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What causes my car to not start after getting gas?
While there are lots of reasons why a car might not start, only one reason is related directly to fueling up your car.
Bad EVAP Purge Control Valve
This valve is designed to help purge the air out of your gas tank to keep the gas flowing. The valve can get stuck open and cause fuel to flow directly into your intake manifold. The intake manifold is meant for air, so trying to start your vehicle with an excess of fuel in the chamber will actually make it more difficult to start because it needs a mix of fuel and air.
For your information, you probably didn't do anything to cause this. Some parts just wear out. This problem is also a little more difficult to detect because most people don't know the valve exists, and there are other, more obvious places to look to see why your car isn't starting.
Reasons your car isn't starting
The rest of our reasons have less to do with fueling, and more to do with maintenance issues and turning off vehicles. Getting gas may very well have nothing to do with your vehicle not starting up again – the timing may very well be a coincidence!
A dead battery is a rather common and honestly totally preventable problem in most scenarios. If you recently replaced your battery – even within the last couple of years, it can also be an indicator of another mechanical issue in your vehicle. A dead battery normally gives you no lights on the dashboard and no signs of life within the vehicle, potentially including slow electronics and dim exterior lights.
The best way to prevent a dead battery is to maintain the battery and have it checked when you bring your vehicle in for maintenance. A dealership, shop, or just a battery tested in your own garage can readily tell you how your battery is feeling.
Your alternator is a unique part of your engine that transfers gas power to a charging battery. If your alternator goes bad, your battery will not recharge as it needs to. The challenge here is that your alternator doesn't always communicate its impending failure to your vehicle via dashboard lights. With a bad alternator, your battery might not be completely dead – it just can't receive more charge because the alternator is no longer capable of providing.
Bad fuel filter
Just like your cabin air filter and oil filter, you have a filter that keeps contaminants out of your fuel so that your vehicle performs well. If this starts getting clogged, you'll notice fuel efficiency dropping and performance going downhill. If the filter gets completely blocked, there won't be any fuel flowing to the engine.
The fuel pump is in the gas tank and has hoses that allow it to force fuel into the engine. Aside from overall wear and tear, letting your gas tank run too low too often can also cause distress for the fuel pump. You might start to hear whining sounds and diminishing performance as the fuel pump fails, especially when trying to accelerate.
The starter motor activates the engine when you turn the key. If this fails, your vehicle won't start. A starter failure can be indicated by a clicking sound when you try to start the engine.
Bad spark plugs should be obvious before a problem bad enough to stop the engine occurs, but it does happen! Spark plugs burn the fuel and air mixture, and are pretty important to starting the vehicle and running the engine. These do need occasional replacement and are also hopefully replaced before they become a major concern.
Key FOB problems
So this is more of a best-case scenario problem to have. When a key FOB is dying, it might not have the ability to get through the vehicle's security system. There is often a way around key FOB problems though – and it often involves pushing a push start button with the FOB itself. Otherwise, head into the gas station and see if they carry the watch batteries that key FOBs often use – this could be a very easy fix, especially if your vehicle has been warning you about a dying FOB.
Could the gas be bad?
This problem is pretty rare, and would most likely come from gas that has been exposed to contaminants like water before arriving at the station.
Bad gas is unlikely to be the single cause of your vehicle not starting unless you repeatedly visit stations that offer old gas. Then it is possible that the old or contaminated gas has gummed up your engine, leading to permanent damage.
Your vehicle will instead exhibit different symptoms, like a poor idle, stalling, or knocking noises – but the key will probably start the engine still.
What should I do when my car won't start after fueling?
One of the first things you'll want to do is check your battery. There is an odd chance that your battery cable become disconnected since you last started and stopped the car. This is honestly fairly unlikely – but it's also one of the easiest and free fixes available.
If your battery cable isn't disconnected, see if you can move the vehicle away from the pump. Getting the vehicle someplace else makes it more convenient for the gas station – and for you, and potentially a tow truck.
You should try to just start the car again to see if the first effort was a fluke. If not, consider calling a tow truck to either bring it to a mechanic or take it to your garage for further inspection.
About The Author
I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.Read More About Charles Redding