fuel pump

Symptoms of Low Fuel Pressure & The Causes

In Engine by Magnus Sellén10 Comments

fuel pumpA vehicle requires proper fuel delivery to its engine to function properly.

There are at least 4 components that make up a vehicle’s fuel system which includes the fuel pump, fuel pressure sensor, the fuel rail and the ECU which monitors everything.

The fuel pump receives the fuel from the fuel tank and throws it into the fuel rail which transfers the liquid into the cylinders using the knowledge of the fuel pressure sensors.

Naturally, if the pressure is not according to the manufacturer’s recommendations, you will experience little to no response from the car’s engine.

In this article, we will discuss the various symptoms that arise from low fuel pressure or a failing fuel pump.

Signs of Low Fuel Pressure

First, you will see a chart of the possible causes, solutions, and symptoms of low fuel pressure. If you want more detailed information go down in the article to get the information you need.

1. Unresponsive Throttle

All cars require proper fuel delivery to their cylinders in order for them to run properly. If you feel any lags in your car’s pickup there is definitely a problem with your fuel system. A clogged fuel pump can be the biggest cause in such a case.

2. Difficulty Starting the Car

Low fuel pressure will also make it hard for you to ignite your car’s engine. You might feel it takes longer to start your car or maybe more than one tries to make a successful ignition. Other than that, you might feel some backfire from your engine.

3. Stalling Engine

If your car’s engine stalls while running, it is a clear sign you are having some problems with your fuel pump. This is possible because the engine is not receiving the correct amount of fuel to maintain combustion.

4. Engine Tuning

While engine tuning is not affected immediately, in the long run, you would feel a change in your engine’s tuning. Any such effect should tell you that there are irregularities in your fuel pump or fuel injection.

5. Check Engine Light Comes to Life

Today’s electronic cars have a fuel pressure sensor that intelligently calculates if anything is going wrong. If it is, the sensor triggers the check engine light prompting you to get your fuel system checked. Generally, with such a problem you will get a P0190 code accompanying your problem. If the Check engine light occurs, you should read the trouble codes with a diagnostic scanner to find out what the problem is.

6. Black Smoke from Exhaust

Gasoline run cars are usually not a huge threat to the environment as they do not emit harmful chemicals from their exhaust. However, if your car starts to excrete thick black smoke from the exhaust after you start it, there is definitely something wrong with the pressure in your fuel system. But in this case, rather high fuel pressure.

7. Turbo Lag

A lot of people might not have turbos in their car but those who do have another way of knowing if there’s something wrong with their fuel pressure. The turbo system uses air and heats it up to create a turbine like an effect on the engine allowing it to create more power. However, if you feel your turbo is taking too long to spool, there might be something wrong with your fuel pump and pressure.

8. Spark Plugs / Misfires

A low-pressure fuel system will destroy the spark plugs that ignite the fuel in an engine’s cylinder. If by chance you are replacing them and you find they are worn out before their time, you might be looking at a problem with your fuel system.

Fortunately, the fuel system in a car requires only needs minor tweaks. Sometimes the problem is very minor and at times it can be huge.

Low fuel pressureMisfires

Check Engine Light

Low acceleration

Rough idle

Unresponsive throttle

Stalling engine

Faulty Fuel Pump

Clogged fuel filter

Clogged fuel lines

Faulty fuel pressure regulator

Wirings to fuel pump
Repair wirings to fuel pump

Replace fuel pump relay

Replace fuel pump

Replace fuel filter

Replace fuel pressure regulator

Replace/Clean fuel lines

How to fix a Low Fuel Pressure Issue

There are a lot of different causes of low fuel pressure, but here you will find the most common solutions to fix your low fuel pressure.

Change Screen Filter

The first thing you can do is to check the screen filter. The screen filter protects the fuel pump from dust and debris and can get clogged up pretty quickly. This can hinder the flow of fuel to the fuel pump and into the cylinders. So, it is better to clean the screen filter, replace it with a new one if needed. This slight adjustment will change the entire feel of your ride.

Check Voltage

The fuel pump is able to create pressure using electricity but if it is not getting the adequate voltage of electricity it will not be able to function properly. Consequently, the fuel will not be released at the perfect pressure and your car will lose efficiency. Although, voltage fluctuation in a car is rare it is not uncommon. This problem can be solved by checking the battery and the wires transferring electricity. You can check the voltage with a Multimeter (Link to Amazon).

Replace the Fuel Pressure Regulator

The regulator controls the amount of fuel that leaves the fuel pump. If this small component fails, the fuel rail will not receive the correct amount of fuel and thus the engine will not be able to run at peak performance.

