200A and 202 reproduction
frames back
in stock.

First, sorry for my English, i'm French and i will try to do my best to be intelligible. I have a coleman 236 who fire up very well. When i full open the valve everything is fine, but the light start to go down after 10 minutes. Then i have to pump again to hold the light ( flame ) on. Wherr could be the problem. She should run on at least one or two Hours without to pump it again. Is it the generator ? I didn't feel any gaz or air leak. Thank you for your help.
Is the fuel cap gasket good?  Most need to be replaced if it is the original 3 piece type with the screw in the top. 
Greg -- Fiat Lux!
ICCC Member #1273
Seeker of Canadian Nickel!
Find a five gallon bucket put some water in it pressurize your tank without lighting the Lantern and stick it in the water see if you have bubbles coming out if you do there's your leak. Most common place to leak from his the fuel cap and welcome from Southern Arizona
Gas is what you use for washing parts diesel is for making power!
Why do they have Braille on the keys on a drive-up ATM?
Looking for any lanterns or stoves dated 5/63 or 1/72
it sounds to me like it's running in "Start" mode only. You are not shutting off the air when opening the fuel valve.

First make sure the cap is sealing. If it is and there are not leaks, then check the fuel/air tube inside the tank 
ICCC member #604
Welcome mon ami. There is good advice above. 

I agree, either you are losing air from the fuel cap having old gasket or the internal fuel/air tube and fuel rod are not working as designed. 
"Stop being angry, and forget about getting back at people; do not worry -- it only causes harm." Ps. 37:8
Eye-SEE-C-C Member #1333 -- MilSpecOps #003
"Michigan - from the Ojibwa word “meicigama,” meaning “great water.”
It’s been covered in the posts above, either the fuel cap seal or the air tube not working properly.  
Welcome from Queensland Australia.
Toowoomba Queensland Australia
Mil-SpecOps #1970
Coleman Slant Saver #51
ICCC Member #1826
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