Buzzing sound from engine

[Zeek90]

Hi guys. My 77 B210 been making this annoying loud buzzing sound like the sound some older cars made when ud open the door. An the buzz would change like higher an lower in pitch sometimes. It  Sounds like its coming from Where the carb is like around the manifold idk. Also i been getting some slight smoke behind the carb after idling for a while an revving nothing bad tho. Anybody know where that buzzing would be coming from?🤔

[datzenmike]

Idle cut solenoid? Have someone turn the ignition to ON (don't start it) then OFF, ON, OFF and listen near the carburetor. You should hear a soft clicking. Is the idle cut loose?

[Zeek90]

i found out that its that valve that is to the left side of the baby blue bracket that is holding the air air filter cover . Its got a rubber cap on it . Its in between the air filter bracket and the rubber hose that goes into the air filter. Idk the name of that part. Can you help me with the name? For i could look for a replacement? I found out it stopped making that winy noise when i plugged up the lil rubber hose that connects to the bottom left of the air filter cover. Id plug it an it stopped making noise.  Thank you for the help. 😊 But my motor was idling a tad rough also. I checked the motors compression an they were roughly all 150lbs. No wet spark plugs either.  Pertty weird. But Thanks for the help again.

[datzenmike]

Just because something makes noise doesn't necessarily mean it needs replacing. Something else may be causing this.

 

 

It looks like the fuel shut off switch. It's activated by intake vacuum. Does it have 3 wires to it in the back? If it does, check that the small hose to it does not have any cracks in it and that it is firmly connected.

 

If it is the fuel shut off, it's job is to temporarily shut off fuel to the idle circuit by opening the idle cut solenoid during deceleration when intake vacuum is highest and the throttle is closed. Idle fuel when the throttle is closed is not needed to keep the engine running and is simply wasted out the exhaust as a hydrocarbon emission. There is a clutch switch in line as well so the engine does not stall during a down shift. Long before the engine gets to a lower or idle speed, the vacuum signal lowers, the fuel cut off switch closes, the idle cut solenoid opens and fuel for idle is returned. It's an emissions device that actually saves gas and only works when you are slowing down suddenly. 

[Zeek90]

On 6/26/2019 at 5:53 AM, datzenmike said:

Just because something makes noise doesn't necessarily mean it needs replacing. Something else may be causing this.

 

 

It looks like the fuel shut off switch. It's activated by intake vacuum. Does it have 3 wires to it in the back? If it does, check that the small hose to it does not have any cracks in it and that it is firmly connected.

 

If it is the fuel shut off, it's job is to temporarily shut off fuel to the idle circuit by opening the idle cut solenoid during deceleration when intake vacuum is highest and the throttle is closed. Idle fuel when the throttle is closed is not needed to keep the engine running and is simply wasted out the exhaust as a hydrocarbon emission. There is a clutch switch in line as well so the engine does not stall during a down shift. Long before the engine gets to a lower or idle speed, the vacuum signal lowers, the fuel cut off switch closes, the idle cut solenoid opens and fuel for idle is returned. It's an emissions device that actually saves gas and only works when you are slowing down suddenly. 

Yes that part does got 2 hoses that run towards the carb and one hose that is on the right of the part on the side. Ima replace those vacuum hoses an see if it does the trick. Thanks