If you have a car or truck and think it may have low fuel pressure, several symptoms are caused by fuel delivery issues.
Symptoms include long start times, rough idle, check engine light on, misfire codes (P0300-P0308), engine running lean (P0171 Code), and reduced engine power.
Low fuel pressure is often described as the vehicle running out of gas.
Symptoms of Low Fuel Pressure
- Long Engine Start Times
- Engine Does Not Start
- Rough Idle
- Check Engine Light On
- Misfire (P0300-P0308) Codes
- Engine Running Lean (P0171 Code)
- Reduced Engine Power
Low fuel pressure will limit gas to the engine and cause long start times.
If you have to wait longer than normal for the engine to start, it may be not getting enough gas.
The engine may not start since it is not receiving enough fuel.
A fuel pressure gauge can be used to see if the engine is getting the correct amount of pressure to start.
A rough idling engine and stalling out are other symptoms of gas delivery issues.
The engine may have a rough idle since the fuel delivery is sporadic and not at a steady rate.
The engine light or a warning message will likely come on, and multiple codes will often be given.
The engine error codes can be read with an OBDII scan tool.
There are many low-cost scan tools available, and many automotive stores will do scans for free.
The cylinders need gas, air, and a spark correctly timed to run well.
If one of these is off, such as no gas, then a misfire will occur.
When the vehicle computer is scanned for error codes, a P0300-P0308 misfire error code will often be given.
When more air than gas goes into a cylinder, it causes a lean condition.
A lean condition points to a fuel delivery problem, such as low fuel pressure.
When scanned for errors, lean condition codes will be given, such as a P0171 Code.
With less gas available when needed, the engine will have less available than it normally would.
When pressing on the gas pedal, the vehicle may be slow to start and have no power.
Possible Causes of Low Fuel Pressure
- Faulty Fuel Pump
- Clogged Fuel Filter
- Bad Fuel Pressure Regulator
- Bad Fuel Rail Pressure Sensor
- Fuel Tank Contaminated
- Fuel Line leak or Clogged
A bad or failing fuel pump can cause low fuel pressure.
The fuel pressure can be tested with a pressure gauge to see if it is working correctly.
A clogged fuel filter is common with vehicles that have an inline filter.
Not all vehicles have an inline filter with many located with the fuel pump located in the gas tank.
If your vehicle does have an inline fuel filter it is a good idea to replace it since it is a part of regular maintenance and a common failure.
The fuel pressure regulator can cause issues if it becomes clogged up.
It is usually located on top of the engine but can also be located on the fuel pump, mainly with Chrysler or Dodge vehicles.
A bad fuel rail pressure sensor can also cause issues,
Usually, when a fuel rail pressure sensor goes bad, it will give another code, such as
If the gas is contaminated inside the gas tank, it can clog up components and block the flow of gas.
Often, contaminants will block the fuel filter and sometimes the fuel pump strainer.
If a fuel line has been damaged, it may be leaking fuel.
A clogged line will also cause issues and block gas.