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Weak Mechanical Fuel Pump Symptoms – Troubleshooting Guide

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Weak Mechanical Fuel Pump Symptoms – Troubleshooting Guide

Ahh, fuel pump – one of the most underrated parts of your vehicle. It’s the component that helps move gas from the tank to the engine. And if it fails on you, the car is not going anywhere. 

Here are some symptoms of a weak mechanical fuel pump to watch out for: 

  1. The engine sputters or stalls. 
  2. Loss of power when accelerating 
  3. The engine starts to surge. 
  4. You notice a decrease in fuel efficiency. 
  5. Difficult starts. 
  6. Sudden Stalls. 
  7. The check engine light comes on. 
  8. Engine misfires. 
  9. Exhaust smells like unburnt fuel. 
  10. RPMs don’t rise above a certain level. 

This article outlines some of the more common symptoms of a failing fuel pump. If you notice any of these happening to your car, it’s time to get to a mechanic and have them take a look. 

1. The Engine Sputters or Stalls

One of the most common symptoms of a failing fuel pump is when the engine starts to sputter or stall. This can happen when the pump isn’t getting enough gas to the engine or if something is blocking the flow of gas. 

When this happens, you could be looking at a problem with the pump, fuel line, or filter. Any of these can cause the engine to sputter or stall. Replacing the fuel pump is usually the best course of action for the DIYer, but a mechanic can better diagnose this and any other additional problems. 

It’s also worth noting that this symptom can be caused by other problems, like a bad spark plug or coil. So, if your car is sputtering or stalling, it’s best to get it checked out as soon as possible. 

Read: What Happens When the Fuel Pump Goes Out? 

2. Loss of Power When Accelerating

You might also notice a loss of power when you try to accelerate. This is another symptom of a failing fuel pump. If the pump can’t deliver enough gas to the engine, the car will start to lose power. 

Picture this: 

You’re driving along, hitting the gas to pass another car. But instead of accelerating, the car starts to slow down. You are not sure what is happening until you realize that the vehicle in front of you is now pulling away. 

This is a loss of power, and it’s caused by insufficient gas in the engine. If you’re having this problem, it’s time to get your fuel pump checked out. 

3. The Engine Starts To Surge

This one is the opposite of the loss of power symptom. Instead of a lack of gas in the engine, there’s too much. 

You’ll notice that the car will start to surge forward even when you’re not trying to accelerate. It can be pretty scary, especially if you’re driving in traffic. 

This surge is caused by an overabundance of gas getting into the engine. It’s usually because the fuel pump is on its way out. The good news is that it’s an easy fix, as long as you get to a mechanic before the fuel pump fails completely.

Read: How to Start a Car With a Bad Fuel Pump 

4. You Notice a Decrease in Fuel Efficiency

If you’ve been driving the same car for a while, you probably have a pretty good idea of how many miles a tank full of gas can take you. So, if you suddenly notice that you have to stop for gas more often than usual, something is probably wrong. 

One of the things that can cause a decrease in fuel efficiency is a failing fuel pump. If the pump isn’t working correctly, it can lead to gas being wasted in unnecessary surges. As a result, you’ll have to fill up the tank more often. 

Paying more to travel the same distance is never fun, especially now that gas prices are rising again. This is why it’s crucial to get your fuel pump checked if you notice a decrease in fuel efficiency. 

Read: What Are the Symptoms of Fuel Tank Vent Blockage?

5. Difficult Starts

If your car is cranking but not starting, it could be because of a weak fuel pump. The car will be hard to start if the pump can’t deliver enough gas to the engine. 

This is especially true if you try to start the car after it’s been sitting for a while. The pump will have to work harder to get the gas flowing, and if it can’t, the motor won’t start. 

If this problem is not so bad, the car may eventually start after a few cranks. But if the fuel pump is really on its last legs, you’ll probably have to get a tow to the mechanic. 

6. Sudden Stalls

If your engine stops receiving the right amount of fuel, it will stall. And this can happen without warning. This is usually because you ignored the weak fuel pump signs, and now the pump has stopped working altogether. If this happens, you’ll need to get the car towed to a mechanic so they can replace the fuel pump and check for other issues. 

At this point, you’ll pay for the towing, the new fuel pump, and the labor to install it. So, it’s much cheaper just to get the fuel pump checked out as soon as you notice an issue. 

7. The Check Engine Light Comes On

The check engine light is one of those things that no one wants to see. However, if you do, take your car to the mechanic. 

One of the things that can trigger the check engine light is a failing fuel pump. So, if you’ve been ignoring all of the other symptoms on this list, this is probably why. 

The good news is that the check engine light will go off once you get the fuel pump replaced.

However, many things can trigger the check engine light, so don’t assume it’s the fuel pump just because it is on the list. The best thing to do is to take your car to the mechanic and have them diagnose the problem. 

Read: Bad Fuel Pressure Sensor Symptoms

8. Engine Misfires

You already know how your car is supposed to sound when it’s running. So, if you start to notice that the engine is making strange noises, something is definitely wrong. 

One of the things that can cause engine misfires is a weak fuel pump. If the pump can’t deliver enough gas to the engine, the engine will start to misfire. The issue with this is that it can cause long-term damage to the engine if it’s not fixed. 

So, if you notice that your engine is misfiring, take it to the mechanic right away. They’ll be able to tell you if the fuel pump is to blame. And if it is, they’ll replace it before any serious damage occurs. 

9. Exhaust Smells Like Unburnt Fuel

This one usually comes along with misfiring, but it can happen on its own. 

If you notice that your exhaust is smelling like unburnt fuel, it’s a sign that your car isn’t burning gas properly. And this is usually because of a faulty fuel pump. 

Your engine is probably in pretty bad shape by the time this happens. You might drive a bit longer, but it’s not going to be long before the engine fails. Hence, if you notice this symptom, take your car to the mechanic right away. 

Read: How Often Should The Fuel Filter Be Changed?

10. RPMs Don’t Rise Above a Certain Level

You have to be pretty observant to notice this one. However, if you pay attention to your car’s RPMs, you might be able to catch this before it becomes a bigger problem. 

If your fuel pump is going bad, you’ll notice that the RPMs don’t rise above a certain level. And this level will be lower than it should be. 

For example, if your car typically redlines  at 6,000 RPMs, you might notice it starting to struggle at 5,500 RPMs. This is a sign that the fuel pump can’t deliver enough gas to the engine to keep it running efficiently. 

This issue usually happens at higher speeds, so you might not notice it until you’re on the highway. But, if you do, take your car to the mechanic and have them check the fuel pump. 

The above are merely a few of the signs that your fuel pump is going bad. Other symptoms can pop up. The best thing to do is pay attention to your car and take it to the mechanic at the first sign of trouble. You can get the problem fixed before it becomes a bigger issue. 

You can also DIY fuel pump replacement if you’re feeling brave. But, unless you’re mechanically-inclined, I wouldn’t recommend it.

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