help needed for outboard novice

[SteveJohns]

I have an inflatable and have just acquired a ten-year-old Suzuki DT.3.5 two-stroke outboard. I know very little about outboards but am aware of a couple of problems with the motor.

1: the engine does start but the propellor does not turn, regardless of whether it is in 'neutral' or 'drive'. Is the shaft broken? or may it simply be disconnected from the prop? May there be an easy fix?
2: when the engine is running it seems to race/surge; it is very difficult to maintain at a constant RPM, and also will not idle without cutting out completely.

Any help, no matter how patronising it may sound, would be appreciated. Thanks.

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[bruce]

if you just purchased the motor, take it to a pro for checkup before the rnli have to tow you in because it failed. your comments about the motor indicate the need for a 'tune up'

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[floatything]

I don't know this particular outboard, but the prop not turning may well be due to a broken shear pin. This is a short softish metal pin that fits in a groove in the back of the prop, and also passes through a hole in the final drive shaft. Its purpose is to break (shear) if the prop hits something or gets badly fould and helps to protect the prop and engine. Take the prop off and have a look.

The lumpy running could be due to a number of things. I would:

Remove, check and replace the spark plugs if needed.

Clean out the carburretor and blow through the jet (s)

Drain the fuel and replace with fresh. Its probably worthwhile replacing the in-line fuel filter as they are cheap and so not really worth trying to flush through.

If none of this helps then (if you know how) adjust the carburretor settings.

Hope that helps



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[JimMcMillan]

Floatything has it right only might add to check no fuel pipes are bent or kinked and dont forget the jet under the float.

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[SteveJohns]

If the problem is the shear pin, as you suggested, how can this be rectified? I see the pin, which is like a nail, in the the middle of the prop but it is securely in place.

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[Jools_of_Top_Cat]

What you are seeing if you have not removed the prop is where the split pin is supposed to be. The sheer pin will be behind the prop.

As a test, can you spin the propeller freely, with the engine stopped of course.

Remove the bent over (hash job) nail, remove prop and check for a small pin through the shaft, this will look like a 2cm metal dowel, it may have score marks on it to aid breaking. It is very normal to break these pins as you come into shore, a lump of seaweed, plastic bag, rock etc.

You should when buying a new one buy two spares, they should only be a pound or so to buy. Oh, remove bent nail and buy some stainless split pins, one to fit and two spare.

As to the surging, I agree with above, strip and clean carb and bowl including needle valve. Change fuel, would not consider filter at this point, but you might as well if one is fitted. Also change the spark plug.

An important point though, have you unscrewed the air trap on top of the fuel filler cap, if you don't the engine will not be able to suck fuel due to the vacuum being formed in the tank. Air needs to enter the tank as fuel leaves.

hope this helps....

<hr width=100% size=1>Julian

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[Guest]

I would think that once prop shear pin is sorted - some of the probs would disapear ...

but the bad running ....... sounds like gummed up jets or similar. Has it stood with 2T fuel in it for long time ? The tank vent would allow the light ends of petrol to evporate and in so doing allow the fuel to thicken up and possibly gum if left real long time. Petrol is ok left stored, but when mixed with 2T it needs to be really shaken up before use. If in engine tank fixed to engine frame - not so easy.


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
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[William_H]

Assuming your outboard is something like a Johnson you remove the bet nail or split pin through a nut on the end of the shaft. The nut can then be unscrewed. This should allow you to pull the propeller off.
The shear pin is inside and if broken will come out as 2 small pieces about 1cm long with another section still in the shaft in a hole through the shaft. This will have to be pushed poked or bashed out using a punch or nail. You will see then how a new shear pin will fit through the shaft extending out each side to engage with the propeller when refitted. you certainly need to know how to replace this pin on the water. a classic way of breaking the pin is if the moter is difficult to start and finally roars into life. If you put it into gear at engine revs too fast the enertia shock will shear the pin it is easily done. I will get shot for saying this but in emergency you can use piece of suitable sized nail or it is even possible to remove the centre broken piece and fit the 2 end broken pieces into the shaft to provide enough length to drive the prop to get home. you need to get into it yourself to find out about these things. regards will

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