Gas and Oil Home Heating Furnaces - Coleman in-wall spaceheater "pops"

Hi to all from the semi-frozen south. I have a Coleman in-wall space heater. I don't have a user book (do they make them anymore?) so have been trying to use common sense to solve some of the problems the heater is having. There was a very high pitched whining which I narrowed down to the fact that the pilot light was burning full-open. Fixed it. At the same time I turned off another valve which I then discovered I needed unless I wanted to heat the house with the pilot light. The continuing problem with this heater is the loud popping and flash of light (especially apparent at night) when it turns on. Should I turn the one valve (or stopcock) mentioned above so there is less gas going into the heater when it flames on? Or do I have a more serious problem? Thanks for all the help I've recieved from this site.

mamartinek:

The loud popping is not from too much gas, but rather not enough.

You are experiencing delayed ignition, either from a dirty burner, poorly adjusted pilot or a faulty gas valve.

The burner assembly will have to be removed and cleaned.
You would use a stiff brush, a vacuum cleaner and something to probe the openings in the burner.
Caution: You must be very carefull not to enlarge the burner openings by being forcefull.
Also if the burners are cast iron they could be very brittle and be very unforgiving of a bump or knock.

If the burners are ok then the pilot must be adjusted or the gas valve must be replaced.