Why might a car not start then start the next day?

Answer 1

Reasons why a car might not start one day but does the next:

• It could have been flooded with gas (although this is less common in newer cars).
• The gas line could have been frozen the first day and thawed by the next.
• Cold weather can also cause the fluids in the engine to thicken, making the engine unable to "crank" fast enough to start.
• The battery could be a little low from cold weather or approaching end of life, and not provide enough power to "crank" the engine.
• It could be a diesel engine in cold weather.*
• There might be dirt or other debris in the gas plugging the line that gets unplugged the next time the engine is started. Use better gas (e.g. brand name). Check fuel filter.
• A starter wire could have a loose connection that causes intermittent starting problems.
• A spark plug could be malfunctioning or dirty.
• If it happens when the engine is hot, it could be the ignition module.
• Might be a loose starter motor control wire.
• You may be at the bottom of the fuel tank and not know it because you have a faulty fuel gauge, then you could have the debris in the gas problem when you don't expect it.
• Your air control valve may be dirty.
• Fuel pressure could be an issue.
• Battery contacts could be dirty or loose.
• The alternator or distributor may need maintenance.
• There might be a problem with the anti-theft system, disabling starts. Or with a programmed key that the car no longer recognizes.
• It could be the computer has loose connections or has gone bonkers.
• If you have driven through water, washed the engine, or otherwise got water in the ignition, it could be short circuited by water that evaporates by the next day.

As you can see, there are many things that could be wrong, this is not an entire list by any means. However, the most common problems are with ignition, battery, fuel delivery, dirty parts, and bad wire connections.

*If the temperature is cold, diesels are notoriously hard to start. As mentioned above, in cold weather oils in the car thicken and battery strength drops, both making the engine hard to crank. The type of oil may need to be changed. Thicker oils like 15W-40 are great in warmer weather in diesels, but when temperatures get below freezing or even lower, they get too thick. 30 or 40 weight oils are especially too thick. Or you may need to use an engine warmer to keep the oil from getting thick in winters.