The most common reasons behind no power from ECM to fuel pump relay are loose connections, damaged fuel pump relay, and faulty ECM.
Keep reading this guide to find out more about these issues in detail and how you can fix them. Before getting started with that, you need to know how the fuel pump relay works and how to identify if it’s not getting power.
You’ll also learn how to fix the fuel pump fuse if it’s blown which is also a common issue that keeps the fuel pump from getting power. Let’s begin.
Table of Contents
How Does The Fuel Pump Relay Work
The only job of the fuel pump relay is to give power to the fuel pump. It gives power to the fuel pump when the ignition is turned on and shuts off that power supply once the ignition is turned off.
Note: You can also read No Check Engine light when key is in on position.
How Do You Know If Fuel Pump Relay Isn’t Getting Power
There are some common symptoms that you’ll notice when the fuel pump relay isn’t getting power. Here they are:
Check Engine Light
The ECM communicates with all the sensors and relays in your car and turns on the check engine light when it suspects that something is wrong. The first thing that’ll most likely happen when your fuel pump doesn’t get power is that the check engine light will be on.
A faulty fuel pump relay won’t give proper power supply to the fuel pump and it’ll mess up the fuel delivery. That’ll lead to issues in the combustion chamber and the acceleration will be rough.
A whirring noise normally comes after you turn on the ignition. You won’t hear any sound from the fuel pump as it won’t be getting any power.
Engine Stalling Or Dead
Your engine can stall if the connection to the fuel pump relay has gone bad. It may also die and fail to start when the fuel pump relay doesn’t get power.
The easiest and guaranteed way to know if your fuel pump relay has power is to check with a multimeter. If the multimeter doesn’t light up, it means the fuel pump relay isn’t getting power and you should find out what’s causing it.
No Power From ECM To Fuel Pump Relay [3 Easy Fixes]
The fuel pump in an engine is operated through the fuel pump relay. And what sends power to the fuel pump relay? It’s the Engine Control Moule (ECM). When the fuel pump relay doesn’t get power from the ECM, the fuel pump cannot supply fuel to the engine and the car won’t start.
1. Loose Connections
The fuel pump relay not engaging issue is often caused by loose connections in your car. If the fuel pump relay itself is loose or one of its battery connections is loose, it won’t get power.
Check the connection of the ECM to the battery and the ECM to the fuel pump relay. Check the wires as well and make sure everything is secured tightly. If there’s an issue with these connections, it needs to be fixed.
If any of the connectors are loose, the first thing to do is to clean them and see if they can form a tight connection. If that’s not happening, it’s a good idea to replace it. The same thing applies to the wires.
2. Damaged Fuel Pump Relay
The fuel pump relay not getting power issue can be caused if the fuel pump relay itself is bad. That means the ECM is doing its job correctly but the problem lies with the relay.
What happens if your fuel pump relay goes bad? The fuel pump gets power from the fuel pump relay. It won’t get power or work if the fuel pump relay gets damaged or corroded.
You can test out your fuel pump relay by swapping it with another relay that works properly and also has the same part number. If the swapped relay doesn’t work, that means the problem isn’t with your fuel pump relay. But if it works, you have a damaged fuel pump relay.
You can bypass the fuel pump relay as a temporary fix and see if your fuel pump gets power. Connect the load side pins 30 and 87 with a jumper wire and bypass the relay. Your fuel pump will run if the problem is caused by a faulty fuel pump relay.
You need to replace the faulty fuel pump relay with a new one so that it can get power and start your car properly. It’s not too much of a concern as you can replace it yourself and it’ll only cost you between $10 to $30 to get a new fuel pump relay.
3. Faulty ECM
Another reason why the Fuel Pump Relay won’t get power is when the ECM itself is faulty. A common problem with ECMs is that they won’t send the ground circuit to the fuel pump relay.
It can be an intermittent problem. That means sometimes the ECM will give the ground circuit and sometimes it won’t. Your car won’t start when the fuel pump doesn’t get the ground circuit from the ECM.
You’ll have to replace the ECM if it has gone bad. But there are two ways you can go about it- one method is relatively cheap and the other is expensive.
The first thing you should do is to find a dealer who knows how to reprogram the ECM. Instead of replacing your ECM with a brand new one, he can reprogram another used ECM for your vehicle.
Expert dealers have BDM programmers that allow them to reprogram the ECM. If they have used ECM with the same part numbers, they can read the information from your ECM and reprogram the other one. You can use it and save a lot of money by not buying a new ECM.
But if you can’t find a dealer who reprograms ECMs or you don’t want to install a used ECM on your car, you can get a brand new one. A brand new ECM is expensive but you’ll get more out of it compared to a used one.
How To Fix No Power To Fuel Pump Fuse
Besides the fuel pump relay not working, another common reason for the fuel pump not getting power is the fuel pump fuse. The fuel pump fuse connects the fuel pump and the ignition switch.
When a large amount of electricity passes through the fuse to overcome the initial resistance, it gets blown. Locate the fuel pump fuse, see if it’s blown, and replace it with a new one to fix this problem.
How much does it cost to fix the fuel pump relay not getting power?
If the fuel pump relay not working can be solved by changing wires or connections, it’ll cost around $20 to $30. But for a more complicated issue like a damaged ECU, it can easily cost a few thousand dollars.
What is fuel pump priming?
The fuel pump operates for a few seconds to ensure the fuel lines are filled with pressurized fuel when you turn on the ignition. It happens before you crank the engine and it’s called fuel pump priming.
Can an ignition switch cause no power to the fuel pump?
The ignition switch is connected to the fuel pump. If the ignition relay shorts or burns out or fails to operate for any reason, it’ll cut the power supply to the fuel pump.
What would cause a fuel pump not to turn on?
The most common reasons for a fuel pump not turning on are blown fuel pump fuse, faulty fuel pump relay, wiring issues, ignition issues, and damaged ECU.
Where is the fuel pump relay fuse located?
The fuel pump relay and fuse are generally located in the fuse box under the dashboard in most cars. But it’s also common to find them in the fuse box located in the engine bay.
The fuel pump is the heart of the car and it’s frustrating when it doesn’t operate properly. But now you know the main reasons that cause no power from ECM to fuel pump relay and how you can fix each of these issues.
Diagnose your fuel pump relay in the steps shown in this guide to identify the exact problem behind the issue and solve it. Leave a comment below if you have any more questions about fuel pump relays.