Bad Fuel Pump Symptoms

Bad Fuel Pump Symptoms
The Drive and its partners may earn a commission if you purchase a intersection through one of our links. Read more. A fuel pump ’ s chief job is to deliver fuel from the storehouse tank to the engine, and works with multiple other car parts to accomplish that duty. That can make it difficult to know whether or not it ’ second fail, unless you know the symptoms of a badly fuel pump. The most significant key to diagnosing a car is listening and understanding how it normally works, runs, and acts on a daily footing. What sounds does it make ? What rattles ? What are its convention RPMs ? With this cognition base, and an heedful mentality, you ’ ll notice when the vehicle starts running irregularly.

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Realizing the fomite starts hard, struggles to maintain idle, or flex less power is the beginning footstep in accepting there ’ s an consequence and setting out to fix it. Because thus many car parts are interconnected and interdependent, diagnosis is not constantly a elementary exercise. It requires trial and erroneousness, and pinpointing the accurate reservoir much requires the process of elimination. That ’ s what we ’ re here to discuss, in regards to fuel pumps. Follow The Drive ’ s exhaustive scout to bad fuel pump symptoms and design out what the heck is going on with your drive .

What Is a Fuel Pump?

A fuel pump is a mechanically or electrically controlled mechanism that sends fuel from the gas tank car through the fuel filter to the fuel rail. From there, fuel is distributed to the injectors and sprayed into each locomotive cylinder combustion chamber. On older vehicles, the pump sends fuel to a carburetor .
The Acura Integra's fuel pump is located inside the fuel tank.
Acura Integra Service Manual
An Acura Integra diagram .

Types of Fuel Pumps

Automobiles have primarily transitioned away from mechanical pumps on the engine barricade in old cars to electric pumps inside the gas cooler on modern vehicles. Below, we break down the diverse types of pumps and how they work. Mechanical fuel pump : A mechanical fuel pump uses positive displacement with a piston or a diaphragm. In a cyclic carry through, the pump draw in fuel, traps it, then moves that fuel toward the carb and locomotive, and repeats the action. Electric fuel pump : An electronic fuel injection system on modern vehicles requires higher pressure, which is accomplished, in separate, by using an electric fuel pump quite than a mechanical module. here are a few examples of electric pumps :

  • In-tank: The majority of new vehicles sold today use fuel pumps that are located inside the fuel tank. This helps protect the module, and the gas helps keep it cool.
  • Inline: Much easier to replace than an in-tank pump, an inline pump is located between the gas tank and the engine and is installed within the fuel system track. These are often mounted under the car or in the engine bay.
  • Rotary vane: Like mechanical pumps, rotary vane pumps use positive displacement to move the fuel along. Inside a rotary vane pump, a rotor with “paddles” operates off-center within a cavity. Because it is off-center, it creates a crescent-shaped pocket of space that lets the fuel in. The vanes close the small amount of fuel as the rotor moves, and release the fuel once it crosses the outlet valve. Different types of vane pumps include rolling vane, sliding vane, flexible vane, and swinging vane. 
  • Gerotor: A gerotor pump also uses positive displacement but uses different parts to achieve that method. Within a gerotor pump, there are two interlocking gears, a toothed inner gear and an outer ring gear with smooth curved lobes. The inner gear is offset from the outer gear. Thus, when they rotate, small pockets of fuel can be trapped, pressurized, and released.

It is important to replace the o-ring when replacing a fuel pump.
Acura Integra serve manual .
A diagram of an Acura Integra fuel pump .

How Long Do Fuel Pumps Last?

fuel pumps are not part of a regular maintenance schedule and merely need to be replaced when they fail. Most fuel pumps should end well past 100,000 miles .

Symptoms of a Bad Fuel Pump

Though these symptoms could be sourced to a faulty fuel pump, that is not constantly the character .

Car Won’t Start

There are a master of ceremonies of issues that could prevent a car from starting, but a miss of fuel is one of the first things to check. If the fuel pump can ’ thyroxine air fuel to the engine, it won ’ thymine depart. Related post: How to Jump-Start a Car Without Cables


If the vehicle starts but runs rocky and possibly dies, the engine might not be getting enough fuel .

Car Dies Under Heavy Load 

If you test your fomite ’ sulfur limits, whether that be hard-driving or hauling supernumerary weight and the baron cuts off, it might be a symptom the fuel pump can not keep up with the driver ’ second demands .

Inconsistent and Unintended Acceleration

If the total of fuel international relations and security network ’ t by rights regulated by the fuel heart, a car could accelerate without remark due to an overage of fuel.

Decreased Fuel Efficiency

If you notice your vehicle is abruptly gulping more gas than usual, the fuel pump could be damaged and sending the incorrect amount of fuel .

Increased Engine Temperature

Should the fuel pump fail to provide the proper amount of gas to the engine, the engine could be overstressed, which could cause an guerrilla rise in temperature .
An in-tank fuel pump has an inlet valve and an outlet valve.
O’Reilly Auto Parts
A MasterPro Fuel Pump

Fuel Pump Inspection Safety

Working on your cable car can be dangerous and messy, indeed here ’ mho precisely what you ’ ll need to ensure you don ’ thymine die, get maimed, or lose an eyeball—hopefully .