Change the Fuel Filter

Gasoline or diesel comes from the ground and no matter how much they are purified some pollutants can pass through and reach your car’s fuel tank. That’s why mechanics use a simple solution. A fuel filter. A fuel filter cleans the fuel from any remaining pollutants and makes it pure enough for the engine. Fuel filters are generally very cheap an easy to replace, such that you don’t need a mechanic to replace one for you.

Fill the Tank

Sometimes, the fuel pressure cannot be maintained because there is inadequate fuel being received from the tank. Therefore, if you feel any of the above symptoms first check if you have adequate fuel in your tank and then proceed to diagnose the problem.

Repairing the Fuel System

As mentioned before, the fuel system consists of quite a few components, which means it is not easy to replace all of them. However, the important ones like the fuel pump and the fuel filter are easily replaced and generally do not cost too much.

Having said that, it depends on the make and model of your vehicle before any decision about the price can be made. For instance, the fuel pump for a 2004 Range Rover can cost $914, while a 2004 Chevy Silverado’s fuel pump can cost $414.

These prices exclude labour costs, meaning you are in for a hell of a ride if your fuel pump ever goes awry. Fortunately, there are cheaper dealerships that can do the same work for half the money. From them, you can expect your work to cost anywhere between $150 – $350

Hello I'm Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I'm specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I'm here to give you answers to all your automotive questions and I hope that you enjoy our content.

  1. Toyota Tacoma rough idle black smoke when it warms up. New plugs,wires,fuel filter. Coil packs,egr valve,poor fuel mileage. Is this a fuel pressure problem?

    1. Author

      It could be, But check for any intake leaks.

      Also check the trouble codes in the engine control unit with an OBD2 scanner, which might give you an idea of the fault 🙂

      1. i still have an code for the fuel pressure sensor after replacing sensor.and replacing cam follower in fuel pump on a vw golf mk5 1.6
        Would it be an blocked fuel filter or ???

  2. i nave this vw 2007 passat 2.0T that vehicle has been to serval repair shop spend a lot $$$ on this vehicle wich code are p088A that come for low fuel pressure shoul i replece fuel pump even the car run ok

    1. Author

      First, make sure that the fuel pressure sensor is correct. Check the fuel pressure with a manual fuel pressure gauge to figure out if you can find any problems with the pressure. If so check fuel pressure regulator. Could also be a faulty fuel injector which is injecting too much fuel which is causing the pressure to get too low, but the car would smoke a lot. It could, of course, be the fuel pump or the fuel filter also. A real diagnostic troubleshooting is required here!

  3. I’ve had this faithful rig since 2007. Never had it left me stranded or confused. It is now in its 3rd mechanic shop leaving them all scratching their heads. December 2018 I took it to get a Christmas tree, it started up and ran as usual but then about half way to my destination it acted as though it was struggling for fuel. Very chuggy rough driving. I got to my destination shut it down, went and cut our tree. Started it back up, it idled ok so I continued down the hill. Once I got on the highway I really had to apply the gas, this was only about 5 miles from home. I got home, parked it, a few days later I had it towed to the first mechanic shop. He told me I had melted my catalytic converters. I had him replace them. He had it in his shop for about a month. He changed, also, the TPS. He returned my car and said it’s still a little hesitant but should be good to drive and suggested that I change the MAF. I did that. No change! Off to the second mechanic, full diagnosis, the first mechanic never replaced the O2 sensors so they were replaced, this mechanic said my MAF was reading high and low voltages, he also found that my check engine light was now disconnected? After about 2 months he returned my car and said try a new ECM. Easy plug n play so I replaced it. Nooooooo change. It’s now been towed to the third mechanic. They found 55# pressure at the fuel pump but significantly dropped to 34# at the regulator. They’ve had it for about 3 months and are also scratching their heads but don’t want to give up. Any ideas are much appreciated. Outside of taking it to a dealership. Sorry for the long thread

  4. My motorhome ran fantastic for about 10 miles. Then, when I tried to accelerate, I lost power and could only get to 30 mph before it would backfire, spit and sputter. It turned out to be the person who changed the filter damage the fuel line with a small leak. Couldn’t see fuel on the ground, but it caused less fuel getting to injectors causing my issues. Replaced fuel line.

  5. hi. i own a 2006 impreza wagon r, 2.0l non turbo. i had a p0328 error code, which led me into changing the knock sensor. however after the new sensor was installed the same code appeared and the engine behavior hasn’t changed. I thought the code might be due to poor fuel pressure making the engine to really knock. any thoughts on this? thanks

  6. Low pressure in fuel rail, had 4 injectors in. 1.6 tdi 72’000 miles Glow plug light flashes he’s goes into limp mode

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