You car’s fuel filter does exactly what it’s name implies. It works as a middle man, filtering out any impurities in the fuel sent from your gas pump to your fuel injectors. When a vehicle’s inline fuel filter is working properly, your engine gets a healthy injection of proper fuel without any foreign body and your car runs smoothly.

While fuel filter problems may start from a range of places—including an old and dirty fuel tank, clogged fuel line, cheap filter element, and a dirty fuel —the signs that manifest on the outside may not obviously suggest any of those causes.

Here are some warning signs that a fuel filter requires replacement.

1. Engine Won’t Start

A really dirty fuel filter may stop your car from starting at all. Fuel pressure, mostly in normally aspirated vehicles, cannot overcome the clogged fuel filter. The meaning here is that despite your fuel’s pressure trying to push things forward through the engine, the gasoline itself is just too heavy contaminants that failed to be filtered out. When the engine is cranking normally but won’t start, check the fuel filter.

2. Engine Idles Roughly

When stopped, your tachometer might display erratic readings for your engine speed. A normal idle RPM (revolutions per minute) of a car is between 400-800 RPM. If it falls below that, again while idling, your fuel filter might need to be changed.

3. Engine Hesitates During High-load

If you are overtaking another car or driving uphill and the engine hesitates, this is an indication of a clogged filter. In situations like these where you need a sudden burst of power or acceleration, your car’s lack of responsiveness can be dangerous and downright scary.

One reason this can likely be traced back to an inline fuel filter issue is because each time you step on the gas pedal, you require your engine to demand much amounts of fuel to accelerate. When the fuel delivery system is blogged or the fuel being injected into the engine isn’t as pure or potent due to poor filtration, those same time of acceleration attempt to occur without enough fuel to actually make them happen.

4. Start-Stop Engine Problem

An engine that goes dead frequently while being driven could be a sign of a dirty fuel filter. Your car may start normally but with a noticeable loss of power when driven. The more often you stall like this, the smaller the amount of gas your engine is receiving, likely due to severe clogs in your filter.