Very small fuel leak on lawnmower - where to look?

[Condi]

I'm finding that the mower is losing fuel while it's sat in the shed. Looked like the fuel tank had a crack so replaced that, but it's not solved the issue so need to look further. There are no obvious signs of fuel on the mower, so I can only assume it's evaporating rather than dripping out. Can anyone suggest any places to start, or is it just a case of taking the fuel lines and carb off, replacing any O-rings and checking for damage?

[netherfield]

You haven't mentioned a make.

I had an Honda engine on a machine, under the tank where the fuels comes out was leaking, unscrewed it new O ring, sorted, and that was the tiniest leak.

[grumbas]

I had this on an old mower, the o-ring on the filler cap was very perished.

Don't forget E10 fuel likes to eat hoses etc if they're not spec'd for it.

[shtu]

They're simple machines, there's really only a few places to look.

Tank
Pipe
Carb

[3din]

replace all fuel pipes. e10 eats through them unless they're specifically rated for it.

[Alex_225]

I have a Webb petrol mower. I started to notice fuel down the side appearing more and more, initially I assumed I'd just been clumsy filling it up.

I realised the fuel line had split and was peeing fuel out, £5 part and a 10 min job to replace.

[jimothyc]

This is why I only use super unleaded in my mower. Supposed to be up to 5% ethanol, but normally has little or no ethanol compared to the standard E10.

[Condi]

netherfield said:

You haven't mentioned a make.

It's a Briggs and Stratton engine.

Guess I'll just start taking things apart and see what I can find.

[RicksAlfas]

It was the fuel pipe on mine. Looked ok but when you moved it you could see it was very worn and breaking up.
Loads on ebay or Amazon.

[OutInTheShed]

Condi said:

I'm finding that the mower is losing fuel while it's sat in the shed. Looked like the fuel tank had a crack so replaced that, but it's not solved the issue so need to look further. There are no obvious signs of fuel on the mower, so I can only assume it's evaporating rather than dripping out. Can anyone suggest any places to start, or is it just a case of taking the fuel lines and carb off, replacing any O-rings and checking for damage?

Could just be evaporating from tank and carb in the hot weather we've had?

Is there a fuel tap?

[Peanut Gallery]

Is the oil level increasing? - carb float is not sealing fully, overfilling, flowing through to combustion chamber, leaking down into sump?

[bobski1]

What spec fuel hose do you change to? Assuming you can buy it in lengths. I have an old honda and the fuel pipes will need changing soon, the ends are just twisted wire rather than jubilees, do they have a proper name?

[allegro]

no suggestions as to a fix but I can confirm that lemonade makes for a very effective fire extinguisher

[RicksAlfas]

bobski1 said:

What spec fuel hose do you change to? Assuming you can buy it in lengths. I have an old honda and the fuel pipes will need changing soon, the ends are just twisted wire rather than jubilees, do they have a proper name?

Take the old one off and measure it. They tend to use clips for the ends.

e.g. https://www.ebay.co.uk/itm/256248061694