Yamaha Malta problem.

ferrispeterchris

ferrispeterchris

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I am delighted with this small engine but a problem has arisen which I need help with. The engine starts first pull but after sitting at tick over for a while if you open the throttle it tries to die and you have to work hard to keep it alive. When it does "catch" it is slow to gain revs, when the revs do rise it will motor along happily. I am wondering if this could be due to too much oil in the fuel ( using 100:1) or a jetting problem. Unfortunately the engine is on the back of my little Hunter at the moment and it is blowing a hoolie so what would you suggest to fault find this prob when the wind dies? Many thanks.
 
Is this fault new or historic?

Does fully or partly pulling the choke out or hand choking over the inlet, if possible make it quicker to respond?

Though its usually the idling jet that suffers most, it could be muck in the main jet.
 
ferrispeterchris said:
I am delighted with this small engine but a problem has arisen which I need help with. The engine starts first pull but after sitting at tick over for a while if you open the throttle it tries to die and you have to work hard to keep it alive. When it does "catch" it is slow to gain revs, when the revs do rise it will motor along happily. I am wondering if this could be due to too much oil in the fuel ( using 100:1) or a jetting problem. Unfortunately the engine is on the back of my little Hunter at the moment and it is blowing a hoolie so what would you suggest to fault find this prob when the wind dies? Many thanks.
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Firstly do not ever feel tempted to run on a less oily mix than 100:1 (1%). It really is the minimium . Personally I would run it on 50:1 (2%)ifpossible, if not then 75:1. I assume you are using the correct grade of 2 stroke outboard engine oil (TCW3)

Two things i would try

A new correctly gapped spark plug.

A full carb clean, esp if choking it as suggested helps, checking also the float height adjustment.
 
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A blocked carburettor is very common with these small engines.
Your symptoms fit in (sort of).

The most common story is to start OK, but die as soon as you open the throttle.

Cleaning the carb would be my first step. I have done this so often on my, and friends small 2 stroke outboards that I can now do it without dropping anything in the water :)
 
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Before you take it to bits to clean the carb, make sure it is not just the fuel-strainer at the bottom of the tank that is clogged. Easiest way to clean it is just shake the engine, empty the fuel out, and add fresh fuel.
 
I think that would be more obvious at higher revs. At tickover it's unlikely the fuel level in the float chamber would be too low.

I would start with a new plug.
 
You don't say what happens if you open the throttle straight away when starting, only after leaving on tickover for a while. Blocked intermediate jet could be the problem but it could also be the coil breaking down with high demand when throttle opened.
 
One other thing I forgot to mention. I swung the engine round to give "reverse gear" and forgot to put the "latch" on and it kicked up a bit. There was fuel dripping out of the casing for a while after that until I stopped the engine. I am guessing this was a sticky float?
 
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