Low Fuel Pressure (Causes, Solutions & Fixes)

low fuel pressure

All vehicles must have a designated amount of fuel delivery to the cylinders for the engine to run properly. Low fuel pressure can inhibit the proper flow of fuel to the engine.

Read on to find out how to diagnose low fuel pressure as well as how to fix the problem.

What is Low Fuel Pressure?

The appropriate fuel delivery from the gas tank to the fuel injectors must flow at the correct pressure and rates for the engine to operate. Older vehicles had a fuel pump which sent too much fuel to the engine. The pressure regulator mounted on the engine.

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Your car has a designated delivery of fuel to operate as designed. The designated pressure is from the manufacturer recommendation. When the fuel delivery is off, it means the engine will not function properly.

The fuel system consists of a fuel pump (view on Amazon), fuel pump sensor, an engine control unit (ECU), and fuel rail (view on Amazon).

Fuel Pump -The fuel pump is designed to pump fuel from the gas tank into the engine. The pump is the modern method for supplying the carburetor with fuel. As the fuel system design of the automobile has improved, the fuel pump design also has progressed to more methodical.

Engine control unit (ECU) – The ECU monitors the activities that occur within the fuel system. When something goes off track, the ECU can report the event for the OBD2 system.

Fuel Rail – The fuel rail transfers the fuel to the cylinders according to information from the fuel pressure sensors.

Causes of Low Fuel Pressure

Several factors can contribute to low fuel pressure as the fuel system is complex with delicate tasks that must but accurate and consistent. When something goes wrong, it affects your engine performance and in extreme cases, it shuts your engine down. Here are the most common causes of low fuel pressure:

Clogged fuel pump – This is a very common cause of low fuel pressure. Diagnosing problems in your fuel system begins with identifying the type of fuel pump you have. In many newer cars, the fuel pump is located inside the gas tank. The fuel system in your car is critical to your engine performance. The fuel pump transfers the gas from the tank to the engine. Fuel pumps are supposed to only pump fuel to the carburetor when it is needed;. Yet, the pump must be able to deliver the fuel at constant pressure.

Dirty fuel filter – A fuel filter is located on the fuel pump discharge side. The fuel filter should block most debris and contaminants from entering the fuel system. When the filter becomes clogged, the materials reach the fuel system and affect the fuel flow.

Failing fuel pump – A failing or bad fuel pump is a major cause of low fuel pressure. The gear rotor fuel pump can have so many internal components. The gears in the fuel pump can wear out naturally over time, or there may be an electrical problem, dirt, or rust in the gas tank that causes the fuel pump to go bad.

Restricted fuel lines –

Clogged pump inlet strainer– While there is a fuel filter on the discharge side of the fuel pump, there is a strainer on the suction side of the pump. The strainer O-Ring seal may fail which results in leaks.

Bad fuel pressure regulator – The fuel pressure regulator keeps a check on the fuel pressure as it flows through the fuel system. The regulator ensures that the fuel injectors receive the right amount of fuel by building up the pressure in the fuel rails. When the regulator fails, the fuel distributions are not balanced. This hinders or shuts down the engine performance.

Not enough voltage – The fuel pump may be failing to operate properly because there is not enough voltage from the supply circuit to fully operate the pump. Your battery may be low or some other obstruction could be restricting the amount of electricity goes to the fuel pump.

Bad fuel lines -Pressure is also a big issue in the fuel lines. The right amount is needed to make sure the fuel injectors receive the right amount of fuel. When the lines are restricted or leak, the pressure is reduced.

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Signs of Low Fuel Pressure

Low fuel pressure is a serious problem that can cause your engine and fuel system to act out in inappropriate ways. Your car needs clean fuel traveling to the engine in the right amount. When this is not happening, your car will show signs that there is a problem. Here are the most common signs of low fuel pressure.

Check Engine Light – The Check Engine Light (CEL) on your dash will activate to let you know something is wrong under the hood.

OBD2 Code P0190 – If you use an OBD2 scanner to pinpoint problems with your car, you may get a P0190 “Fuel Rail Pressure Sensor Circuit Malfunction” diagnostic trouble code (DTC). This code means that the power control module (PCM) has found the fuel rail sensor if not set within the required range. There could be problems with the fuel rail pressure sensor, the fuel pump, the fuel filter, vacuum leaks, or the electric wiring or connectors within the fuel system. The check engine light may come on along with the trouble code.

