8 symptoms of a bad fuel pump (& replacement cost)

the fuel pump supplies your engine with fuel and without it your engine would stop immediately. here's how to tell if your fuel pump is bad

symptoms of a bad fuel pump

the fuel pump is an important component of your vehicle. without it, your car would die imminently

in all modern gas and diesel vehicles, a fuel pump is necessary, whereas, in older vehicles, the function depends solely on gravity to deliver the fuel.

a fuel pump can be damaged or fail for various reasons, such as the consistent use of contaminated fuel or poor quality fuel.

in this article, you will learn the most common symptoms of a poor fuel pump, location, and replacement cost. let’s begin by taking a quick look at the signs you should look out for.

the most common symptoms of a bad fuel pump are engine hiccups, misfires, excessive smoke from the exhaust, and a stalling engine. you may also notice an illuminated check engine light on your dashboard.

this may give you some fast answers, but you do probably want to know more about the issues. luckily, here is a more detailed list of the 8 most common symptoms of a bad fuel pump:

bad fuel pump symptoms

1. car experiences hiccups

car hiccups e1609774936535

cars need fuel to drive, just as we humans need food. it is easy to understand how important fuel is, and it is also easy to see that your car will not meet your expectations if the correct fuel supply is not guaranteed.

if you press the accelerator and feel that your car has hiccups, you may have problems with the fuel pump.

the fuel pump may be choking due to inferior fuel, or the fuel pump may not be generating enough pressure to push the fuel forward into the system.

related: symptoms of a bad fuel pump relay & location

2. misfires

car misfires e1609774947173

an insufficient supply of fuel to the combustion chamber will not create enough chamber excitement to cause an explosion. no combustion means that the engine will not start at all. even if it does, you will find that it takes you a long time to reach ignition.

if you experience that your car has misfires or sounds like a tractor at idle, you might have low fuel pressure due to the fuel pump.

3. sudden engine shutdown or no starting condition

stranded car e1609774958505

the engine needs fuel to run, and if the fuel pump is bad, the engine won’t get any fuel. if your engine doesn’t start at all or having sudden engine shutdowns while driving, there might be a problem with the fuel pump.

if this occurs regularly, it is time to arrange a meeting with your local mechanic.

4. backfires

backfire e1609774966542

since a bad fuel pump can give an intermittent amount of fuel to the engine, you can experience misfires because of the too low fuel amount.

the engine can also get too much fuel, resulting in unburned fuel in the exhaust pipe, which will cause backfires from the exhaust pipe.

5. check engine light illuminates

check engine light

fortunately, modern cars are loaded with sensors that can detect any number of problems as soon as they occur. one of these sensors is a fuel pressure sensor that is intelligently measuring the fuel pressure. if an irregularity is detected, the sensor sends a signal to the ecu, which lights up the check engine light.

you can easily check the error code displayed by the check engine light through an obd2 scannerir?t=askamastermec 20&l=am2&o=1&a=b01mr7fzs1.

6. thick black or white smoke from exhaust

black smoke car

vehicles do not normally emit black smoke from their exhaust unless they are powered by diesel fuel. if your gasoline-powered car emits such smoke, there is usually engine damage.

one of the causes of black or white smoke is a defective fuel pump, making your engine get a rich fuel mixture. in most cases, a bad fuel pump is giving a lean mixture, so this is not a very common one.

7. turbocharger underperforms


first of all, not all cars have a turbocharger, but those with one have a bonus symptom. turbochargers work by compressing airs to rotate a turbine that delivers additional power to the engine.

turbos need time to spool air; this time is usually called turbo lag. so if you feel that there is a lot of turbo lag, your fuel pump could be a problem.

8. spark plugs will die sooner

bad spark plugss

fuel does actually cool down internal engine parts. with a too lean air-fuel mixture, you can actually make your spark plugs getting too hot. a defective fuel pump interferes with the internal workings of the engine.

the smallest damage occurs in the cylinder itself, and the smallest components take the greatest damage. this means the spark plugs may die before their time.

so if you feel that your spark plugs need to be replaced too soon, you may be dealing with a faulty fuel pump.

what is a fuel pump?

cars fuel pump

the fuel pump’s main function is to deliver fuel to the fuel injectors, injecting fuel into the combustion engine system. in most cases, carburetor engines use the function of mechanical fuel pumps, which are mounted outside the fuel tank and operate under low-pressure conditions.

apart from carburetor engines, diesel engines often use two main pumps to deliver fuel, which works electrically and improves performance efficiency.

one pump is installed inside the fuel tank, which delivers more fuel at low pressure, while another pump is installed near or inside the engine, which sucks in the required amount of fuel at a higher pressure.

for the maximum efficiency and proper functioning, the fuel pump operates under certain conditions that are electronically adjusted to optimize the combustion engine’s air-fuel mixture. if more fuel is supplied to the engine, the air-fuel ratio is disturbed, and all the fuel cannot burn efficiently.

fuel pump location

fuel pump location e1609825305346

the fuel pump is almost always located at the top and inside the fuel tank on newer cars. some cars have a cover to remove under the backseat or in the trunk to reach the fuel pump’s location.

unfortunately, you have to remove or lower the fuel tank to reach it for some cars.

some older cars do also have an external fuel pump located outside of the tank.

fuel pump replacement cost

the average fuel pump replacement cost is between $100 and $700, depending on the car model and labor costs. a fuel pump costs $50 to $400, and the labor cost is $50 to $300.

if you have a petrol engine with an electronic fuel pump, the fuel pump is often not very expensive. the expensive part is letting a mechanic replace the pump. the pump is often located inside the fuel tank, which means that there is a cover to reach it from under the back seat if you are lucky. but, there are car models you have to remove the whole fuel tank to reach it. you can imagine the time it takes.

in some cases, you can do it yourself if you have some experience, but remember it is a really nasty job and not good for your health.

if you have a diesel engine and want to replace the mechanical fuel pump, you can expect a much higher replacement cost. these pumps can cost up to $1500 if you are unlucky, and the replacement cost is often also very high. after this, you do often need an adjustment of these pumps also.