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Should A Fuel Pump Run Continuously?

The fuel pump plays a vital role in the performance of a motor vehicle. Without it, fuel can't navigate its way to the engine for it to run. So, does that mean that a fuel pump runs continuously? We have taken the time to answer this question in this article.

The fuel pump should only run continuously if the engine is running. The fuel pump will also run if the engine is off, but the ignition key is still in the on position. When the key is set to the on position for an extended period, it isn't suitable for the fuel pump to run continuously in this scenario. Therefore, the fuel pump will only turn off when the engine and the ignition key are off.

It is essential to know the signs of a properly functioning fuel pump. If the fuel pump isn't working correctly, it can constantly run your fuel tank empty. In this article, we will take a closer look at the mechanical functions of a fuel pump and how it should and shouldn't work. In addition, we will give you an outline of the tell-tale signs of a bad fuel pump, so keep reading!

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Woman hand put key into the ignition and starts the car engine, Should A Fuel Pump Run Continuously?

Should A Fuel Pump Run Continuously?

The fuel pump runs while the engine is running, but it also runs when the key is turned on. So, does that mean that a fuel pump should run continuously? The answer to this question is no. A fuel pump should not run continuously.

Why? Well, for starters, your vehicle's alternator needs the power to keep your battery charged up. The alternator needs to recharge the battery because the fuel pump draws energy from it to run.

Therefore, when you leave your headlights on overnight or for an extended period, your fuel pump is running without the benefit of a charge (from the alternator). This can cause damage to your vehicle's battery in certain circumstances.

The second reason a fuel pump should not run continuously is that it can cause excessive wear and tear on the components of your vehicle's fuel system, such as the fuel pump itself. Again, this doesn't mean that you will damage anything by running your car with the key turned on or the headlights left on all night, but if you do it regularly, you will notice that your fuel pump will wear down quickly.

The last reason you shouldn't have the key turned on with the engine off is that the hard starting of your vehicle in winter can be attributed to this practice. Cold weather can cause problems for any electrical part in your car, mainly when it's not being used. The fuel system is not an exception to this rule.

Plus, when your battery is drained or struggling to get your engine started in cold weather, this places additional stress on the fuel pump. This means it will have to work harder and faster to overcome these problems, thus wearing down much quicker.

Driver holding car key starting the car, Can You Turn The Key Off While Driving?

Turn the key to Accessory Position Instead

If you insist on running the key while the engine is off (to listen to the radio etc.) for an extended time, you can turn your vehicle's ignition key to the accessory position. However, if the engine is cold, it will take a few minutes to warm up enough to operate the fuel pump at total capacity.

Another scenario where a fuel pump runs indefinitely is when there's a problem with your car's gas gauge or its sending unit. For example, if your fuel gauge reads inaccurately, it can cause the fuel pump to run or stop running erroneously. If this continues for an extended period, the fuel pump could die because it is used too much.

This problem with your car's gas gauge or sending unit should be fixed as soon as possible if you notice that your vehicle's fuel pump is running nonstop.

Why does my fuel pump stay running?

If your fuel pump is running when it shouldn't be, some things could be causing it. The fuel pump should only be running when the engine is running and relaying fuel from the fuel tank to the engine. If the fuel pump runs continuously when the engine and the ignition key are off, the list below could be the culprits.

Fuel pump relay problem

If you notice that your fuel pump is running all the time, you should check the fuse panel and the relays because this can indicate a problem with one of them. Since it's easy to determine which relay controls other parts in your cars, such as other circuits and components, replacing any bad fuses or relays will get your car's fuel pump running again.

You can also check the wiring for any breaks and ensure that all the connections are secure to avoid your vehicle's electrical system problems.

Young stressed man having trouble with his broken car

Bad fuel pump

Sometimes, a bad fuel pump will cause symptoms such as difficulty starting the engine or trouble getting it to turn over at all. The fuel pump can also not deliver enough pressure to the fuel system. This means that if you notice these problems, you should have your vehicle's fuel pump checked as soon as possible.

Fuel filter problem

If none of the problems outlined above apply to you, it may be time for a new fuel filter. A clogged or dirty fuel filter can restrict the flow of fuel, which in turn can prevent your fuel pump from working.

Fuel pressure regulator problem

Another cause for a constantly running fuel pump is a problem with your gas's pressure or flow rate. If this is the case, you should have it checked right away because an incorrect amount of gasoline reaching your engine can cause problems with the carburetor or pressure regulator.

