What Causes a Car to Fail to Start on Rainy Days?

[LeLevi]

The reasons why a car fails to start on rainy days are as follows: 1. Short circuit: Since most of the vehicle's wiring and pipelines are concentrated in the engine compartment, driving through water can inevitably splash water onto the internal wiring and pipelines. Over time, this can easily lead to electrical short circuits and obstructed fuel lines, with the most direct fault being the car's failure to start. 2. Battery: In low temperatures, the 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, preventing it from reaching the minimum starting speed and 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 dense mixture, it becomes difficult to ignite the mixture, leading to engine starting difficulties.

[StEverly]

I've seen many car owners unable to start their vehicles on rainy days, mostly due to damp air filters or ignition systems. Rainwater can easily seep under the hood, especially in older cars with larger gaps, soaking the air filter and affecting engine air intake. If the ignition wires or spark plugs get wet, the electrical spark won't ignite, naturally preventing the car from starting. I recommend regularly checking the engine compartment's sealing strips and covering the car before rain. Battery terminals may also oxidize, with rainwater and oxidation causing poor connections and insufficient power supply. If the car won't start in the rain, wait a few minutes for moisture to evaporate before trying again. If it still doesn't start, it's best to call a tow truck for a professional check of the electrical system. Safety first—don't push your luck and delay necessary repairs.

[McJohn]

I reckon this issue might be due to moisture in the battery or connection problems. Rainwater causes oxidation on battery terminals, leading to poor contact and disrupted current flow. The same thing happened to my car last time – it wouldn't start after rain, and when I opened it up, the terminals had turned green. Wet high-voltage wires or ignition coils can also cause short circuits. Try DIY troubleshooting: pop the hood, check for corrosion on battery terminals, and clean them with sandpaper. Replace the air filter if it's wet. Don't forget about fuses – they're prone to blowing in damp conditions. If all else fails, try jump-starting. Park in dry spots regularly and maintain your battery to prevent this.

[AliceMarie]

I think that cars not starting on rainy days is often related to damp electronic components. If the spark plugs or distributor get wet and short-circuit, the engine won't ignite. A wet air system can affect the combustion of the air-fuel mixture. It's best to park the car indoors or cover it. In case of sudden occurrence, check for loose wiring and remain patient.