Car Troubleshooting

How To Start A Car With A Bad Fuel Pump

You’re driving your car home from work one evening and all of a sudden the engine jerks and sputters when you’re on the freeway. Your first thought probably is: Will I get home? The next thought is: What’s the problem with the car?

A jerking or sputtering engine when the car is moving at high speed is one indication that you may have a bad fuel pump. Will you be able to get home in this case? Probably.

Then what happens? You don’t have any do-it-yourself skills so that car is going to have to get to a service station or auto mechanic to be repaired. Will you be able to start the car tomorrow and get it to a mechanic? The answer is probably yes. But it could be somewhat of a hassle.

Obviously, the methods of starting a car with a bad fuel pump is possible, it is not a permanent fix, but, yes, you’ll be able to drive the car to a local mechanic.

Still, the task is not an easy one and involves using instruments commonly found in a mechanic’s toolkit. You’ll need a fuel pressure gauge and know how to use it.

You will also need to perform certain tasks more commonly performed by a mechanic or a mechanic in training, not someone who has very little do-it-yourself skills. Yes, it’s difficult. But it can be done if you follow instructions.

What Is A Fuel Pump?

A mechanical pump, the fuel pump operates off the motion of the engine. A diaphragm is mounted to the exterior of the fuel tank and expands and contracts as the engine is working, creating low pressure that pushes the fuel from the tank into the engine.

The actual fuel pump is situated in the fuel tank and features an electromagnetic motor that generates high-pressure force that pushes the fuel into the engine. These pumps are usually in cars that include a carburetor and fuel injection systems.

The fuel pump is a reliable piece of equipment because it is driven directly by the motion of the engine and contains only a few moving parts. Because they are so simple in design, any problem that occurs with it is easy to diagnose and repair.

Most problems with fuel pumps occur because the diaphragm is damages in some manner, which interrupts the pressure system from working in balance.

These pumps are commonly connected to an electronic control system that features many moving parts. The multitude of parts increases the possibility that the pump will fail.

Signs Of A Faulty Fuel Pump

Indications that your fuel pump is faulty include:

  • The engine of your car jerks or sputters at high speeds.
  • The car loses power when you attempt to accelerate.
  • The car loses power traveling uphill or when towing a load.
  • The engine of the car surges.
  • The engine won’t start.
  • The car’s engine frequently overheats.

The Engine Jerks Or Sputters At High Speeds

If the engine of your car sputters or jerks while driving on a freeway or Interstate, then it could be possible that the fuel pump can’t supply a smooth flow of fuel to the engine and the engine receives only air periodically.

The interruption of fuel flow causes the engine to skip power strokes, forcing it to sputter and jerk. When the fuel pump is experiencing early signs of faulting, the sputtering may last for only a minute or so and then the engine responds normally. 

The Car Loses Power When You Accelerate

When the car is accelerated, the engine requires more fuel and this forces the fuel pump to labor harder and it may not be able to keep up with the increased demand. The engine is starved of fuel as it attempts to accelerate. 

The Car Loses Power Traveling Uphill or When Towing A Load

Driving a car up a hill or when you’re towing a load puts an extra strain of the engine and it requires more fuel.

When the fuel pump is not working properly, it can’t supply the increase in fuel the engine requires. The condition causes major strain on the pump causing it to fail. It isn’t able to supply a steady stream of fuel to the engine resulting in loss power.

The Engine Surges

As the fuel pump wears out, the components begin to fail at different times. When this imbalance occurs and becomes great enough, the pressure in the fuel lines become inconsistent. As a result, the engine will accelerate for a few moments even if you don’t press the gas pedal. 

The Engine Won’t Start

If you ignore the signs of a failing fuel pump, then, over time, it will fail completely. Once the pump totally fails, then it can’t supply the engine any fuel at all and the car won’t start.

Diagnosing A Bad Fuel Pump

If you have rudimentary do-it-yourself skills, then you probably will be able to diagnose a problem fuel pump. Steps to perform the analysis include:

  • Ensure that the car’s battery is fully charged.
  • Use a test light to ensure that the fuel pump fuse is in proper working order.
  • Check the fuel pump pressure.
  • Locate the fuel pump and test its power and ground.

1.Ensure That The Battery Is Fully Charged

The fuel pump gets its power from the car’s battery. So, it is essential for the battery to be fully charged for the pump to get the necessary power it needs. 

