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What Is a Fuel Pressure Sensor, and What Does It Do?
The fuel pressure sensor is also referred to as the fuel rail pressure sensor, and shouldn’t be confused with the fuel tank pressure sensor which is located in a completely different part of the car. As the full name of this sensor implies, the fuel pressure sensor is located in the fuel rail and monitors the fuel pressure within the rail.
Along with the data received from airflow sensors, throttle position sensors, and the various other sensors within the fuel management system, the ECU (engine control unit) uses the data it gets from the fuel pressure sensor to make adjustments to the amount of fuel being sent to the cylinders and the ignition timing.
It’s important that your ECU receives the right data because it helps your engine run as smoothly and efficiently as possible while also producing sufficient power. If the fuel pressure sensor fails, it can throw off the accuracy of the entire fuel management system.
Cost of Replacement for Fuel Rail Pressure Sensor
Replacement of fuel rail pressure sensors is a costly affair. Depending upon the make and model of your car, it will cost you somewhere between $250 and $450. The breakdown of this figure will be:
· Fuel Rail Pressure Sensor Cost: $100 to $200
· Labor Cost: $150 to $250
Since the fuel rail pressure sensor is located deep inside the engine, many parts need to be removed to access it. This is the main reason why labor rates for replacement are so high.
For mass-produced and economy sector cars, you might be able to find spare parts at significantly lower prices. Luxury cars will cost you more.
Similarly, the mechanic shop doing the replacement will matter a lot in this situation. Dealerships tend to charge more than local workshops. The price difference is due to their highly skilled labor professionals specializing in dealing with all issues of that particular car or brand only.
How to Replace Your Cars Fuel Pressure Sensor
First off, we should mention that unless you have the proper tools and experience to complete a repair like this, you should probably just let a professional take care of it. Replacing a bad fuel pressure sensor isn’t the hardest repair to make, but if you don’t know what you’re doing then you might end up making it a lot harder than it needs to be.
Assuming you do have the necessary skills and equipment to handle a repair like this, however, here’s what you need to do:
- Disconnect the negative cable from your battery. Since you’ll be working on your car’s electronics, you should do this to avoid accidentally electrocuting yourself.
- Remove the plastic cover from your engine, if there is one. Depending on the layout of your engine, you may have to remove your air intake to gain access to the fuel rail and sensor.
- When you’ve found your fuel rail, locate the test port on it. Put a drip pan under the test port, and open the test port’s valve with a small screwdriver to depressurize the fuel rail.
- Disconnect the electrical harness and the mounting hardware from the fuel pressure sensor, and remove it from the fuel rail.
- Clean the fuel rail and the sensor’s electrical harness before installing the new sensor.
- Install the new sensor onto the fuel rail, making sure to fully tighten the mounting hardware.
- Reconnect the electrical harness to the new sensor. If you had to remove the air intake to access the fuel rail, you can reattach it now.
- Replace the engine cover, and reconnect the negative cable to your battery. If you did everything correctly, you should now be good to go!
Technical Characteristics Of A Fuel Rail Pressure Sensor
The supply voltage is – 5 ± 0.25, the temperature range is – 40° C to +130° C or -40° F to +266° F. Also, the measuring range is 0 bar to 1800 bar, and the response time is 2ms.
Fuel Pressure Sensor Location
The fuel rail pressure sensor is located at the fuel rail, which is located near the intake manifold.
In some car models, the fuel rail pressure sensor can also be installed on the fuel line, but this is pretty rare.
Check somewhere under the intake manifold, and I’m sure that you will find the injectors, fuel rail, and the fuel rail pressure sensor.
How Does the Fuel Rail Pressure Sensor Work?
Like any other sensor, the fuel rail pressure sensor has the sensing element and the calibrated unit. The sensing element is usually a tiny dome-shaped diaphragm or bellow that elongates when pressurized fuel passes through it.
This elastic or mechanical sensing part is calibrated against a voltage-producing element. This element generates a voltage corresponding to the elongation in the sensing element. This energy is then amplified in the same ratio to make the voltage detectable.
A signal is generated and sent to the Electronic Control Unit (ECU) of the car, which regulates the amount of fuel injected into the combustion chamber accordingly.
Delivering the right amount of fuel is essential as it directly affects the engine’s performance.
The combustion process involves an air-fuel mixture. The ratio of both constituents in this mixture is referred to as AFR (air-fuel ratio). The AFR governs whether the engine is running rich or lean. If AFR is greater than one, more air is in the ratio than fuel, aka the engine is running lean.
The fuel rail pressure sensor sends the signal to the ECU in the form of voltage to adjust the AFR. For normal performance, the AFR of the engine is set at 14.7:1. To increase engine performance, the amount of fuel is increased.
When the fuel rail pressure sensor goes bad, or the signals are faulty, this mixing ratio is disturbed. As a result, you might feel engine stall or sluggish acceleration.