meltd melt off here. he left the propane on too long building up and igniting. to find out how powerful a blast can be we set up a demonstration. we opened the gas valve to simulate a leak. i can smell it now. after a few minutes. 3, 2, 1. did you see that fire ball? she just went down. that could be you standing at the grill. a giant ball of fire erupting from the grill. so that was nbc s jeff rossen reporting. fire officials say that you don t want to keep pushing the igniter button on your grill. if it doesn t start make sure that the grill lid is open. shut off the gas and try again later. another sip, the soapy water test. use a spray bottle filled with soapy water and spray it on all