Small Engines (Lawn Mowers, etc.): Onan Generator, float bowl, fuel flow

Question
I have an Onan E450 small portable generator that is old as the hills and of course all the parts for the thing have long since been dis-continued and they are no longer available.

My problem, which was a small one, started out with trash and rust dust that had clogged up the shut-off valve and screen. I had taken this apart and cleaned it very good and replaced it. Then to be on the safe side, removed the bowl on the carb, found dirt in it as well. Removed the carb and found that at some point someone had tried to remove the main jet, which is located in the bowl nut. This nut looks like one from a Tecumseh that has the holes in it for fuel flow into the jet. This jet shows signs of nicks and stuff from a screwdriver or something. Keep in mind that this generator ran perfect before the fuel flow was stopped up by the trash.

I cleaned all the parts of the carb, used a small piece of tag wire for the small holes, used carb cleaner and then air pressure, carb looks almost new, but heres the problem I have:

The engine runs, but is now fuel rich, adjustments on the air mix screw makes no changes to it. If I turn the fuel shut-off valve alittle, the engine will smooth out and run perfect for a few minutes and then shut down. All passages in the carb are clear, no signs of dirt anywhere, just can't control the fuel flow, so how do I solve this problem ?

Charles


Answer
Because the mixture screw makes no difference, there is either a blockage inside the carb still or you may have an issue with the needle/seat/float not properly controlling the fuel level inside the float bowl.  You can inspect the inlet needle for wear (groove) and replace as necessary.  The seat, if replaceable, should also be changed when the needle is changed.  Check the float for saturation (if you shake a brass float, you will hear fuel inside it if it is leaking).  If it is a composite float (black), it will feel heavy and will not float if it is saturated.  Replace as necessary.  You will also need to make sure the pivot pin and float operate freely without binding as this can also cause uncontrolled fuel flow.  Hope this helps.