Click to expand...

Its OK but probably not as effective as some carb cleaner

You may also find it necessary, if you dont have a compressed air supply, to poke a thin wire through the jets.

If you use a copper wire, eg fuse wire, there is no risk of damaging the jets

You should be able to find an exploded diagram of the carb on the boats.net website http://www.boats.net/parts/search/Tohatsu/Outboard/parts.html
Although no substitute for a manual it will be very useful in the absence of a manual
 
I think you mean a Tohatsu 3.5 - the 3.3hp are the rebadged Mercury or Mariner versions.
I frequently cleaned the carb on my £M80, Mariner, never with any long-term success. I did find, if the carb needed cleaning so did the whole fuel line including the tank.
I finally bought a new carburettor, cost €42, fitted it 18 months ago and have had immediate start and running since then, with no fuel-flow problems.
The dinghy is used for getting ashore when anchored, a frequent trip during the 6 months I'm on the boat - so far, in 18 months, used about 20 litres of mixture, about 40hrs running. Distances run from 300 yards to 1.3nm.
Once the carb wears, problems appear to be unending, most appearing as fuel-flow obstructions.
I wouldn't change the 2-stroke for a 4-stroke - the better power/weight ratio and greater simplicity are winning combinations - apart from the cost advantage!!!
New 2-strokes available from Mainbrayce in Braye and a couple of Marseilles' chandlers, and from all the N African Arab states- those who consider themselves outside the EC regs.

PS My first 3.5 Tohatsu, outlived 3 dinghies and was stolen (though chained) in Siracusa; just as EC ordinances banning the sale of 2 stroke OBs came into force!!!
 
Last edited:
Flica said:
snipped ....
I finally bought a new carburettor, cost €42, fitted it 18 months ago and have had immediate start and running since then, with no fuel-flow problems.
Click to expand...
Where did you buy a new carb?

I have two of these engines, and have the same views as you: don't want a heavy four-stroke. I asked my local dealer for the price of a spare complete carb and he suggested it would be almost cheaper to buy a new outboard. Every year I have to dismantle and clean carbs and fuel lines/filter. Nothing else ever goes wrong.
 
jwilson said:
Where did you buy a new carb?

I have two of these engines, and have the same views as you: don't want a heavy four-stroke. I asked my local dealer for the price of a spare complete carb and he suggested it would be almost cheaper to buy a new outboard. Every year I have to dismantle and clean carbs and fuel lines/filter. Nothing else ever goes wrong.
Click to expand...

It came from the Greek Tohatsu distributor - prices in the UK are otherworldly.
You could try:
Fairweather Marine Ltd (Retail & Service) Fareham PO16 0XH 01329 283500 info@fairweathermarine.co.uk

I've found them helpful if not cheap, but entirely honest (unlike your supplier).
 
You must log in or register to reply here.

Share this page

Top