Scoutmaster Hank Manz has written a useful document on how to light and operate a Coleman camp stove. It’s linked on the Resources page, and also available here.
The key point to remember is that the stove has to go through a startup period of a minute or two where the fuel is mixed with air and warms up to the operating temperature. If you fiddle with the stove before it’s fully warmed up, then it just won’t work right. If that happens it needs to be shut down, cleaned out, and restarted.
So the moral is: DON’T MESS WITH THE STOVES UNTIL THEY’VE WARMED UP!
And study Hank’s notes.