Petrol lawnmower question

[Clariman]

Last year I bought my first ever petrol lawnmower, so I am still a novice. Today I struck something with the rotary blade so switched it off and gently tilted it sideways to check. I was careful to tip it away from the petrol cap. However, at the end of my mowing session I noticed petrol or oil dripping from under the bit that has the choke button (or whatever you call it on a lawnmower).

The oil and petrol caps were on securely. Do they have overflow or aeration gaps where it might have leaked from or might I have damaged the lawnmower in some way? How can I tell?

The lawnmower model is this one and has a Briggs & Stratton engine https://www.coreservice.co.uk/wp-conten ... 191108.pdf

Thanks

[csearle]

I imagine the fuel is leaking from the place the air and fuel is combined, maybe from the place the air normally enters, or maybe an overflow. I think I'd only worry about it if it persisted. C.

PS The fuel tank will probably have a small hole to let air replace the petrol as it is used.

[richlist]

I've got a mower with a Briggs and Stratton engine. A couple of years back I did similar to you. The result was that oil from the sump ended up in to the air filter which needed replacing. Suggest you check the air filter and the oil level before proceeding.

[bungeejumper]

Been there with my last Briggs & Stratton, got the T shirt. You've probably just slopped a bit of engine oil during the tilt-over - it can happen, as others have said. Personally, I didn't get oil into my air filter - although it's probably of an oil-soaked-sponge type anyway!

In which case, wring the filter reasonably dry (it's usually a single screw that has to be undone), check the sump oil level, and if you're happy, fire it up. It'll probably smoke a bit at first, but that'll quickly dissipate. Tough old birds, Briggses.

BJ

[bungeejumper]

Personally, I didn't get oil into my air filter - although it's probably of an oil-soaked-sponge type anyway!

Okay, scrub that. According to the manual it's a sponge type that you wash with a bit of detergent. And then check the oil and fire it up.

Health and safety afterthought. You did disconnect the HT cap from the spark plug before you got down and dirty with the blade, didn't you? The odds of it firing up accidentally are a million to one, but your fingers are worth more than that.

BJ

[XFool]

...Well as you are here.

Could anyone of experience suggest anything here? An allotment I am part of purchased a new Briggs & Stratton engined Qualcast mower from Homebase. It originally worked OK, wasn't used for ages (COVID) now simply will NOT start. In theory new enough to still be under guarantee - no point suggesting taking it back to shop. Branch closed down and was bought from liquidators.

I have changed the oil, as advised after first 6 hours use. Nothing. Have checked spark plug - have spark. Have replaced petrol. Absolutely nothing. Shows no signs of life whatsoever.

I too noticed brand new air filter slightly wet with oil, dried it out - but as mentioned it is anyway a 'wet' sponge filter so shouldn't matter.

I have no experience with such machines, so can anyone who has suggest how best to proceed?

'Strimmer' and Cultivator bought at same time and kept in same shed both still fire up (had other problems with those too, but that's another story!)

TIA


PS. Looks likely it is the same engine as used on the OP's mower.

[scrumpyjack]

...Well as you are here.

Could anyone of experience suggest anything here? An allotment I am part of purchased a new Briggs & Stratton engined Qualcast mower from Homebase. It originally worked OK, wasn't used for ages (COVID) now simply will NOT start. In theory new enough to still be under guarantee - no point suggesting taking it back to shop. Branch closed down and was bought from liquidators.

I have changed the oil, as advised after first 6 hours use. Nothing. Have checked spark plug - have spark. Have replaced petrol. Absolutely nothing. Shows no signs of life whatsoever.

I too noticed brand new air filter slightly wet with oil, dried it out - but as mentioned it is anyway a 'wet' sponge filter so shouldn't matter.

I have no experience with such machines, so can anyone who has suggest how best to proceed?

'Strimmer' and Cultivator bought at same time and kept in same shed both still fire up (had other problems with those too, but that's another story!)

TIA

I have often found that a dead machine can be revived by taking out the sparking plug, tipping a few drops of petrol in then putting back the plug and try and start. This usually works. If you leave a petrol machine for a long time you can get the problem of 'stale fuel'. The higher octane elements in the fuel evaporate and then the machine won't start. My mower service guys have often told me that was the problem.

[bungeejumper]

Brand new petrol? Would be my first thought. It loses its top octanes in the can during storage.

Next up would be a bit of WD40 on the plug lead. It might be visibly sparking, but it might not be delivering quite the full jolt. Does the lead foul the fins anywhere?

Failing that, you've very likely flooded the cylinder with all that pulling. Take the plug out and give it 15 mins to air-dry itself. Then try again.

BJ

[XFool]

I have often found that a dead machine can be revived by taking out the sparking plug, tipping a few drops of petrol in then putting back the plug and try and start. This usually works. If you leave a petrol machine for a long time you can get the problem of 'stale fuel'. The higher octane elements in the fuel evaporate and then the machine won't start. My mower service guys have often told me that was the problem.

OK thanks. I will try this.

Yes, the manual with the machine did mention this problem with the fuel (mentioned possible 'condensation'), which is why I replaced petrol. Unfortunately it was from the same petrol can as the original fuel...

The 'Strimmer' is two-stroke, can't remember about the cultivator.

[scrumpyjack]

Also changing the fuel in the tank doesn't change what's in the carb and the feeder tubes, hence putting a little petrol directly in the cylinder can kicj start things. When you take out the plug you can see whether it is flooded or not.

[Nimrod103]

2 comments:
AIUI all rotary mowers come with instructions not to turn them on their side. If you want to work underneath, tie the handle down, so raising the front of the mower. Easier if on a work bench.
AIUI Modern petrol comes with 5% biofuel added, going up to 10% in September. This bio-ethanol absorbs water, and as others have mentioned can make stored fuel 'go off'. This may make it reluctant to start. If it isn't the electrics, it could o be a blocked fuel line, or a dodgy something in carburettor. There is probably a little rubber bulb to press - is it actually filling with fuel?

[bungeejumper]

Next up would be a bit of WD40 on the plug lead. It might be visibly sparking, but it might not be delivering quite the full jolt. Does the lead foul the fins anywhere?

Can I add a bit to that? It's quite possible for a spark plug to work brightly when it's outside the engine, but to completely refuse when it's inside the pressurised environment of the cylinder itself. That can be maddening!

Unless the plug itself has a cracked insulator (which is unlikely on a newish mower unless someone's dropped it ), it can fail to give its best because of 'tracking' - which means that black carbon deposits on the plug have built up to the point where they can actually short-circuit some of the electrical jolt - which makes the plug less happy to spark when it's under pressure. That's why old-fashioned spannermen carried those tiny wire brushes for cleaning the ceramic cores on the spark plugs.

Here's hoping that you don't need to do all that. Modern engines don't suffer from black carbon fouling on the plugs unless they're really knackered, or unless they've been flooded by repeated unsuccessful attempts to start them. A healthy plug is pale grey or brown. But not white, which means it's running too hot.

BJ

[servodude]

Since the discussion has come round to fuel "going off", I recommend using this before winter storage -

https://www.screwfix.com/p/no-nonsense- ... 50ml/9631x

RVF

And when you take it out of storage a couple of squirts of this https://www.nulon.com.au/products/aerosols/start-ya-bastard-instant-engine-starter will normally help it kick in if the petrol has lost the top notes

- sd

[XFool]

Quick update.

I was all prepared to try again with some fuel fed directly through the spark plug hole. In the event I learned the woman concerned had taken the mower to another supply outlet and got her money back and has either bought, or is going to buy, another mower. So we will never know.

Though there is always next year...