Burner lights and goes out - won't heat water.

It is a well known issue. Lots of help here in text and videos.

https://www.google.com/search?q=Patio+heater+won%27t+stay+lit.+Pilot+ok+but+heater+burner+goes+out+in+10+seconds

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There's a temperature sensor in there. If the pilot light goes out, you don't want the main burner to come on and release gas.

Make sure thermocouple tip is seated inside the burner flame.
Make sure thermocouple is not overtightened. Finger-tight + 1/4 turn.
If the pilot lights, then ECO energy cut off is not tripped, but gas control valve might be bad.
Check color of pilot flame: it should be strong and clear blue.
If pilot flame is weak, or color of flame is yellow-orange: Clean pilot orifice and burner and combustion parts on yearly basis.
Clean air intake screen if applicable.
Increase air supply to water heater. Open a window and see what happens.
Check for adequate draft going up chimney using match under vent hood to see if smoke drafts immediately upwards.
Bleed air out of gas line.
Check gas pressure.

Open following links for troubleshoot resources:
http://waterheatertimer.org/pdf/Pilot-light-will-not-stay-lit.pdf
http://waterheatertimer.org/pdf/Pilot-outage-troubleshooting.pdf
http://waterheatertimer.org/pdf/Vent-spillage-test-atmospheric-gas-water-heater.pdf
http://waterheatertimer.org/How-to-install-gas-water-heater.html#troubleshoot

Infrared burners requite that the gas control knob be held in for 2 minutes or so, to allow the thermocouple on the infrared burner to heat up completely. If it's windy were you are, the wind can blow the burner out, while trying to light it. That's why it has a thermocouple on it, to stop the gas if the burner goes out. All cooking on the rotisserie is doon with the lid/hood closed, at temperatures around 250 degrees F. Once the infrared burner turns bright red, release the control knob.

Hope this helped you to get it lit. Thanks for choosing FixYa.

You need to replace the thermocouple.
When you light the pilot it is supose to heat the thermocouple.
the thermocouple produces a small electric current which allows the gas valve to open and keep the pilot going. and allowing the main burner to come on.

Sounds like the burner flame may be too strong (jumping out from burner tube) . Some people think the louder the better, but that is not correct. When burner shuts down like that, it has a tendency to snuff out pilot as well. Adjust your air shutter at burner so that the flame is a nice blue, or with just a hint of orange/yellow at the tip. Whatever setting that keeps the flame solid from burner tube, and not a big gap between tube and flame. Signs of soot (black) up the cover, or side of trailer means it's running too rich, and you've gone too far thus needs more air. Keeping the flame blue but still right out of the burner, actually heats better, is quieter, and should eliminate that pilot getting snuffed out. Pilot should also be a nice blue flame as well. There may be a problem with positioning of the burner tube as well, but doubtful if it has been running well in that position before. Let me know what happens.

Since the pilot light stays on, and the main burner comes on momentarily, then goes out. This mean to
say that the gas supply is not steady, it also goes off.
You got to get your gas valve repaired or replaced to get
it working.

The pilot assembly should look similar to the pic above. Depending on where you live, you may be required to hire a certified plumber to replace the parts. If not you can do it your self. Keep in mind if it's not staying lit you also need to check the thermostat and the thermocoupler before replacing the pilot assembly. There is a good chance it is just the thermocoupler going out. It is one of the first things to check when troubleshooting a pilot light problem with a gas water heater. A thermocouple determines if the pilot light is lit. If it's not lit, the gas valve fails. If that's the problem, replace the thermocouple.

1. Shut off the gas valve on the water heater and the gas valve on the line near the heater. Remove outer and inner doors, and loosen the pilot and supply tubes and the thermocouple connections to remove the burner assembly.
2. Step 2 Loosen the screw holding the thermocouple to the bracket. Remove old thermocouple. Bring it with you to the store to ensure you are buying the proper replacement.
   
3. Step 3 Install the new thermocouple. Position the thermocouple so that the pilot flame heats 1/2 inch of the tip.
   
4. Step 4 Reinstall burner assembly in the water heater. Tighten burner supply tube, pilot tube and thermocouple connections. Tighten thermocouple no more than a quarter turn more than hand-tight.
   
5. Step 5 Turn on both gas valves. Check supply tube and pilot tube for leaks with soapy water. If soap bubbles, tighten connections to fix leak. Ignite the pilot light, and make sure the thermocouple tip is heating up. Replace inner and outer doors.
   

pilot needs pulled and cleaned