Whether you're using a 20 Lb Propane Grill Tank or a screw in gas canister, the solution to the problem is the same .
1. Be sure you have enough gas in the tank or canister to maintain proper ignition.
2, If the above checks out OK. Turn the LP tank valve OFF or if you're using a screw-on canister
turn the gas valve OFF.
3. Disconnect the hose from the tank or unscrew and remove the gas canister.
4. Wait 5 minutes and reconnect the hose to the tank or reattach the canister to the gas valve.
5. Open the gas valve VERY, VERY SLOWLY (Slow Motion, slow). Once the valve is full open, light
the burner & turn it to HIGH. Did the burner light and does the flame height look correct?
If so, you solved the problem. Remember to always open the tank valve Very, Very Slowly.
if the above didn't solve the problem, you will either need to replace the Hose/Regulator Assembly or the Gas Valve/ Canister Holder. The Hose/Regulator Assembly you can pickup from any home center or hardware store that sell grills & accessories for about $30.00. If it's the Gas Valve/Canister Holder, you will have to purchase that from Weber or from Factory Appliance Parts http://www.appliancefactoryparts.com/gasgrillparts/brands/weber/q200.html
Part # WEB4195 ($29.99) The adapter hose is also available there if you want to make it a one stop shop for $32.99
I hope ths helped you and thanks for choosing FixYa. Happy Grilling!!