Your car’s fuel system relies on various components collaborating to deliver sufficient fuel to the engine. These components must be in good working condition to ensure enough fuel mixes with air in the combustion chamber. If one of them fails, you might notice several performance issues.
Among these components is the fuel rail pressure sensor. Like other fuel system parts, this sensor can malfunction and create fuel delivery issues. Besides replacing a faulty fuel rail pressure sensor, bypassing it can work as a temporary fix.
Our guide takes you through how to bypass a fuel rail pressure sensor in 5 simple steps. We’ll also discuss what this sensor does in the fuel system.
Answer 1: How the Fuel Rail Pressure Sensor Works
The fuel rail pressure sensor (FRPS) is an electronic device that continuously monitors fuel pressure inside your car’s fuel rail. It sends accurate fuel pressure readings to the engine control unit (ECU). Then, the ECU examines the data from this sensor and uses it to make necessary adjustments.
The goal is to allow the ECU to maintain optimal fuel pressure and efficient fuel injection timing. By adjusting fuel pressure and injection timing, your engine can work efficiently to produce more power while ensuring fuel efficiency.
The FRPS lies in the fuel rail – a high-pressure tube for collecting fuel from the pump. As the fuel flows through the rail, it will exert pressure on a diaphragm strain gauge. This pressure triggers a change in the resistance.
The sensor converts this resistance into an electrical signal to signify fuel pressure. Then, the sensor will send this signal to the ECU to ensure fuel pressure adjustment and injection timing. The sensor continuously monitors and sends updated fuel pressure data to the computer.
Answer 2: How to Bypass a Fuel Rail Pressure Sensor
If the FRPS fails, it can cause various performance issues like poor fuel economy and poor engine performance. The best solution to a bad FRPS is replacing it with a new one. However, if you’re in a situation where you can’t replace the sensor, you can consider bypassing it.
Let’s look at the steps to follow when bypassing a fuel rail pressure sensor:
Step 1: Locate the Sensor
You’ll find this sensor on the engine’s fuel rail, somewhere near the middle of this component. Start by locating the fuel rail below the intake manifold. Note that the exact FRPS’s location can vary from one car model to another. Your car’s manual can help you find its location.
Step 2: Disconnect the Sensor
After locating the FRPS, you’ll need to disconnect it from its wiring harness. Remember to start with the power source to avoid electrical mishaps.
Step 3: Examine the Wiring
The wiring that was connected to the FRPS might be damaged and prevent a successful bypass process. So, check the wiring to ensure there are no signs of fraying, wear, or damage.
Step 4: Bypass the Sensor
There are two methods of bypassing the fuel rail pressure sensor. You can either use an LED test light or a resistor.
Do as follows when using an LED test light:
- Connect your LED test light to the FRPS’s signal wire.
- Connect the LED test light’s alligator clip to the FRPS’s ground wire.
After successfully connecting your LED test light, you should see it illuminate to indicate you’ve established resistance. Establishing a resistance will trick the ECU into believing that the fuel rail pressure sensor is still at work.
Alternatively, do as follows to bypass the FRPS using a resistor:
- Connect one end of your resistor to the FRPS’s signal wire.
- Connect the other end to the FRPS’s ground wire.
And just like that, you’ve bypassed the fuel rail pressure sensor.
Step 5: Test Your Car
Start your car and check how it performs. If you’ve successfully bypassed the sensor, your engine should operate smoothly. This process should eliminate issues like starting difficulties, a check engine light, vehicle running rough, and poor fuel economy.
Answer 3: Safety Measures When Bypassing the Fuel Rail Pressure Sensor
You now know how to bypass a fuel rail pressure sensor. But how should you handle this task while ensuring you’re safe?
The fuel rail pressure sensor is an electrical device within the fuel system. When bypassing it, you must be cautious to avoid causing a fire hazard. Below are the safety measures you should adopt when bypassing the FRPS:
- Disconnect the battery: Disconnecting the battery’s negative terminal ensures no power flows to the electrical components. Doing so can help prevent short-circuiting when handling different wires.
- Turn off your car: You’ll need to turn off the engine to prevent fuel spillage. You can also remove the keys from the ignition to avoid accidental ignition.
- Relieve fuel pressure: Relieve pressure from the fuel lines before disconnecting the sensor. Doing so will help prevent fuel from spraying out.
- Well-ventilated area: Ensure you’re working in a well-ventilated area to allow dispersing of fuel vapors.
- Wear safety gear: Safety gloves will protect you from accidentally touching fuel with your skin. Use safety goggles to protect your eyes from fuel vapors.
Answer 4: Benefits of Bypassing the Fuel Rail Pressure Sensor
Below are the benefits of bypassing the FRPS.
Improved Gas Mileage
A bad fuel rail pressure sensor might send inaccurate data to the ECU regarding fuel usage. This may result in poor gas mileage. Bypassing this sensor ensures the engine receives the required fuel amount.
Better Engine Performance
Bypassing the FRPS ensures unrestricted fuel flow, allowing the engine to work more effectively. As a result, you’ll witness more power output and better acceleration.
No Engine Misfires
A bad FRPS will trigger engine misfires. Bypassing this sensor eliminates the causative factor of engine misfires, allowing your engine to become more stable.
Resolved Hard Starting
A faulty FRPS will cause more fuel to be delivered into the combustion chamber, leading to hard starting. Bypassing this sensor allows the fuel injectors to deliver the right amount of fuel, thus resolving a hard starting issue.
Question: Can You Drive With a Defective Fuel Rail Pressure Sensor?
You can continue driving with a bad FRPS, but doing so might cause more harm to your car. A malfunctioning FRPS will hurt your vehicle in the following ways:
- Engine starting problems
- Bad fuel economy
- Reduced power
- Poor acceleration
- Engine misfires
- Engine running rough
- Engine idling unevenly
Prolonged driving with a bad sensor can cause severe damage to the engine and fuel system.
Wrapping Up
We’ve shown you how to bypass a fuel rail pressure sensor in five easy steps. You can bypass this sensor using a resistor or an LED test light. Bypassing the sensor should be a temporary fix to help you get back on the road.
If you have a faulty FRPS sensor, ensure you replace it as soon as you reach the nearest workshop. A professional will also examine your car and fix any issues causing the sensor to fail.