Skip the auto shop - Our mechanics make house calls

How to Check the Choke on a Carbureted Engine

carburetor

The choke is a plate in the carburetor that opens and closes to allow more or less air into the engine. Similar to the throttle, the choke plate rotates from a horizontal to vertical position to open up the passageway and allow more air to get by. The choke is located before the throttle, and manages the total amount of air going into the engine.

The choke is only used when starting a cold engine. When doing a cold start, the choke should be closed to limit the amount of air going in. This increases the amount of fuel in the cylinder and helps to keep the engine running, while it is trying to warm up. Once the engine has warmed up, a temperature sensing spring slowly opens the choke plate to allow the engine to breath fully.

If you are having trouble getting the car started in the morning, inspect the choke on your engine. It may not be completely closed on cold start, allowing too much air into the cylinder, in turn preventing the car from idling correctly. Once the car has warmed up, if the choke does not open fully, the restriction in air may result in reduced power.

Part 1 of 1: Inspect the choke valve

Materials Needed

Step 1: Wait until morning to check the choke. Check the choke and see if it is closed when the engine is cold.

hand removing air filter

Step 2: Remove the air filter. Locate and remove the engine air filter and housing in order to access the carburetor.

This may require the use of hand tools, however, many times the air filter and housing are secured using only a wing nut that can often be removed without using any tools.

choke valve closed

Step 3: Check the choke valve. The choke valve will be the first butterfly valve you see when removing the air filter. This valve should be closed because the engine is cool.

Step 4: Step on the gas pedal a few times. Press the gas pedal a few times to close the valve.

If your car has a manual choke, have someone move the lever back and forth while you watch and see if the choke valve moves and closes.

checking plate movement

Step 5: Try moving the valve slightly with your fingers. If the valve refuses to open or close then it could be stuck shut somehow, either from dirt build up or due to an improperly functioning temperature sensing adjustor.

spraying carburetor clean

Step 6: Use carburetor cleaner. Spray some carburetor cleaner on the choke and then wipe it down with a rag to clean out dirt.

It is safe for the cleaner to go inside the engine so don’t worry about wiping every last bit of cleaner.

Once you close the choke, reinstall the air filter and housing onto the carburetor.

Step 7: Run the engine until it warms up. Turn on the ignition of your car. Once the engine is warm, you can remove the air filter and check whether the choke is open or closed. At this point, the choke should be open to allow the engine to breathe fully.

  • Warning: Never start or accelerate the engine with the air cleaner removed in case of a back fire.

When you inspect the choke, you also get a chance to look inside the carburetor. If it’s dirty, you might want to consider cleaning out the whole assembly to keep the engine running smooth.

If you are having trouble identifying the cause of your engine troubles, get a certified technician from YourMechanic to inspect your engine and determine the cause of the problem.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...
P2159 OBD-II Trouble Code: Vehicle Speed Sensor B Range/Performance
Diagnostic Trouble Code (DTC): P2159 P2159 code definition Vehicle Speed Sensor B Range/Performance...


Related questions

Q: Black smoke issuing from vehicle and burning oil.

Hello, There is a common problem with the PCV valve allowing oil to enter into the intake and burn oil on these cars. There is a modified PCV valve that has been made to prevent this from happening. I would...

Q: The car won't run for longer than 30 sec.

When the car will only run with the choke applied, this suggests there is a larger fuel delivery problem. Start by checking the fuel lines, filter, etc., to be sure they are all free of dirt or any kind...

Q: not starting in park

This is an indication of a failed transmission range selection switch. The information from this switch is used not only to indicate the driver's choice of gear selection for the transmission to be electronically controlled, but also is used to...