Rajan Wilcox
There are many reasons why you might lose power at the fuel injector harness. The fuel injectors get their power from fuse #16 (25A) in the underhood fuse panel and through the ASD relay. If there is no power to the coil or injector, it could be that the relay is not turning on. It could also be that the injector is clogged, which will decrease the spray inside the cylinder, causing the fuel to not burn completely and creating a misfire. In some cases, the issue could be with the engine harness or a faulty computer.
| Characteristics | Values |
|---|---|
| Cause of loss of power | Dead/bad computer, faulty wiring harness, faulty ASD relay, faulty PCM, faulty ECU, faulty injectors |
| Symptoms | Engine not starting, engine running rough, misfire, injector not spraying properly |
| Diagnosis | Check for spark and fuel pressure, check for power at the injectors, test injector resistance, check for shorts in the wiring harness |
| Solution | Replace or repair faulty component, clean or rebuild injectors |
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What You'll Learn
A faulty computer
In some cases, a faulty computer may not provide the necessary signals or power to the fuel injector harness, resulting in a lack of fuel delivery to the engine. This can cause the engine to stall or fail to start. It is important to note that a faulty computer is just one of several potential causes of a loss of power at the fuel injector harness. Other possible causes include electrical issues, clogged fuel injectors, or problems with the fuel pump or fuel lines.
To diagnose a faulty computer, it is recommended to have the vehicle scanned for trouble codes or seek the assistance of a professional technician. They can perform thorough diagnostics and determine if the issue lies with the engine computer or other components of the fuel system.
It is worth noting that a faulty computer may not always result in a complete loss of power at the fuel injector harness. In some cases, it may cause intermittent or partial loss of power, leading to reduced engine performance, misfires, or decreased fuel efficiency.
Additionally, a faulty computer can affect the overall drivability of the vehicle. The fuel injectors play a critical role in providing the fuel required for the engine to run. If the engine computer malfunctions and disrupts the operation of the fuel injectors, it can lead to performance issues or even render the vehicle undrivable in severe cases.
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A faulty auto shutdown relay
If the ASD relay fails, the engine will not crank, and the vehicle will not start or move. This is because the ASD relay provides power to critical systems during ignition. While ASD failure is uncommon, it can occur due to wear and tear or frequent engine stopping and starting.
Symptoms of a faulty ASD relay include a complete loss of electrical power, as the relay controls the power supply to various components. In some cases, the vehicle may start but then immediately shut off due to a lack of fuel injection or spark.
To diagnose a faulty ASD relay, one can perform a test using an ohmmeter. With the relay removed, the resistance between terminals 85 and 86 should be checked, with a reading of 75 ohms +/- 5 ohms indicating normal function. Additionally, one can inspect the fuses and clean the ground connections to ensure they are not the cause of the issue.
If the ASD relay is indeed faulty, it will need to be replaced. The location of the ASD relay varies depending on the vehicle's make and model and can be found in the Integrated Power Module (IPM) or under the hood, dash, or another position. It is recommended to seek professional diagnosis and replacement to ensure the issue is accurately identified and addressed.
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A faulty fuel pump
There are several ways to diagnose a faulty fuel pump. One method is to check the fuel pressure by removing the cap from the Schrader valve behind the alternator and depressing the core. If no fuel squirts out, or if the fuel pressure is lower than the specified range, it could indicate a faulty fuel pump. Another way to diagnose a faulty fuel pump is to listen for unusual noises. If the fuel pump is damaged or failing, it may make unusual whining or buzzing sounds. Additionally, you can use a fuel flow meter to measure the volume of fuel delivered by the pump. If the pump is not delivering enough fuel within a specified time frame, it may be faulty.
Corrosion or damage to the fuel pump or its connectors can also lead to a loss of power at the fuel injector harness. In some cases, bypassing the connectors or repairing the wires may be a temporary solution. However, if the fuel pump is indeed faulty, it will need to be replaced to restore the vehicle's performance.
It is important to note that a loss of power at the fuel injector harness can be caused by various factors, including a faulty fuel pump relay, a clogged fuel filter, a faulty fuse, or issues with the engine control module (ECM) or powertrain control module (PCM). Therefore, comprehensive diagnostics, including voltage and resistance checks, are necessary to accurately identify the root cause of the problem.
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A clogged injector
Diagnosing a clogged injector can be challenging as the symptoms can be similar to low compression or ignition problems. However, there are some tell-tale signs and tests that can be performed to identify a clogged injector. One sign is a rough idle, which can be caused by a slow fuel leak due to the deposits preventing the fuel injector pintle from seating properly. Additionally, you can check for fault codes using a scanner to see if the system is lean, indicating a fuel delivery issue or a high concentration of alcohol in the fuel.
To confirm a clogged injector, it is important to rule out other potential causes, such as low compression or ignition problems. This can be done by checking for spark and fuel pressure, as well as examining the fuel injector flow to see if it is restricted or blocked. If the injector becomes completely clogged, it will create a constant cylinder misfire.
In some cases, a clogged injector may be accompanied by a loss of power to the injectors, which could be due to a faulty ASD (Auto Shutdown Relay) or a problem with the control side of the circuit. It is recommended to consult a mechanic or a professional for an accurate diagnosis and repair.
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A short in the harness
In the case of a short in the harness, one possible fix is to replace the ECM. However, this may not be the only solution, as other factors could be causing the short. It is important to visually inspect the harness and the ECM to look for any signs of trauma or damage. A meter capable of mS pulse display can be used to check for an injector pulse.
If the ECM is deemed to be faulty and requires replacement, it is important to note that it cannot simply be swapped out. The new ECM will need to be programmed correctly. This process can be complex, especially for certain car models and years.
To diagnose the issue, it is recommended to check for power at the ASD relay. If there is power, the ASD relay is functioning correctly, and the problem is likely on the control side of the circuit. It is also suggested to test the relay to see if it is turning on.
Additionally, it is worth noting that the ASD relay may be integrated into the Totally Integrated Power Module (TIPM), which is located in the fusebox under the hood. This module is not easily removable, and if a replacement is required, it may take some time to obtain the necessary parts.
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Frequently asked questions
There could be a number of reasons for this, including a faulty or dead computer, a faulty injector, or a problem with the wiring.
If your engine is running roughly, there may be an issue with the vehicle's fuel delivery system. A faulty injector can cause one of your cylinders to not ignite fully, throwing off the balance of the engine.
You can start by checking for smoke coming off the wire harness and inspecting the wiring for any signs of damage or chaffing. If you are unable to identify the issue, it is recommended to consult a certified technician for further diagnosis and repair.
