1997 P38 4.6 on LPG: Backfire

My P38 is fitted with a single point induction LPG system, and it also runs a cone type air filter. The other day, the water hose to the vaporiser blew off (loose jubilee clip I think). I stopped quickly, there was about a litre of water lost but everything started and ran okay. I was Green Flagged home (the shame!) where I re-connected the hose and it started and ran okay in gas and petrol. I took it out for a test run, and after about 100 metres there was a loud bang. I pulled over and found that the water hose was okay, but the end of the cone air intake filter had blown OUT!:doh:, and the air intake duct at the plenum had worked loose. If I didn't know better I would say that there had been some sort of detonation in the air intake where the LPG enters the system. All other hoses and parts are intact.

Should I just screw everything back together and give it another try, or do you think it's time for the professionals. LPG makes me nervous at the best of times.

p.s. To bleed the water system, do I just let it idle with the top off the expansion tank and let any air bubble round, or is there another way of doing it.

I would be grateful for any advice, thanks everyone

How much Gas do you have in the tank???

The single point systems are prone to backfiring when the gas level gets low due to lck of pressure....

Look on the internet for a backfire valve (sometimes refered to as a fart flap) as this will save the exepensive MAF from damage....

If you have plenty of gas in the tank, I'd go see a LPG installer for a once over, sometimes running lean can cause backfires too....

Thanks for that. It's about 2/3rds full. I think you're right about seeing the experts. Any idea how to get the air out of the water system though?

Junk it and get a multipoint front end system.

Single point systems backfire cos the mixture is too lean. See specialist and get it reset cos it can do damage to MAF and throttle butterfly. When mine backfired, it blew the airbox to bits (with fart flap in it!) and didn't half make the bonnet jump! Mind you the guy in the Merc I was passing jumped higher, tee hee!

Cheers. The code turned out to be the Camshaft position sensor. I'm going to take it out and check the wiring as a lot of the plugs have chaffed insulation. We'll see how that goes. My wife heard the backfire in the house half a mile away!