I have a Mahindra 3510 3cyl, 34hp. After setting for a month we started it and it smokes out the exhaust and makes a loud popping noise near the back of the engine on the right side. It does quit smoking for a while the starts smoking again. Drained fuel and add 5 gal new with a fuel additive and ran it for about 2hrs. Still popping. 550 hrs. on engine. We did find a mouse nest in the area of the popping and cleaned it out. Oil ok, Air filter ok and radiator ok