The 3 most common part(s) or condition(s) which cause the symptom Small engine leaks gas are listed below starting with the most likely. Check or test each item and watch any available videos.
RepairClinic Item # 1602549
If the small engine leaks gas the carburetor gasket on the bottom of the carburetor might be dried out or missing. If the leak is coming from the bottom of the carburetor, try replacing the carburetor gasket.
RepairClinic Item # 2304781
If the small engine leaks gas, check the fuel lines. If any of them has a crack, replace it, don't try to repair it. If any of the fuel lines are dry or cracked replace them completely, don't try to cut off a piece and reattach it because the rest of the tubing might also have cracks or defects.
RepairClinic Item # 1602609
If the lawn mower does not start, the carburetor might be clogged or have bad fuel in the float bowl. If old fuel was left in the lawn mower for a long time some of the volatile ingredients may have evaporated, leaving a thicker, stickier product that is more like varnish or shellac. This sticky fuel can clog up the small jets and ports in the carburetor and it can be difficult to burn making it hard to start the engine. The only solution is to drain the old fuel from the float bowl and thoroughly clean the carburetor with carburetor cleaner. If that isn't effective, the entire carburetor may need to be replaced.