Our '04 DF140 started surging after being run completely out of gas. Replaced the firewall water seperater/filter and did not help. Got a set of plugs and took the cowl off to see the small filter between the pump ball and fuel pump (I guess it's the pump: round Mikuni thing bolted to aft surface of engine next to 3-4 plugs) had some nasty stuff in it. Removed the filter and blew it out, flushed backward with some gas. Tested the pump ball with line off filter and good. Old plugs (5 years) looked great. Put in new ones and test drove. Ran great!!! Thanks for the help, C.
