Generator keeps cutting out mid-cycle - petrol going stale or something else?

Had almost exactly this with my Honda EU22i last summer — convinced myself it was the carburettor jets blocked with stale fuel, stripped the whole thing down, cleaned everything spotless, and the fault came back within a week.

Turned out to be the oil level sensor playing up. Engine would run fine for 20-30 minutes, warm up, then the sensor would give a false low-oil reading and cut it dead. Classic symptom is it restarts no problem once it's cooled slightly — does yours do that?

A few things worth ruling out in order:

• Fuel age — anything over 30 days in the tank can gum up the carb needle valve on smaller generators. I now add Briggs & Stratton fuel stabiliser if it's sitting more than a fortnight
• Air filter — mine gets mucky surprisingly fast when running near the garden office
• Load spike — what are you running off it? My inverter charger (Victron MultiPlus) occasionally pulls a nasty startup surge that trips cheaper generators under a certain load
• Earthing — sounds odd but a poor earth connection can cause all sorts of phantom shutdowns

The stale petrol theory is worth pursuing first because it's cheap and easy — drain the tank completely, run the carb dry, fresh fuel in. Ethanol-free from a decent forecourt if you can find it.

What make and model is it, and roughly how old? That'll probably narrow it down considerably. Others on here have seen similar with certain Hyundai and Kipor units that have known sensor quirks.

@JennyThomas57 classic case of "I'll just have a quick look" turning into a full engine rebuild on the patio at 11pm with a head torch and three mystery bolts left over 😄

Before you go full carburettor surgery again — have you checked the low oil shutoff sensor? Honda's are notorious for tripping it

@JennyThomas57 Had something similar with a Yamaha EF2200iS at the static — stripped the carb twice before realising the actual culprit was a failing capacitor in the AVR board. The generator would run fine under no load, then cut out the moment something like the fridge compressor kicked in and drew that initial surge current.

Worth checking your load profile during the fault. If it's consistently dying at a specific point in a cycle — compressor startup, kettle element switching on — that points more toward a regulation or surge-handling issue than fuel degradation.

Stale fuel absolutely can cause intermittent running, but it tends to present as rough idle and hunting rather than clean cutouts under load.

@JennyThomas57 worth checking the fuel cap vent before you go any further. Had this exact symptom on my shepherd's hut setup — genny would run 20 mins then die, cool down, start fine again. Classic vapour lock from a blocked cap vent.

Tiny hole, easy to miss, took me an embarrassingly long time to find it. Just loosen the cap slightly next time it cuts out and see if it immediately restarts.

Also on the stale fuel point — I now always run mine dry at the end of season and store with a bit of Briggs & Stratton fuel stabiliser if I'm keeping any in the jerry cans. Saves a lot of grief come spring.

@Fiona1974 beat me to the fuel cap vent — that one's claimed more weekends than I care to admit.

I'll add one nobody mentions: the spark arrestor on the exhaust. Gets clogged with carbon, engine runs fine for 20 minutes then slowly suffocates itself like it's making a dramatic point. Pull it out

@Fiona1974 @PanelSteve already stole my thunder on the fuel cap, so I'll throw in the other classic time-waster: check your spark arrestor isn't clogged, mine on the van genny was basically a solid carbon biscuit and it'd run beautifully for 20 minutes then wheeze to a halt like a pensioner on a steep hill.

@FellGraham spark arrestor on the exhaust is another one that'll have you knee-deep in carb cleaner before you realise the poor thing just couldn't breathe out — had my van's genny doing exactly this last August, sounded terminally ill, turned out to be a fluff-and-carbon party in the arrestor mesh.