What Causes the Engine to Stall When the Choke is Opened?
2 Answers
The engine stalling when the choke is opened may be due to issues with carburetor adjustment, where the fuel-to-air ratio is severely imbalanced, leading to insufficient combustion and stalling due to excessive air and insufficient fuel. Choke Construction: There are two types of choke constructions. One is the automatic electric choke, and the other is the manual choke. The manual choke is more intuitive and stable in control, requiring no adjustments. The driver simply feels the length of the cable pulled to adjust the mixture concentration. Choke Function: During cold starts, the choke appropriately closes part of the air intake to increase the gasoline concentration in the mixture entering the cylinder, improving the engine's starting performance. Once the engine is running normally, the choke should be fully opened. Otherwise, an overly rich mixture can cause the engine to malfunction and result in excessive fuel consumption. Fuel-injected engines automatically control this process without manual operation.
The engine stalls as soon as the throttle is opened. I've encountered this issue several times at the repair shop. A common cause is excessive carbon buildup in the throttle body, which obstructs air intake and prevents the engine from getting enough air. It could also be a faulty mass airflow sensor or a vacuum leak in the hoses, which disrupts the air-fuel mixture ratio. When the throttle is opened, the engine draws in too much air without sufficient fuel, causing it to stall immediately. A malfunctioning idle control valve can also get stuck when the throttle is opened, leading to a sudden drop in RPM. I usually start by checking if the air filter and throttle body are dirty—cleaning them often solves the problem. If that doesn’t work, I use diagnostic tools to check sensor data. Throttle-related stalling is annoying and dangerous, especially when starting, so I always recommend avoiding DIY fixes and seeking professional repair shops instead. Regular engine maintenance can help prevent this issue.
