Carb not holding fuel?

[datzenmike]

I recently replaced the intake/exhaust gasket on the L20 because I noticed a leak. So now the engine will start and run for about 2 min and then will Rev up rpms close to 2000 and shut off. Luckily I have the glass sight on the Hitachi carb so I can see that the fuel bowl will fill when I first turn the key...start it and it quickly just empties. When I turn the key again it won't refill. If I wait a while it will refill again but it seems to be intermittently. I pulled the fuel inlet and checked the needle valve and cleaned all the components but that didn't help. I can see through the sight glass that the needle valve seems to be functioning the way it should. Fuel pump is working fine. Just replaced the fuel filter.

So...ideas?

Clogged fuel line? I was seeing something about vapor lock (it was sitting awhile while I was replacing the gaskets.) Possible vacuum leak still on the int/ex mani?

Any suggestions would be of great help. Thank you!

[JWray707]

There is no vacuum inside the float chamber. Gas only goes into and fills the carb, never the manifold.Usually a cleaning and make sure there is nothing stuck in it that will prevent it opening. A carb rebuild kit will usually have a replacement needle valve.

 

There is a glass on the front of the carb float chamber. Gas should be seen at the half way dot on the glass. Have you taken the front off the carb? Maybe the float is stuck in the up or closed position????

Good to know, thanks Mike.

I've disassembled and cleaned it multiple times. Could be the rubber tip is getting caught in the plug hole and I just can't see it.

I had an old full glass sight cover I put on so I can see everything. The float will drop and rise with the gas level and in turn the needle valve (at least the peg end) will too. Gas fills up to the line (when it does fill).

I'll look into a rebuild kit to try out a new needle valve.

[bob3d]

Is there a return fuel line? See if it has a small orifice that may be clogged.  Take off the rubber hose and look at the metal tubing. I never noticed it until recently on mine.

[datzenmike]

 

Small hole on end of pipe going to the return hose. Near the fuel pump.