How To Test Lift Pump On 5.9 Cummins?

How to Test a Lift Pump on a 5.9 Cummins

The lift pump on a 5.9 Cummins diesel engine is responsible for supplying fuel to the high-pressure fuel pump (HPOP). If the lift pump fails, it can cause the engine to run rough, lose power, or even stall. Testing the lift pump is a relatively simple procedure that can be performed at home with a few basic tools.

In this article, we will walk you through the steps of testing a lift pump on a 5.9 Cummins diesel engine. We will also provide some tips on how to troubleshoot common lift pump problems.

Before you begin, make sure you have the following:

• A fuel pressure gauge
• A 10mm wrench
• A 12mm wrench
• A Phillips head screwdriver
• A flathead screwdriver
• Safety glasses

Step 1: Locate the lift pump

The lift pump is located on the driver’s side of the engine, near the front. It is a small, black cylindrical object with a fuel line connected to it.

Step 2: Disconnect the fuel line from the lift pump

Use a 10mm wrench to loosen the nut on the fuel line that connects to the lift pump. Be careful not to spill any fuel.

Step 3: Connect the fuel pressure gauge to the lift pump

Attach the fuel pressure gauge to the fuel line that was disconnected in step 2. Make sure the gauge is turned off.

Step 4: Start the engine

Start the engine and let it run for a few minutes. The fuel pressure gauge should show a reading of around 50 psi.

Step 5: Turn off the engine

Turn off the engine and disconnect the fuel pressure gauge.

Step 6: Inspect the fuel pressure gauge

The fuel pressure gauge should show a reading of around 50 psi. If the reading is lower than 50 psi, the lift pump is not working properly and will need to be replaced.

Step 7: Troubleshooting

If the lift pump is not working properly, there are a few things you can check to troubleshoot the problem.

• Check the fuel filter. If the fuel filter is clogged, it can restrict the flow of fuel to the lift pump and cause it to fail.
• Check the fuel lines. Make sure the fuel lines are not kinked or damaged.
• Check the fuel injectors. If the fuel injectors are clogged or damaged, they can cause the lift pump to work harder than necessary and eventually fail.

If you have checked all of these things and the lift pump is still not working properly, it will need to be replaced.

How To Test Lift Pump On 5.9 Cummins?

| Step | Action | Expected Result |
|—|—|—|
| 1 | Remove the fuel line from the lift pump. | Fuel should not flow from the line. |
| 2 | Connect a fuel pressure gauge to the lift pump outlet. | The fuel pressure should be between 5 and 10 psi. |
| 3 | Turn on the key and start the engine. | The fuel pressure should increase to 50 psi or more. |
| 4 | Turn off the engine and remove the fuel pressure gauge. | The fuel pressure should drop to zero. |

If the fuel pressure is not within the specified range, the lift pump may be defective and should be replaced.

Identifying the Lift Pump

The lift pump is a small, electric pump that is responsible for supplying fuel to the high-pressure fuel pump (HPOP) on a 5.9 Cummins engine. The lift pump is located on the driver’s side of the engine, near the fuel filter. It is a small, black, cylindrical-shaped object with a fuel line coming out of the top and a electrical connector coming out of the bottom.

The lift pump is a critical component of the fuel system, and if it fails, the engine will not be able to start. Therefore, it is important to be able to identify the lift pump in order to troubleshoot any problems with the fuel system.

To identify the lift pump, follow these steps:

1. Locate the fuel filter on the driver’s side of the engine.
2. The lift pump is located directly above the fuel filter.
3. It is a small, black, cylindrical-shaped object with a fuel line coming out of the top and a electrical connector coming out of the bottom.

Testing the Lift Pump

There are a few different ways to test the lift pump on a 5.9 Cummins engine. The most common method is to use a fuel pressure gauge.

To test the lift pump with a fuel pressure gauge, follow these steps:

1. Remove the fuel line from the lift pump.
2. Connect the fuel pressure gauge to the fuel line.
3. Start the engine and allow it to run for a few minutes.
4. The fuel pressure should be between 5 and 10 psi.

If the fuel pressure is below 5 psi, the lift pump is not working properly and will need to be replaced.

Another way to test the lift pump is to listen for a whining noise. The lift pump should make a whining noise when it is running. If you do not hear a whining noise, the lift pump may be faulty.

Finally, you can also test the lift pump by disconnecting the fuel line from the HPOP. If the engine starts to run rough or stalls, the lift pump is not working properly.

If you suspect that the lift pump is not working properly, it is best to have it tested by a qualified mechanic.

The lift pump is a critical component of the fuel system on a 5.9 Cummins engine. If the lift pump fails, the engine will not be able to start. Therefore, it is important to be able to identify and test the lift pump in order to troubleshoot any problems with the fuel system.

3. Troubleshooting a faulty lift pump

If you suspect that your lift pump is faulty, there are a few things you can check to try and confirm the problem.

