A weak fuel pump will have symptoms like a car not starting, wasting gas, or lack of acceleration or power while driving and it may not turn on the check engine light. In this article and video, you’ll find out what can cause a fuel pump to fail, how to tell if you have a weak fuel pump, and what you can do to diagnose and fix it yourself.
Symptoms of a Bad or Weak Fuel Pump
Car Is Wasting Gas or Losing Power While Accelerating
If there’s a problem with the fuel pump, you may find your car has trouble accelerating as gas isn’t getting to the engine efficiently. It might feel like your engine is hesitating to accelerate or there’s a lack of horsepower. You may also notice a drop in fuel mileage from wasted gas.
If you’ve tried diagnosing other parts like the ignition coils and still have this problem with no check engine light on, a weak fuel pump will likely be causing these symptoms.
Car Won’t Start or Has Difficulty Starting
If there’s a problem with the fuel pump, you may find yourself cranking the engine more to start it, or it might not start at all. Having an assistant tap the fuel tank as you crank to the car is a temporary fix and a sign the fuel pump is clogged, but the long-term solution to fix a fuel pump causing this is to replace it.
What Causes the Fuel Pump to Cause a No-Start?
The gas pump pumps gas from the fuel tank into the injector rail. The pressure builds up and is held to keep the injectors ready so when the engine is started the fuel will spray into the cylinders.
The fuel pump has a module that’s a reservoir that fuel sits in once the pump is submerged. It has a meter that measures the fuel level and sends a pulse to indicate the level of fuel in the tank. The pump on the sending unit will be near the pickup screen
The fuel pump will have a magnet and actuator. Brushes on both sides of the actuator spin and create a magnetic pulse. The pump itself is submerged in metal casing. It has ground and power wires and connects to the fuel supply line. There’s also a pickup screen that acts as a filter.
Fuel pumps are a turbine style, and it has small parts that spin and suck up the fuel. If you’re having issues starting your car, contaminated gas can cause dirt to stick in these passageways, and this can cause the engine to not start.
Black Smoke from the Exhaust
Black smoke from the exhaust could mean the fuel pump is faulty. Like problems with fuel economy and a lack of acceleration while driving, it may not turn on a check engine light.
Check Engine Light
You may not or may not have a check engine light turn on along with these symptoms if the fuel pump is weak or faulty. If there is a check engine light for a weak fuel pump, it’s usually because the engine is running poorly with a rich or lean condition.
How to Prevent Future Problems with the Fuel Pump
Use Treated Gas
To extend the life of the fuel pump, don’t buy cheap gas without treatment that could damage the fuel pump. Use the right gas for your vehicle.
More on the different types of gas
Don’t Run Low on Fuel
Running the car with a low fuel level can damage the fuel pump. Gas cools the fuel pump down, and running on low on fuel will heat the magnetic turbine and electrodes and wear out the brushes on the pump faster.
How-to Videos: Learn to Fix Fuel Pumps and More
You can learn how to diagnose and replace your own fuel pump with our how-to videos. We have thousands of videos with tips from experienced mechanics to help you diagnose a faulty fuel pump, and replace them and other parts on many different models.
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