When I changed my metering head I had a problem of over fueling, tried every thing with no joy then someone on here told me to check the control plunger wasn't sticking, it's located underneath the metering head you can take it out without taking the fuel lines off so there's no need to replace the crush washers, just undo the metering head lift it onn the housing the undo the nut underneath take the pin out and clean it with carb cleaner, it seemed to work fine after, if that doesnt work could be the cold start valve fooked, but dont hold me to that.