Failing all the advice above you may have to take it out and start again. Did you use exhaust paste between the induction/exhaust system?? A bit may have got stuck in the system. Is the vent inside the bus clear?? Is there anything that may have been sucked into the unit via the suck side.
When I installed mine i interpreted the rules as "don't shorten either pipe but you can lengthen the flue so long as both together are under 2 metres. The attached is a quote and it does say tubes (plural) may not be shortened. Best of luck sorting it out. A 0.75 metre length of 22mm flexible stainless steel tubing with a special end cap is supplied for ducting the products of combustion away to the edge of the vehicle. The tubes may not be shortened but can be extended for certain applications WIRING INSTRUCTIONS A “P” clip is provided for fixing the end of the pipe to the underside of the vehicle with the end cap slightly protruding under the sill or bumper and pointing towards the rear of the vehicle. The maximum overall length of the flue and inlet pipe combined can be up to 2 metres if required. However, the flue pipe should never be shorter than the combustion air inlet pipe.
disconnect the long ex pipe and try it if it works my guess is. The bend on the pipe has the effect on the flow so your 2m pipe with a bend is more like 2.5m pipe
Thanks for all you suggestion gents Birdy as I had it running twice for about 20 mins on this gas bottle I'm guessing that its not overfilled but I will let a bit out just in case The pipes were standard lengths when I tested it so you lot maybe onto something there. When I installed it I shortened the air intake by about a quarter, I only shortened it more because it took a bit of damage near the top which is why I cut it shorter. I do have the original Ali exhaust pipe which was too short for the exhaust so I bought a longer one, I could use this one for the air intake. I think I'll try scoopers idea first cos will cause me less drama. I may speak to someone at propex about the length of the air intake before I rip it all out again I wish I had put it under the frickin rock n roll bed now, it would of been easier to install and less drama with the pipes. Thanks for all your suggestions k+ to you all. I'll update when I have some good news and hopefully someone in the future may read this thread and avoid being a numpty like moi
My Truma also senses the intake air, and if any combustion fumes are detected, it will shut off so nothing nasty is pumped into the vehicle, I believe most new systems have such a safety feature, intakes should be away from and above exhaust
From the manual "cutting off the gas supply to the burner and causing the heater to be switched off by the electronic flame failure system. The operation of this cut-out could be caused by either a restricted hot air outlet or air inlet, or the heater being switched off by a battery isolating switch depriving it of its purge cycle."
I had a similar problem with my old propex1600, It would go through the start up and fire for approx 5 sec then cut out... The cause was found to be a blockage in the gas line, right where it connected to the unit. I'm guessing that there was enough initial gas pressure for it to ignite, but then the pressure decreased causing flame failure. check all connections,
If you're really stuck, give Propex a call. They're said to be very helpful. (or prove you're a man and buy an Eberspacher )
Have you tried re-setting it? I had some probs with low gas supply and with low voltage but a re-set seemed to cure both and it's been OK ever since!
