Fuel Pressure Without Injector Juice: What's The Deal?

If you have fuel pressure but no power to your injectors, there may be a wiring or connector problem in the harness. It is recommended that you check for a fusible link between the relay and the tributaries, which in this case is a blue one. If your fuel pump is powering but your injectors aren't, it is likely a wiring or connector problem. The EGR and Thermactor solenoids are also powered off the same feed, so it is worth checking if they are fed. If your injectors have sufficient power but are not operating as expected, there are three possible causes: a malfunctioning injector fuse, a defective injector power relay, or a bad wiring harness.

A blown fuse could cause the engine to stall

It is important to identify the root cause of a blown fuse to prevent it from happening again. In some cases, a blown fuse may be the result of a larger issue, such as a damaged wire harness. If the new fuse blows, it is likely that there is an underlying issue with the wiring harness that needs to be addressed.

To check if a fuse is blown, you can either visually inspect each fuse, looking for any signs of damage, or use a test light to confirm continuity. If the fuse is blown, it will need to be replaced before attempting to start the engine again.

In the case of fuel injectors, a blown fuse can cause the engine to stall or not start at all. This is because the fuel injectors rely on electrical power to function properly. If the fuse that supplies power to the fuel injectors blows, they will not receive the necessary power to operate, resulting in the engine stalling or failing to start.

It is important to note that a blown fuse is just one of several potential causes of fuel injector issues. Other possible causes include a defective injector power relay, a bad wiring harness, or a problem with the ECU (engine control unit). Troubleshooting fuel injector issues can be complex, and it may be necessary to consult a professional mechanic or auto repair shop for an accurate diagnosis and repair.

A defective injector power relay

To troubleshoot a defective injector power relay, you can perform the following steps:

• Locate the injector power relay: The injector power relay is usually found in the fuse box under the hood or dashboard. Refer to your vehicle's service manual to identify its exact location.
• Check for voltage: Use a multimeter to check if the relay is receiving voltage. If there is no voltage, there may be a problem with the wiring or the fuse.
• Test the relay: With the key in the "on" position, test the relay for power at two of the sockets. If there is power at two of the wires, the relay may need to be replaced.
• Inspect the wiring harness: A defective injector power relay could be caused by a damaged wiring harness. Inspect the wiring harness for any signs of damage or corrosion.
• Replace the relay: If the relay is defective, replace it with a new one. Make sure to purchase a high-quality, compatible replacement.

It is important to note that working on fuel injectors can be complicated, and it is always recommended to consult a professional mechanic for assistance if you are unsure about any part of the process.

A bad wiring harness

In the context of your fuel injectors, a bad wiring harness can result in a loss of signal to the transmission control module (TCM), leading to gear shifting issues, transmission slipping, and even overheating due to improper gear shifting.

Diagnosing a bad wiring harness can be a complex task and often requires the expertise of a professional mechanic or auto electrician. They will need to perform a thorough inspection and possibly run some tests to pinpoint the exact cause of the issue.

If you suspect a bad wiring harness, it is essential to have it inspected and repaired as soon as possible to ensure the safe and proper functioning of your vehicle.

Malfunctioning camshaft and crankshaft position sensors

If you have fuel pressure but no power to the injectors, it could be a wiring or connector problem in the harness. However, it could also be due to malfunctioning camshaft and crankshaft position sensors. These sensors are crucial for the ECU (engine control unit) to send signals to your injectors.

The camshaft position sensor monitors the camshaft speed and position and sends this data to the ECM. The ECM then determines the amount of fuel needed and the timing of the spark. A failing camshaft position sensor will provide inaccurate data to the ECM, causing the engine to consume more fuel. This can lead to stalling, rough idling, hesitation during acceleration, and even the car not starting at all.

The crankshaft position sensor is equally important, as it helps the ECU control the fuel injectors and determine the right amount of fuel necessary for optimal engine performance. A faulty crankshaft position sensor can cause problems with crankshaft positioning and ignition spark timing.

If you suspect that your camshaft and crankshaft position sensors may be malfunctioning, it is best to consult a professional mechanic for a thorough diagnosis and repair.

Drive Circuit (PCM) failure

A rare cause of a lack of pulse to the injectors is a drive circuit failure, also known as a Powertrain Control Module (PCM) failure. This can cause problems with crankshaft positioning and ignition spark timing.

If your car is suffering from these issues, it is recommended to take it to a dealership for a professional diagnosis and repair. If you are facing an emergency, you may be able to get the engine started by pressing the gas pedal to the floor when cranking the engine. This may trigger the driver circuit to start the engine, despite the challenges present.

Other possible causes of a lack of pulse to the injectors include:

• Malfunctioning camshaft and crankshaft position sensors
• A blown fuse
• A defective injector power relay
• A bad wiring harness

Frequently asked questions