What Causes a Car Not to Start on Rainy Days?

[LeDonovan]

The reasons a car may not start on rainy days are short circuits and battery issues. Specific details are as follows: Short Circuit: Since most of the vehicle's wiring and pipelines are concentrated in the engine compartment, driving through water may cause internal wiring and pipelines to get splashed with water. Over time, this can easily lead to electrical short circuits and fuel line blockages, with the most direct symptom being the car failing to start. Battery: In low temperatures, a car battery's electrolyte viscosity increases, reducing its permeability and increasing resistance, which lowers the output power. This makes it difficult for the starter to crank the engine to the minimum starting speed, affecting engine ignition. Additionally, the low terminal voltage of the battery results in weak sparks from the spark plugs. Combined with the increased resistance between electrodes due to the denser air-fuel mixture, it becomes difficult to ignite the mixture, leading to engine starting difficulties.