Fuel pump wiring problem

If you've checked all of the above, then there may be a problem with the wiring for your fuel pump. A malfunctioning wire can either prevent your vehicle from starting at all or cause the fuel pump to overheat if it doesn't turn off.

What turns the fuel pump on and off?

When you turn your car's ignition key to start it, the starter sends a signal to the fuel pump relay. This causes the relay to send voltage to either your car's fuel pump or cause it to stop sending voltage and de-energize. So the fuel pump will either start sending gasoline to the engine or stop doing so, depending on what it's told to do.

The current has to run through several switches until it gets to the fuse box to get your car started. Two significant switches control whether your vehicle's fuel pump is energized or not: the ignition switch and the fuel pump switch. The ignition switch is located near your steering wheel, and it sends voltage to the fuel pump relay when you turn the key.

This causes either your car's fuel pump to start sending gasoline to the engine or causes it to stop doing so. The fuel pump switch is also located near your steering wheel, and it has two positions: on and off.

When your fuel pump switch is on, the car's fuel pump is sending gasoline to the engine, and when it is off, there's no power going to your car's fuel pump, and thus it stops sending gasoline to the engine.

What are the signs of a bad fuel pump?

A fuel pump will typically last anywhere between 100,000 and 200,000 miles, so if you are in that ballpark mileage, there are some signs to watch for if you suspect your fuel pump is going bad. A bad fuel pump will usually cause one or more of these problems:

  • Your car won't turn over, and it starts up slowly.
  • It has trouble turning the engine over, and it starts up slowly.
  • It seems like your vehicle's engine can't get any power to start up.
  • The ignition key clicks, but the engine doesn't turn over.
  • The fuel pump makes a humming sound instead of running quietly.

If you notice any of these signs when operating your vehicle, then contact a trusted certified mechanic!

Can a fuel pump turn on and still be bad?

The short answer is yes, a fuel pump will turn on and still be bad. When the ignition key is turned to start your engine, that sends voltage to the fuel pump relay, which causes either the car's fuel pump to start sending gasoline to the engine or it stops doing so, depending on what it's told to do.

Sometimes this relay can become stuck in the on position and continue to send power to the car's fuel pump, which causes it to run all of the time. If this is happening, then your car's engine won't start up, but the fuel pump will keep running, and that makes a humming sound instead of operating quietly as it should.

Also, when your vehicle starts up, your fuel pump relay should de-energize your car's fuel pump. This can sound like a clicking noise. If you drive too far without having the engine checked, it will overheat and need to be replaced.  This isn't good for anything, especially not its fuel pump.

Single woman drives car holding steering wheel low gas commuter

Final Thoughts

Overall, the fuel pump is an asset to the functionality of a vehicle. Without it, you won't be making it to your destination. Therefore, it is essential to have your fuel pump checked if you notice any signs of a bad fuel pump mentioned in this article!

If you like this article, then you should also check out:

Can A Fuel Injector Stop A Car From Starting?

5 Of The Best Fuel Injector Cleaners For Diesel Engines

Do Cars Consume More Fuel In Summer Or Winter?

thomas shafer

Tuesday 20th of September 2022

My experience with modern-technology

My motorhome (454 GMC) has 'TBI' fuel injectors. Two lines from the tank. #1 fuel-pump to the TBI, and #2 TBI return back to the tank. There is a built-in-pressure-relief valve (simple non-adjustable-spring valve) that maintains the constant fuel pressure. There are no fancy regulators or other devices to control fuel pressure. The fuel pump runs when the engine runs. At idle, the excess pressure forces open the spring-valve and fuel is pumped back into the tank. Meaning there is fuel constantly circulating between the TBI and thirty-feet away fuel-tank. Thats CRAZY & STUPID ! This explains why most old motorhomes burn to the ground. Then scrapped ! (Burned vehicles are rarely seen in junk-yards).

Today I'm learning about the fuel system on my Honda ST-1300 motorcycle. Its the same stupid setup, but with added safety 'valve' in the computer, which switches the pump off/on. Thats comforting,,, the pump works from 50 to 80 PSI !

My V8 Durango has a similar setup with the added 'fume-control'. This device absorbs gasoline fumes and releases the liquid back into the tank. The tank-filler-cap is pressurized so that no fumes are released. I noticed a gasoline odor, and found a leaking hose under the rear-passenger floor, the obvious place to mount a 'fume-controller'.

My 77-year-old automobile is all-metal (no plastic tanks or hoses) and a mechanical fuel pump to a small carburetor on the engine. I think I'll drive it today.

GrandDad said "you will get hurt, its easy,,, and you will learn not to get burned, cause that really hurts".