Why does the car fail to start when hot but starts after cooling down?
2 Answers
There are several specific reasons why a car may fail to start when hot but starts after cooling down: 1. Fuel injector leakage: While fuel injection is normal operation, leakage constitutes additional fuel supply. The more severe the injector leakage, the richer the air-fuel mixture becomes, making it difficult to start when hot. 2. Damaged carbon canister purge valve: During hot starts, fuel atomization is normally sufficient without additional vapor supply. If the carbon canister continues supplying vapor to the intake, it creates an overly rich mixture, leading to starting difficulties. 3. Fuel quality: After hot shutdown, the engine compartment remains quite warm. If the fuel is highly volatile, it can form excessive vapor pressure in the fuel rail. When this pressure exceeds the fuel system pressure, vapor lock occurs, causing the injectors to deliver overly lean fuel vapor, resulting in starting problems.
I'm an experienced driver and have encountered this issue several times in my younger days – the car won't start when the engine is hot but works fine after cooling down. When the engine heats up, expansion can cause some components to deform. For instance, the crankshaft position sensor is prone to failure at high temperatures, leading to loss of ignition signals. It could also be a problem with the fuel system, where fuel evaporation during hot conditions creates vapor lock, blocking the fuel lines, which resolves once cooled. The most dangerous scenario is breaking down on the road, so don't delay. First, check if the spark plugs are worn out or have carbon buildup causing ignition failure at high temperatures, then inspect whether the fuel filter is clogged. If you're unsure what to do, drive to a professional repair shop immediately for diagnostics – safety first. Regular engine maintenance is crucial to prevent such heat-related failures and avoid unnecessary delays.
