Stiga powered mountfield wont start

[motorbiking]

I have a Stiga powered self propelled mower, its about a year old, my last mountfield had a Briggs and Stratton engine and lasted 20 years.

This one won't start, I suspect it's old fuel. It starts if I put fuel directly in via the spark plug hole and also if I poor fuel directly in the carb air intake and then runs for a second or 2. The fuel line is also clear and the carb "sump" leaks when you open the drain nut. So I am concluding this is a clogged carb?

What is the best way to clean the carb - carb cleaner spray?

There is a little nozzle that sticks up at the bottom of the air intake, is this the thing that is likely to be blocked?

 

[Burnerman]

Before you dive in......what sort of choke does the machine have - is it via a primer bulb or a lever on top of the carb?
A photo of the carb would really help if you can.
John

 

[motorbiking]

No primer bulb.

 

[Burnerman]

In which case there will be some sort of choke mechanism.
Often the carb has two flaps in it, operated by rods. One nearest the engine is the throttle, the other nearest the air cleaner is the choke.
John

 

[motorbiking]

The carb looks like this, I'd have to take the air box off for a photo, but I can do that.

Mountfield Carburettor for Stiga ST120 Engine - GLC Garden Machinery

Genuine Mountfield Carburettor / Carb for the Stiga ST120 engines produced from 2020 onwards. Fits many Mountfield / Stiga mowers with this 123cc engine.

jungle-busters.co.uk

I've poured fuel directly into if via the"Butterly flap" and it runs for a couple of seconds. There is no manual choke as far as I know.

 

[Burnerman]

The choke flap is the one on the right of the picture.
It may be automatically operated, but the flap must close completely to get a cold start.
Of course, there may be a blockage within - in which case its float bowl off (carb removed) using the central bolt, followed by the main jet and emulsion tube which the central bolt covers.
John

 

[motorbiking]

thanks the choke flap is closed when I try to start it, so I think its the emulsion tube that is blocked. I will take the float bulb off and clean it from there. This is what I was calling the carb fuel sump.

 

[Burnerman]

I don't know if this particular machine has a fuel tap or not, but when you remove the float bowl you'll see the plastic float inside.
Raising this with your finger shuts off the fuel flow, which will start again when the float drops.
John

 

[jj4091]

Is your mower the SP46 or SP51. To start with if it's less than 12 months old it should still be under warranty so it is the suppliers responibity to repair it. I've never had fuel go off in less than a year. It looks to me like either of those models has the choke that is operated cenrifugally by levers in the crank case. I can't see any throttle lever so is it controlled by the lever on the handle either fully open when pulled or fully closed when released.