SYMPTOMS OF A BAD FUEL FILTER
purpose
The purpose of the fuel filter is to prevent debris from getting into the fuel injectors.
LOCATION
The location of the fuel filter will be inside the gas tank or on the fuel line between the fuel pump and the fuel injectors.
A good rule of thumb is to replace the fuel filter every 50,000 - 100,000 miles. Manufacturers of some newer cars state that the fuel filter will last the life of the vehicle.
symptoms
engine light
The first symptom of a bad fuel filter is having an engine light on. Since the fuel filter isn’t electrical, it won’t throw off a specific code but you might get a P0171 code (lean condition), indicating there’s more air than fuel in the combustion process. A lean condition usually leads to misfires, so you might also get a P0300 code (random/multiple misfires).
Ensure you can access your car's diagnostic codes by acquiring an OBD2 scanner here.
crank but no start
The second symptom of a faulty fuel filter is a crank but no start. You’ll hear the starter turning but it won’t do anything since there isn’t enough fuel to combust and keep the engine going. This only happens if the fuel filter is extremely clogged.
rough idle
The third symptom of a bad fuel filter is a rough idle. While stationary with the car on, you’ll feel the car vibrating. For a car to run its best, it needs to be at the perfect air-to-fuel ratio (14.7 kg air per 1 kg gasoline). A clogged fuel filter restricts fuel from getting to the injectors at the time needed, disrupting this ratio. This is why you may experience a rough idle.
engine hesitation
The fourth symptom of a malfunctioned fuel filter is engine hesitation. You’ll press down on the gas pedal to increase speed but the car stutters before it moves. This happens due to the lack of fuel not being able to keep up with the demand of air coming into the engine. When the gas pedal is pressed down, the throttle plate opens up to bring in more air. When this happens, the ECM (Engine Control Module) commands more fuel. The problem is that a clogged fuel filter restricts the flow of fuel. This delays the time it takes to transfer fuel from the tank into the injectors.
engine stalling
The fifth symptom of a bad fuel filter is your engine stalling. Maybe you’ll be driving uphill and it turns off or you press the gas pedal down to increase speed and it results in the same thing. The reason why it stalls out is because the air-to-fuel ratio is too lean. If the fuel filter is clogged it’s going to restrict the amount of fuel needed, resulting in a stalling engine.
If you suspect a bad fuel filter try using a fuel pressure gauge before replacing it. A clogged fuel filter will result in low fuel pressure. You can get a fuel pressure gauge here.
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