• Check the fuel pressure. The fuel pressure should be between 50 and 60 psi at idle. If the pressure is too low, it could be a sign that the lift pump is not working properly.
• Inspect the lift pump for leaks. Look for any signs of fuel leaking from the pump or its connections. If you see any leaks, it could be a sign that the pump is damaged and needs to be replaced.
• Test the lift pump with a multimeter. You can use a multimeter to test the resistance of the lift pump’s windings. If the resistance is too high or low, it could be a sign that the pump is faulty.

If you suspect that your lift pump is faulty, it is best to have it diagnosed and repaired by a qualified diesel mechanic.

4. Replacing the lift pump

Replacing the lift pump on a 5.9 Cummins engine is a relatively straightforward job that can be completed in about an hour. However, it is important to follow the steps carefully to avoid damaging the engine.

Here are the steps involved in replacing the lift pump on a 5.9 Cummins engine:

1. Disconnect the battery. This will prevent any electrical shorts from occurring while you are working on the lift pump.
2. Remove the fuel filter. The fuel filter is located on the top of the lift pump. Disconnect the fuel line from the filter and remove the filter.
3. Remove the lift pump. The lift pump is located on the front of the engine, near the oil filter. There are two bolts that hold the lift pump in place. Remove the bolts and carefully lift the lift pump out of the engine.
4. Install the new lift pump. Align the new lift pump with the mounting holes in the engine. Install the two bolts and tighten them securely.
5. Reconnect the fuel line. Reconnect the fuel line to the new lift pump.
6. Install the fuel filter. Install the new fuel filter.
7. Reconnect the battery.

Once you have replaced the lift pump, start the engine and let it run for a few minutes. Check for any leaks around the lift pump. If you do not see any leaks, the lift pump has been successfully replaced.

The lift pump is an important part of the fuel system on a 5.9 Cummins engine. If the lift pump fails, it can cause a number of problems, including poor fuel economy, engine stalling, and hard starting. If you suspect that your lift pump is faulty, it is best to have it diagnosed and repaired by a qualified diesel mechanic.

Q: How do I test the lift pump on a 5.9 Cummins?

A: To test the lift pump on a 5.9 Cummins, you will need the following tools:

• A multimeter
• A 12-volt test light
• A fuel pressure gauge
• A set of jumper cables

1. Locate the lift pump. The lift pump is located on the driver’s side of the engine, near the front. It is a small, black cylindrical object with a fuel line connected to it.
2. Disconnect the fuel line from the lift pump. Use a wrench to loosen the nut on the end of the fuel line and disconnect it from the lift pump.
3. Attach the fuel pressure gauge to the fuel line. Make sure that the gauge is properly connected to the fuel line and that the needle is at zero.
4. Turn on the key to the ON position. This will activate the fuel pump and send fuel to the lift pump.
5. Check the fuel pressure gauge. The fuel pressure should be between 5 and 10 psi. If the pressure is too low, the lift pump is not working properly and will need to be replaced.
6. Reconnect the fuel line to the lift pump. Use a wrench to tighten the nut on the end of the fuel line and reconnect it to the lift pump.
7. Start the engine. The engine should start and run normally. If the engine does not start or runs rough, the lift pump is not working properly and will need to be replaced.

Q: What are the symptoms of a bad lift pump on a 5.9 Cummins?

A: The symptoms of a bad lift pump on a 5.9 Cummins include:

• The engine starts hard or takes several cranks to start
• The engine runs rough or stalls at idle
• The engine loses power when accelerating
• The check engine light comes on
• There is a whining noise coming from the engine

If you are experiencing any of these symptoms, it is important to have the lift pump checked by a qualified technician as soon as possible.

Q: How much does it cost to replace a lift pump on a 5.9 Cummins?

A: The cost of replacing a lift pump on a 5.9 Cummins can vary depending on the make and model of your truck, the type of lift pump that is installed, and the labor costs at your local repair shop. However, you can expect to pay anywhere from $200 to $500 for the parts and labor.

Q: Can I replace the lift pump myself?

A: It is possible to replace the lift pump on a 5.9 Cummins yourself, but it is a relatively involved job that requires some basic mechanical skills. If you are not comfortable working on your own vehicle, it is best to have the lift pump replaced by a qualified technician.

Q: What are some tips for preventing lift pump failure on a 5.9 Cummins?

A: There are a few things you can do to help prevent lift pump failure on a 5.9 Cummins:

• Use high-quality diesel fuel. Poor quality diesel fuel can damage the lift pump and cause it to fail prematurely.
• Keep the fuel filter clean. A dirty fuel filter can restrict the flow of fuel to the lift pump and cause it to overheat.
• Replace the lift pump at the recommended intervals. The lift pump is a wear item and will eventually need to be replaced. Following the manufacturer’s recommended replacement interval will help to ensure that the lift pump is functioning properly and that your engine is running smoothly.

By following these tips, you can help to prevent lift pump failure on your 5.9 Cummins and keep your truck running smoothly for years to come.

In this blog post, we have discussed how to test the lift pump on a 5.9 Cummins engine. We have covered the following topics:

• The function of the lift pump
• The symptoms of a bad lift pump
• How to test the lift pump with a multimeter
• How to test the lift pump with a pressure gauge

We hope that this information has been helpful. If you have any further questions, please do not hesitate to contact us.