Plug fouls out turns black and starts to backfire

did you foul the plugs , this is something that happens all the time when you have a hand choke on something , when it gets cold out you are going to need more choke, the best thing to do when it is cold is to warm it up do not just take off because you always leave the choke on and foul the plugs, warm it up leave it alone , do not fix something that is not broke

I would remove the float bowl bolt and run a piece of wire through the holes to make sure that there are no clogs.

Is the gas fresh?
Possibly stale gas is the problem
http://www.clarkeservice.co.uk/manuals/generators/g900.pdf

Has engine been serviced: clean air filter, fuel filter, spark plug.
Clean out fuel system with carburetor cleaner. Place about 12 oz. in fuel tank and run engine.

Hi Joe, I had asked for a little clarification and have not received any information. I will answer this question based on the generator is in good working order and it is a recoil start. Open the petcock, (this is the fuel valve) and give it about a minute to fill the fuel bowl on the carburetor. If your generator has an engine an on/off kill switch, set to on. If the generator has an auto idle switch set it to off. If the engine has a throttle lever located under the carburetor, push it all the way down (full throttle). Pull the choke knob out completely, there is a detent on the choke for half choke, pull it past this for full choke. pull the recoil starter rapidly. As soon as the engine starts running push the choke knob to half choke, this will allow the engine to run smooth while it's warming up. Depending on the climate that you are in, warm up time will vary. After a minute or two in cold climates start pushing the choke knob in, if it starts to run poorly pull it back out too the half position and let it warm up some more. When you can posh the choke in without the engine faltering it is ready to go. In warmer climates you might be able to start the engine without the choke or in the halfway position. Robin Subaru makes some of the finest small engines available. I would choose a Robin over a Honda every time. I hope this gets your generator going, and once again this is based on the generator being in good working order. Good luck, Michael Burke.

NGK plugs dont stop, especially all at once, so there is another problem.
There are some resisters in the plug caps that can fail.
Are the plugs carbon fouling?(dry black) if so make sure the air filter is new, and oil is changed.
Does the enginge blow smoke or use oil?(wet black)oil fouled may mean rings.
Fuel fouled may mean the jettting is wrong or choke stuck open
Its the battery good(new) and charging ,put a multi meter across the terminals 12v stopped, 14v running approx.
it always helps to drain the carb bowls every few weeks
If exhaust is not standard, the jetting may be wrong.
does the fuel tap work correctly? only use the run or res positions never pri
A short in the kill switch or a worn ignition switch can cause a miss or backfire

There should be a vacuum hose diagram on the underside of the hood. Try plugging any leaking hoses to get it to run decent first, could have a fouled spark plug for the missing problem or a bad spark plug wire. As for why it won't crank cold, is the battery any good? Has to be charged up good to crank the engine over and fire the spark plugs. As for the choke not working, is it electric? If so, check for power at the choke thermostatic housing, the round black thing, should have a wire going to it that needs power to warm up the choke thermostatic spring.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/michael_2496c4f07ad24453

if you are running the engine at full CHOKE, then it is flooding the engine, but if you meant off full choke, then the carb is still stopped up. Try soaking in carb cleaner overnight after removing jet & all rubber goods. HOPE THIS HELPS.

If you have good spark, clean air filter (replace anyways), try choking it half way or so. If it runs better, then it is running too lean, probably a clogged orifice or jet in the carb. If choking it makes it run worse, then it is likely running too rich. Could be a float problem, or metering tube that is clogged and isn't spraying.

Don't use cold start.it will not solve your problem.Try running it with out the air cleaners ,it may be that you have an air intake problem and not getting the right Air / fuel mixture .

Where can i obtain a manual for the 5500 gas generator