Q: I have an engine with a two barrel carburetor. It appears to me the 2nd barrel isn't opening. When and what opens the second barrel?

asked by on

The truck idles pretty good when the engine is cool. It begins to run rough when up to temperature and is very slow to respond. I've cleaned the inside and outside of the carb with carb cleaner and I've cleaned and replaced vacuum lines and connections. I've also changed plugs and wires. I'm baffled! Thanks for considering my dilemma.

respectfully, Jim Burquist

My car has 200000 miles.
My car has a manual transmission.

Hi there. On two barrow carburetors, there are two ways that they open. The most common way is through engine vacuum. When the vacuum drops to near zero, the secondary throttle valve will open and operate the secondary jets. Other systems have a mechanical throttle that opens as the throttle is pushed down far to the floor. Check the vacuum hose or linkage to the secondary and make sure that its hooked up. If your vehicle has a vacuum line to the carburetor and there is no vacuum leak, then the diaphragm in the carburetor could be split causing the plunger to not function making the accelerator pump fail on the secondary circuit. If you need further assistance with your secondary throttle on your carburetor, then seek out a professional, such as one from Your Mechanic, to help you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. I have an engine with a two barrel carburetor. It appears to me the 2nd barrel isn't opening. When and what opens the second barrel?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: just had a clutch kit put in hearing throwout bearing

Hi there. From the description you have provided, you have a warrantable problem with the throw-out bearing, given the clutch kit was installed a day ago. It could be, something was installed incorrectly. It could be, the throw-out bearing was...

Q: EGR valve and vacuum

If you got code P0401 for the EGR system malfunction, then the system would need to be tested to see whether or not the vacuum modulator valve is holding vacuum and can control the EGR valve. These tests are needed...

Q: Battery light comes on and off replaced battery and altenator tested good at AutoZone?

If the battery is new and good, and the alternator is good and charging, the problem may actually be in the ignition switch. If you have another key, try using that one. Also, check your VIN number on safercar.gov to...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...