Symptoms of a Clogged Fuel Filter

By | August 3, 2023

Symptoms of a Clogged Fuel Filter
If you have a vehicle and suspect it has a clogged fuel filter, there can be various symptoms.

The symptoms will vary depending on how clogged up the filter has become.

A clogged fuel filter will block the flow of gas to the engine, causing it to run badly or not at all.

What Happens When Fuel Filter is Clogged?

What Happens When Fuel Filter is Clogged

  • No Fuel to Engine
  • Low Fuel Pressure

The engine needs a set fuel pressure up to the fuel-rail to run properly.

If it does not have the correct PSI of pressure, it will have issues and either run badly or not at all.

Every engine has a set PSI of fuel pressure it needs to run before there is a problem.

The PSI output can be checked with a fuel pressure gauge to see if it is correct.

Symptoms of a Clogged Fuel Filter

Symptoms of a Clogged Fuel Filter (2)

  • Hard to Start or
  • No Start
  • Idling Rough
  • Bad engine performance

A clogged fuel filter is often described with the same symptoms as running out of gas.

The gas flow may be sightly blocked, allowing the engine to start but run rough and have bad performance.

A fully clogged filter will block all gas to the engine and cause it to not start.

In-line Fuel Filter vs. In-Tank Fuel Filter

In-line Fuel Filter vs. In-Tank Fuel Filter

  • An Inline Fuel Filter is on the fuel line between the engine and gas tank.
  • In Tank Fuel Filters are in the gas tank on the fuel pump.
  • There are two types of fuel filters: in-line and in-tank filters.

    An in-line filter will be on the gas line between the engine and the gas tank.

    An in-tank filter will be in the gas tank with the fuel pump.

    Causes Why a Fuel Filter Becomes Clogged

    Causes Why a Fuel Filter Becomes Clogged

    • High Mileage
    • Contaminants In Gas Tank Usually Rust
    • Fuel Filter Installed Wrong
    • Vehicle Has Been in Storage
    • Old Gas

    The main cause of a clogged fuel filter is it has high mileage and needs to be replaced.

    Fuel filters have a rated mileage before they need to be changed out.

    The mileage can vary, but they are usually replaced between 30,000 and 60,000 miles.

    If the filter is becoming clogged much sooner than the rated millage, then there is likely an issue.

    For example, if the filter lasts less than 10,000 miles, there is something that is clogging it up.

    Contaminants inside the gas tank can also quickly clog up a filter.

    The main contaminant is usually rust, but any particles or water in the gas tank will cause a problem.

    If the vehicle has been in storage or not started in a while, this can notoriously cause the gas tank to rust and clog up a filter.
    Bad Fuel
    A car or truck that has been in storage for 6-12 months or longer often has a rust issue.

    Often, the fuel pump will also burn out quickly with contaminants in the gas.

    An in-line fuel filter installed backward will also cause problems.

    There is usually an arrow for the direction in which it needs to be installed, with the arrow pointing toward the engine.

    Some in-line fuel filters will be marked Inlet and Outlet, with the inlet coming from the gas tank and the outlet going to the engine.

    Bob Thomas

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