Generator won't start in cold weather - flooded carb or something else?

Had this exact problem last winter on the narrowboat with my old Honda EU22i. Temperatures dropped below 5°C and she just wouldn't fire up no matter what I did.

Turned out to be a combination of things rather than one single culprit:

• Carb flooding - yes, this was partly it. Choke on too long in the cold makes it worse than you'd think
• Stale fuel - petrol degrades surprisingly fast, especially with ethanol content. Anything sitting more than 4-6 weeks in the tank was causing grief
• Oil viscosity - thicker oil in cold temps makes the pull-start feel like dragging treacle, and the engine struggles to turn over properly

What actually sorted it for me was draining the carb bowl, using fresh fuel with a shot of Briggs & Stratton fuel fit additive, and letting the engine warm slightly in the engine bay before attempting a start. Also switched to a 5W-30 synthetic rather than straight 10W-30.

One thing I'd check - is the choke butterfly actually closing fully? Mine had a sticky mechanism that wasn't giving full choke when I needed it.

Has anyone found a reliable method for generators stored externally in winter? Mine lives in the stern locker which gets absolutely brutal in January. Wondering whether a small engine block heater is worth the faff for occasional use, or whether I'm better off just keeping the carb drained between uses and accepting the longer startup routine?

Also curious whether anyone's had similar with diesel generators - my neighbour on the next mooring swears by his Stephill but I'm not sure how they handle the cold comparatively.

@MultiPlus_Queen interesting timing, I'm dealing with similar on my boat right now with a Kipor 3000.

Few things I've found that make a difference below 5°C:

• Choke discipline — full choke, don't touch the throttle until she fires
• Old or degraded fuel is massive culprit in cold starts, ethanol-blended petrol goes off faster than people realise
• Let the engine warm at idle for a good 2-3 minutes before putting any load on it

Also worth checking your spark plug — cold weather exposes a weak spark that wouldn't bother you in summer. NGK plug swap sorted a persistent cold-start issue for me last February.

What fuel are you running? If it's been sitting in the tank since September that could easily be your problem before anything else.

@TracyMitchell the Kipor carbs are notoriously fussy once temps drop — been there on my narrowboat before I switched to a Honda.

One thing nobody mentions: choke position matters more in cold weather than people realise. Full choke, but only blip the throttle once before cranking. Over-priming is usually what floods it.

Also worth checking your fuel line — diesel boats nearby can forget this doesn't apply, but petrol sitting in an unheated locker goes slightly waxy in composition at low temps and flows sluggishly.

My current ritual below 5°C:

• Drain the float bowl the night before if I know it'll be cold
• Keep a small 12V heat mat (nothing fancy, Aldi jobbie) wrapped round the carb housing overnight
• Fresh fuel from a busy forecourt rather than old stock

The heat mat trick genuinely transformed my cold starts.

@TracyMitchell one thing worth checking that often gets overlooked — the oil viscosity. Most of these generators ship with 10W-30 or even straight 30W, which becomes quite thick below 5°C and puts enormous strain on the starter circuit. Switching to a 5W-30 synthetic made a noticeable difference on my setup when I was still running a petrol generator for the garden office before I went fully solar.

Also worth checking the choke mechanism itself — the butterfly valve can stick due to corrosion or a worn cable. Not a flooded carb symptom necessarily, more a cold-start enrichment failure.

If the Kipor is pulling proper current from the starter motor but just not firing, I'd lean toward fuel delivery rather than electrical. A carb ultrasonic clean over winter is worth doing annually on these cheaper units regardless.

Does anyone know if there's a difference in cold-start behaviour between the pull-cord carb-fed generators and the inverter-style ones? Asking because I've got a small Honda EU10i running occasionally in my shepherd's hut during winter and I'm dreading hitting this problem.

It lives outside under a cover — wondering if keeping it somewhere slightly less exposed (even just out of the wind) makes a meaningful difference before it even gets to the carb/oil stage @CarlBaker mentions?

Also curious whether a fuel stabiliser like Sta-Bil in the tank during low-use periods helps or makes cold starting worse — seen conflicting advice on this.