I am trying to get my yanmar 1802 back running. I had the starter tested and it had gone out. I had it rebuilt and tried to start it. When I hook my jumper cables up to the leads nothing much happens. I did hook the positive to the starter stud and was able to get it to start to turn over. When I pulled the decompression handle out the engine free spins no problem. So I figured it has to be air or fuel now. Took the air filter off which I had recently replaced and it still seemed fine. In the past I have changed the oil filter and bled the fuel lines. It has ran since then. Could air make its way back into the fuel line if it has never ran out of gas? Only other thing I could think is the exhaust is clogged. Any ideas?