  • Safety glasses
  • Mechanic gloves
  • Mechanic coveralls (optional)
  • Jack and jack stands if you need to drop the tank

Tools You’ll Need To Access Your Fuel Pump

If you need to replace your fuel pump or change its filter, you ‘ll need some basic tools to get you there. Most mod cars will have an entree gore in the proboscis or rear seats, but some older vehicles might require dropping the fuel cooler .

  • Multimeter
  • Socket set
  • Screwdriver set
  • Hose clamp pliers
  • Shop rags/microfiber towels
  • Air compressor or canned air
  • Container to catch excess fuel
  • Siphon pump if you want to drain the fuel

What’s the Easiest Way to Check a Fuel Pump?

A simple method acting to check if a fuel pump is turning on is to listen for it. Open the fuel door, remove the fuel cap ( if your car has one ), and turn the car ’ mho ignition to “ On. ” Put your ear next to the fuel doorway and listen for a humming randomness. If you don ’ metric ton hear any detectable action, the pump is likely not working .

Diagnosing a Fuel Pump Problem

Ask yourself these questions to narrow down the generator of your issues .

  1. Does the car have gas? 
  2. Is the fuel pump turning on?
  3. Is the fuel pump fuse bad? 
  4. Is the fuel pump relay fuse bad? 
  5. Is there a poor connection on the fuel pump? 
  6. Is the fuel filter clogged? 
  7. Are the fuel injectors clogged? 
  8. Is the fuel pressure in range?
  9. Does the fuel cap have a clean reliable seal? 

Related post: How to Clean Your Car’s Fuel Injectors

Tips for Fuel Pump Removal

Accessing and removing a fuel pump can be boring, so you want to make surely you do it correctly the first base time. Use these tips for a successful job .

  • Be sure to relieve any pressure in the fuel line.
  • Additionally, make sure there is no live electricity near the fuel tank.
  • Take a photo of the fuel pump or use a marker to note where it is seated within the tank. This will help you align the pump correctly when you return it to the tank.
  • There might be dirt and grime around the top of the pump. Make sure you clean this area thoroughly and eliminate anything that could fall into your tank and cause issues later. Compressed air is a great way to blow things off.
  • Many pumps use a locking ring, which might be difficult to remove. Read how to remove it, and be aware that it might have different locking methods, which might be snapped off if you aren’t delicate.
  • Inspect your fuel sending unit and float while you’re down there. Read more about fuel sending units in our guide, “Do I Need To Replace My Fuel Gauge If It’s Not Working?”

How Much Does It Cost To Replace a Fuel Pump?

Depending on the car and how previous the cable car is, fuel pump costs range from $ 50 to several hundreds of dollars .

How to Keep Your Fuel Pump Healthy 

You need your fuel to continue pump, pump, pumping it up like Joe Budden, so you don ’ t want to unintentionally damage the unit of measurement. These belittled steps should help keep it in crown form .

  • With in-tank pumps, the gasoline doubles as a coolant. If a tank is regularly low, you are unintentionally allowing your pump to withstand extra heat. Always regularly fill your tank completely every time.
  • Change the fuel filter according to the manufacturer’s recommended timeline. A clogged filter could create unintended pressure within the fuel system.

Sometimes You Need a Certified Mechanic

vitamin a much as The Drive loves to put the “ you ” in do-it-yourself, we know that not everyone has the proper tools, a safe workspace, the bare time, or the confidence to tackle major automotive repairs. sometimes, you precisely need quality repair work performed by professionals you can trust like our partners, the certifiable mechanics at Goodyear Tire & Service .

FAQs About Fuel Pumps

You ’ ve got questions, The Drive has answers !

Q: How does a car act when the fuel pump is going out?

A : If your fuel heart is going bad or has died, you will probable experience one or more of the many symptoms detailed above. These include worry starting, sputtering, decrepit performance, hapless fuel economy, poor people acceleration, and overheating .

Q: Would a bad fuel pump throw a code?

A : Although a bad pump itself doesn ’ t throw a code, the incorrect come of fuel sent through a car ’ sulfur fuel system could trigger sensors that anticipate certain levels and ratios of tune and fuel mixtures. indeed technically, yes, it ’ s possible to see a code as a result of a bad fuel pump.

Q: Can you drive with a bad fuel pump?

A : Because a bad fuel pump could cause unexpected drops in exponent or tied wholly shut the fomite down, we do not recommend driving with the cognition of a bad fuel pump .

Q: How do you clean a fuel pump without removing it?

A : fuel arrangement cleaners do exist, but even in the event that they actually do something ( don ’ t count on it ), it will plainly be putting the speculate off to a late time. Get it out of the way and do the full moon speculate nowadays before something bad happens late when you aren ’ metric ton expecting it .


Learn more about fuel tanks in this video about a Holley conversion .

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