2.Use A Test Light To Check The Fuel Pump Fuse

First, check to see if the test light is working. To do this, connect the lead end of the test light to the negative battery terminal and the positive lead to the battery’s positive terminal. If the test light goes on, then the test light is working properly.

Now, find and open the fuse box and test each fuse. This test is to determine whether or not you have a blown fuse.

If the test proves that the fuse is not getting power, then this could be a sign that the fuel pump is extracting too much amperage.

It could also mean that the ground connection has a short. In this case, replacing the bad fuse is just a temporary fix. Still go ahead and replace the old fuse with a new one. Then check the fuel pump’s pressure.

Most cars that feature an internal combustion engine use an electric fuel pump that supplies the high fuel pressure needed to get the fuel to the engine.

The normal pressure of a fuel pump is between 50 psi and 60 psi. Take a few minutes to check the Owner’s Manual to discover what your particular model’s fuel pressure should be.

3.Check The Fuel Pump Pressure

To test the pressure on the fuel pump, find the service cap on the fuel rail. It should be near the fuel injectors. Remove the cap to expose a Schrader valve and connect the fuel pressure gauge to it. Turn the ignition key on and check the gauge reading. It should go to between 45 psi and 60 psi.

4.Locate The Fuel Pump And Check Its Power And Ground

If the fuel pressure gauge indicates that there is no pressure in the fuel pump, then locate the fuel pump.

On most cars, it’s inside the fuel tank. You can access it from the back seat. Remove the seat base cushion to get to the pump. If the pump is not there, then it may be on the exterior of the fuel tank.

After you gain access to the fuel pump, then search for the connector that provides its power.  Slightly wiggle the pump, then loosen the connection and pull the pump out.

Now look for a connector that features two thick wires and two thing wires attached to it. The thick wires are for power and ground. The thin wires are the float or level sensors that sends signals to the gauge cluster on the dashboard.

Take a pair of jumper wires and attach one to the power wire and the other to the ground. Connect the other ends of the jumper wire to the test light to complete a circuit.

Attach the ground wire to the lead end of the test light and the power wire to the tip of the test light. Have a friend or family member turn on the ignition key as you continue to hold the connection.

If the test light goes on, then you have good power and ground in the pump. This should confirm that you have a faulty fuel pump that is not pressurizing the fuel that travels from the pump to the engine. You’ll need to replace the fuel pump. 

Starting The Car Despite A Failing Fuel Pump

If you don’t allow the problem to fester too long, then you should be able to start the car despite the problem and get it to a local mechanic.

There are a few methods you can use to start the car under this condition. However, as noted earlier, they are not permanent fixes. It is essential to get the car to a mechanic as soon as possible so that he can repair or replace the pump.

To start your car with a failing fuel pump you will need a fuel pressure gauge.

The pressure gauge monitors the performance of the fuel system and assists in determining whether or not it is working properly.  The gauge also helps to prevent the fuel pump from getting damaged because it measures the fuel pressure in the engine.

To put yourself in a position to start your car, attach the fuel pressure gauge to your car’s engine. This will allow you to start the fuel pump regardless of its condition.

Another method that can be used to start a car with a faulty fuel pump is to apply external pressure. The external pressure serves as a substitute to the pressure the fuel pump is unable to provide. 

If your car’s engine frequently overheats, then the fuel pump may be bad. You won’t be able to start the car again until the engine is allowed to cool.

So, turn off the ignition and wait for the temperature to drop on the temperature gauge on the dashboard.

Then try starting it again. When the car’s engine is cool, the fuel pump doesn’t require the proper pressure and heat. Still, you need to maintain the temperature so that you can get the car to a mechanic.

Maintaining Your Fuel Pump

You should be maintaining the fuel pump of your car to assure that it will last longer. Some maintenance tips include:

  • Purchase on high quality fuel from high-volume stations.
  • Perform a regular check of your car including the fuel pump.
  • Don’t leave the fuel tank empty because it can result in overheating of the engine and damage it as well as the fuel pump.
  • Keep your fuel tank at least a quarter full.
  • Include fuel ejector cleaner in your gasoline to keep the engine clean.

Final Thoughts 

Experiencing problems with your car due to a faulty fuel pump is something that no one would want to experience while driving their car.

That’s why you should be proactive when it concerns your car’s fuel pump and other parts of the car to maintain things properly when they are supposed to be. 

By including the fuel pump in the maintenance of your car these problems can be avoided and you’ll know when it’s necessary to replace the pump when the need occurs.

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