What Causes Difficulty in Starting a Hot Engine?
2 Answers
After the engine has been turned off for a while, the temperature in the engine compartment remains high. Fuel is prone to evaporation under such conditions, which can lead to high vapor pressure in the fuel rail. When this pressure exceeds the fuel supply system's pressure, vapor lock occurs, causing the fuel injector to spray an overly lean mixture of fuel vapor, making it difficult to start. The details are as follows: 1. The fuel injector normally sprays fuel, but if it leaks, it provides extra fuel. The more severe the injector leakage, the richer the air-fuel mixture becomes, leading to difficulty in starting a hot engine. 2. It could also be due to a faulty carbon canister purge valve. During a hot start, fuel atomization is already normal, and no additional fuel vapor is needed. If the carbon canister continues to supply fuel vapor to the intake manifold, the air-fuel mixture becomes too rich, resulting in difficulty starting.
There are many reasons why a hot car won't start. Common issues include problems with the ignition system, where spark plugs are prone to aging or carbon buildup affecting ignition under high temperatures. The fuel system may also malfunction, with the fuel pump's efficiency decreasing when heated or nozzles becoming clogged, leading to insufficient fuel supply. Another common factor is engine overheating, which can cause component expansion affecting the compression ratio or sensors falsely reporting temperature. Batteries and starters are also prone to problems under high temperatures, such as loose connections or unstable voltage. I've encountered this situation where it's difficult to restart after parking, especially in summer. It's recommended to check the spark plugs and fuel pump, clean the throttle promptly for prevention, and maintaining a normal cooling system can significantly reduce the risk.
