carburettor bowl

[gianjeep]

hello guys
recently my jeep at idle speed was up and down,and i've problem to find a correct carburation,so i check the carburettor and i discover the bowl is full of petrol inside,how is that possible without any evident fracture or broken parts where the fuel goes into????

[wesk]

Not sure what you are describing? The bowl is suppose to have fuel in it. The carb float level controls the height of the fuel in the bowl. If you have the bowl overfilling then that is usually caused by a stuck or leaking inlet valve plunger, or a float that has holes and has filled with fuel making it to heavy, or excessive fuel pump pressure forcing fuel pass the inlet valve.

A fluctuating idle can also be caused by a worn throttle shaft opeing that lets varying amounts od excess air in when the shaft bounces or moves around during operation.

[gianjeep]

sorry... carb float level with hole....
can the fuel overpressure bend the floating bowl?
if the fuel pump is fill with petrol on the other side of metering road jet (spring side)causes failure?
i notice blak smoke when the jeep run idle after a minute running....
so i suppose someting wrong in the low speed jet but i'm not sure...
yesterday i've replace the venturi but no difference ...after a minute a little blak smoke come out (exoust) and the engine sound is rough and grumpy..any suggestion.. thanks a lot..
gian

[wesk]

The float can be overpowered by excessive fuel pressure.

The float can leak and get too heavy allowing the inlet valve to stay open.

The inlet valve plunger tip can have foreign material on it or be damaged and not seal correctly.

Is this a brand new problem that just occurred with nothing done to the jeep recently that may have caused this problem?

[gianjeep]

thanks wesk for your support and detailed reply,
i've found a failure in the idle screw,replace and now the engine sound it's like a ferrari.....