Weber Carb Runs Rich

[Myron]

Hello,

My 2.25 gas engine is running very rich. I am using a Weber 34 ICH and the mysterious thing is when the idle mixture screw is all the way in, the engine doesn't stall. Screwing the screw in has no effect whatsoever. Could there be something going on internally in the carburetor to cause this?

Thanks,
Myron

[dmurrell]

Have you cleaned the idle jet? Mine is very susceptible to this type of behavior. All you have to do is remove the big "screw" on the side of the carb and clean the orifice in the jet.

[daveb]

vacuum leak. or the throttle is screwed open past the idle ports. or the mixture screw or its seat are munged up

Hello,

My 2.25 gas engine is running very rich. I am using a Weber 34 ICH and the mysterious thing is when the idle mixture screw is all the way in, the engine doesn't stall. Screwing the screw in has no effect whatsoever. Could there be something going on internally in the carburetor to cause this?

Thanks,
Myron

[Myron]

Thanks for the replies. The carb is freshly rebuilt and I am certain the idle mixture screw and the hole it goes in are clean and straight. I have eliminated the throttle linkage from the equation by disconnecting it. The carb behaves the same way. I like the vacuum leak theory. I guess I'll have to start hunting.

Thanks again.
Myron

[LH Drive]

I found my vacuum leak to be inside my brake booster. Pull the brake booster line and plug it,,see what happens. It'll cost nothing to check.
Other thing is to spray some carb cleaner around the base of the carb and see if that is where the leak is. The idle will change if its leaking.

[daveb]

look at the end of the needle. if there is a step in the point then it was screwed in too hard and damaged. if not it should be ok.

with the engine on idle, place your hand over the top of the carb slowly closing off the airflow but try not to shut down the engine.

if the engine speeds up at all during this process then there is likely a leak.

spray some carb cleaner around all the intake flanges and see if you get a change in idle speed, that is a good sign you have found a leak.

Thanks for the replies. The carb is freshly rebuilt and I am certain the idle mixture screw and the hole it goes in are clean and straight. I have eliminated the throttle linkage from the equation by disconnecting it. The carb behaves the same way. I like the vacuum leak theory. I guess I'll have to start hunting.

Thanks again.
Myron

[singingcamel]

Make sure your float is set right, if its stuck or bad it will dump alot of fuel.