Just bought a sig mark-2 with a OS FP 40 it had been sitting for about 6 or 8 years changed the glow plug and it started right up but then dies.I think the tank needs to be cleaned out Any ideas on how is the best way to do this?Real thick oil came out of the exhaust when the nose was held in the air.I asume that this was old castor after the fuel had evaporated.