Hyundal Accent explosion

Hello friends, I have a Hyundai Accent 98 I made you install natural gas equipment but when starting it when you were born power explosion towards the valve and multiple admission cover, I already changed spark plugs and high cables could someone tell me to do this? I clarify to this team they did not installed the spark avabator. Thank you very much

That is lack of fuel returns to the workshop to emphasize the LPG system

They took me a similar problem but from an isuzu trooper and the problem was the EGR but it is best to see you who installs it because it must know why it does that.