Onan M43. Has been running good but fuel pump was week/bad. Would die once the tank got down to 1/3 tank or so. External impulse fuel pump with the line through the engine cover. Removed the pump and covered the hole with duct tape. Put an electric pump on. Mowed for about 10 min and it started smoking. Found the oil filter was loose - tightened it up with a filter wrench. Cleaned the engine up some and back to mowing. Run another 10 min or so &n same smoking situation. Filter was 1/4 turn loose again. Why does the filter keep coming loose after I covered the impulse hole ? It ran for 1/2 hr or so before with no issue. The vent tube with filter is clean and connected from the top of the engine to the carb air cleaner so it should not be building up pressure in the crank case. Going to check the filter closer in the morning.