the fuel may make it continue to burn but it’s rarely the source of a fire electrical , insulation, sleeping bags , wax oil, oil , and fuel too
It's only an old van, plenty of them around. I wonder how long the guy had owned it and if it had been checked over recently.
I do wonder about all these stories about fire caused by bad fuel lines. In the past on various cars I have sprayed petrol on hot engines and never had a problem it’s just boiled off. I’ve no doubt that poor maintenance can be a large factor but you still need a spark to ignite the fuel.
I would suggest that some of these fires are the result of electrical bodgery. My dad sadly lost his T25 Westie Atlantic to fire while it was just parked on the drive outside the house. That one was definitely electrical.
I have filled the engine bay with petrol on one occasion without a fire - when a fuel hose popped off a fitting because I had tried to bodge a too-large diameter hose on the fitting, it swelled up and softened with the fuel after about an hour of driving. This was because I could not get the correct sized hose on the day I fitted it. The fuel hoses cracked when I first had the bus and were permanently wet with petrol, but it didnt catch fire. You need fuel and a spark - from a loose wire or faulty ignition before you get a fire. I think I sprayed petrol onto a coil that was connected to the distributor, but the distributor cap was lying on the tin...then it caught fire... And paint, its why my welding gloves are so horrible. That warm feeling, turns out the paint and the polytarp behind you are on fire .. again ..
Always worth giving the carb inlet a good tug. Unlikely, but they can come loose. Roughen them up and epoxy them back in.
I had a brass fitting pop out of one of the original duel carbs. It started running rough. I left it running because I thought linkage went wonky, vacuum hose popping off...It was pumping fuel everywhere. No fire.