Unresponsive Throttle – When there is a delay in trying to start your car, the fuel system has a problem. The unresponsiveness is referred to as a cold throttle. This problem may require replacing the fuel pressure regulator or the fuel pump.

Engine Stall – An engine stall means your engine is not receiving an adequate amount of fuel, which is a sign of low fuel pressure. There is not enough fuel to complete the combustion process. You may be able to correct this by cleaning the fuel lines.

Engine Won’t Start – You may hear the spark plugs firing when you turn the ignition but the engine won’t turn over. The fuel pump becomes pressurized when you turn the key in the ignition. As the fuel pump continues to wear down, eventually it fails all together. In the beginning, you may have a tough time starting your engine up, taking many more cranks to get going. In the more advanced stages of fuel pump failure, the engine may not start at all. Fuel is no longer reaching the engine when you turn the ignition.

Smoke from the Exhaust – Low fuel pressure or high fuel pressure can cause black smoke to come out of the exhaust. Smoke coming out of the exhaust, or tailpipe can be several colors, including, blue, grey, white, or black. Thick, black smoke likely means that the engine is being flooded with gas or a fuel line is being obstructed. The darker the smoke coming from the exhaust, the higher the need to find the problem and fix it.

Engine Tune – Low fuel pressure can wear your engine’s performance over time, which means you will need a tune up. Your car may have problems starting up as the low fuel pressure makes it difficult for inside the engine to ignite. There is not enough gas to achieve combustion.

Misfiring/Spark Plugs – The spark plugs ignite the fuel and air mixture in the combustion chamber. When the plugs are dirty or damaged, the mixture is not regularly lit. The spark plugs are no longer useful. This causes your engine to sputter and misfire. When you are driving at higher speeds, you can feel the engine hesitate and then resume. This means the fuel pump is not providing fuel to the engine consistently. The engine is getting some fuel, but the delivery is not sufficient.

How to Fix Low Fuel Pressure

If your car has low fuel pressure problems, it’s best not to drive it until you can have it repaired. Whether you are a mechanical genius or you still don’t even have a clue what low fuel pressure is, it needs to be addressed right away. Here are some of the first things you can do to help the problem before the engine becomes damaged:

Check the Voltage – You can test the voltage to make sure there is enough power to operate the fuel pump. The wires that connect to the fuel pump may be damaged and need to be replaced.

Check the OBD2 codes – When components in your fuel system go bad, the computer in your car makes a record of each event. You can use an OBD2 Scanner (view on Amazon) to check the trouble codes that have been thrown about your vehicle. We’ve already covered the P0190 trouble code. Another code that you may get is the P0087 “Fuel Rail/System Pressure – Too Low” DTC. This code confirms the low fuel pressure and most likely it will trigger the engine check light.

Get Some Gas – The internal combustion engine must have fuel to function. If you have been driving with the gas needle on “E”, sooner or later, the engine will stop working, as the internal combustion process is incomplete. However, if your gas tank is full of fuel and your car is sputtering, there is a different type of problem.

Change the Screen Filter – Materials that corrode or contaminate in the gas tank can end up in the fuel pump. You may think the fuel filter is keeping things clean, only to find that this not the case. The inlet screen may stop some debris from entering the fuel pump, but it will not catch all of it.. You must change the filter. This is a cheap, expediate way

Replace Fuel Pressure Regulator – The regulator controls the amount of fuel that flows out of the fuel pump. When the regulator goes bad, the fuel rail does not receive the right amount of fuel.

Replace the Fuel Filter – Even using premium gasoline won’t stop contaminants and debris from entering your fuel system. When the fuel filter is not doing the job, these contaminants or debris can enter the engine. You may have to replace the fuel filter to make sure the fuel that goes to the engine is clean..

Get Help from Certified ProfessionalsThe automobile can become a burden in in regard to fuel and maintenance. Many problems associated with the fuel system cannot be solved at home. Keep your vehicle on the road for the long run by seeking a certified professional to help get rid of that low fuel pressure.

Be Safe

Driving a car with fuel system problems, such as low fuel pressor, can really cause damage to your engine in ways that you cannot come back from. It is also risky to drive in that condition as your engine may fail at any time. Be safe, get that low pressure problem fixed and drive safe.

Job Guthiri is a freelance writer with 3 years of experience writing for Motorsrun and other established automobile outlets. His focus and key interests are Tacomas and maintenance. Read our Editorial Guidlines and Fact Checking process.