Engine surging at idle after cleaning carb and installing new gaskets

OutbackL130 · Oct 1, 2013

My 420 engine surges at idle and I have to pull the choke partly out to make it idle smoothly. This is after I removed the carb, dismantled, cleaned and reinstalled with new gaskets.

The john deere dealer had trouble locating the correct parts for my old engine. I did have to reuse the carb to manifold gasket because they sent one that didnt fit. Actually, all the gaskets were a problem to find for my onan B48G. The main carb gasket didnt fit perfectly either. There was a slight gap around the corners of the carb where the gasket was too short. It matched the basic shape of my carb and fit around all the orfices so I went ahead and used it.

How are you able to tell if the surging is gasket related?

Sysop · Oct 2, 2013

Connect a tube to the carb to use as a "snorkel" for clean air, start the engine cold, immediately spray around the carb with some carb cleaner. If there are gaskets leaking enough to draw air in and mess the ratio up, it's leaking enough to draw the carb cleaner in which will cause the engine to stutter or stall. I've found many intake gasket leaks with this method.