Lawnmower : do I need new carborator?

enfant terrible

Hi guys,

Had an issue with my lawnmower not starting, after checking the spark plug I check fuel line and noticed there was no fuel moving from the petrol tank to the carborator.

After draining the petrol tank a black sludge came out of the bottom of the tank. I'm assuming this blocked the fuel line.

I ordered new fuel line, filter, spark plug and fuel and installed them yesterday. Fuel was now flowing from tank to carborator. Engine still didn't start at all so I got some carborator spray, took carborator out and took it apart and cleaned it. Followed a guide on YouTube to clean it. It was actually pretty clean already.

Primed engine and tried to start again and this time it started on first pull but conked out after a few seconds.
Tried few more times and same think conks out after few seconds.

I loosened the nut on the bottom of the carborator and fuel dribbled out so fuel seems to be getting to the carborator.

Is it possible the sludge made its way to carborator and I need a new one despite it looking clean?
Anything else that could stop engine running?

It's a mountfield rs100 lawnmower.

_Brian

Carb needs strip down, clean and rebuild.

It’s a fiddly job but not that hard. And will take abkut 30 minutes.

If your not competent to do this drop the mower off and ask for a carb clean and service. It won’t be expensive €45-50 if there are no major parts to replace.

enfant terrible

_Brian wrote: »

Carb needs strip down, clean and rebuild.

It’s a fiddly job but not that hard. And will take abkut 30 minutes.

If your not competent to do this drop the mower off and ask for a carb clean and service. It won’t be expensive €45-50 if there are no major parts to replace.

Ya I already took the Carb apart and cleaned it with Carb spray, cleaned all the valves and it came back to life but dies after a few seconds.

Followed this guide, at 40 mins in he cleans carb
https://youtu.be/Izaiao1ltVw

Could the sludge have gotten into the Carb and done irreversible damage to it?

_Brian

Carbs are fiddly things. Many ports for a tiny amount of stuff to get stuck in.

It’s possible there is damage but majority of the time a clean is sufficient. Sometimes new gaskets.

If I have time I’ll give cleaning a go but it’s not always successful and I’ll drop it to repair centre.

We run a bunch of mowers, strimmers etc and replacing a carb is rare. The fact that it’s starting I’d still think fuel.

enfant terrible

_Brian wrote: »

Carbs are fiddly things. Many ports for a tiny amount of stuff to get stuck in.

It’s possible there is damage but majority of the time a clean is sufficient. Sometimes new gaskets.

If I have time I’ll give cleaning a go but it’s not always successful and I’ll drop it to repair centre.

We run a bunch of mowers, strimmers etc and replacing a carb is rare. The fact that it’s starting I’d still think fuel.

Ya the original problem was sludge at bottom of petrol tank. I didn't clean the tank physically just drained and put fresh petrol in. Maybe the feed from the tank is blocked slightly.

Maybe I should drain tank again and try clean it somehow.

Can I fire carb cleaner into the fuel tank outlet?

_Brian

I’ve never done that so I don’t know.

Any time a tank gets contaminated we have it removed and washed out.

enfant terrible

_Brian wrote: »

I’ve never done that so I don’t know.

Any time a tank gets contaminated we have it removed and washed out.

Do you just was it with a hose and let it dry out?

enfant terrible

Just to update I ordered a new carburetor from ebay and fitted it today and lawn mower started on first pull.

Thanks Brian for the advice.

_Brian

enfant terrible wrote: »

Do you just was it with a hose and let it dry out?

No rinse with petrol not water.

_Brian

enfant terrible wrote: »

Just to update I ordered a new carburetor from ebay and fitted it today and lawn mower started on first pull.

Thanks Brian for the advice.

Good result.

fryup

OP to save yourself any future hassle use a funnel with a built in filter when filling up with petrol, prevents any muck getting into carb

legend99

Petrol also "goes off" - about 30 days from what I have read online. Some people say that if you're going to be leaving the tool in the shed for than a month then you should run the device dry so there is no petrol left in it that can make the type of sludge you describe. It's also said that if you try to use petrol that you have had in a jerry can for a few months then it's far more difficult to start your engine - lawnmower etc. - again because it's gone off.