Testing Fuel Pressure: 02 Dodge Dakota Guide

If you're experiencing issues with your 02 Dodge Dakota, it could be due to low fuel pressure. Fuel pumps usually fail in one of two ways: a complete failure, where the engine won't start, or a slow death, where the fuel pump still functions but doesn't send enough pressure to the fuel injectors, resulting in engine performance issues. To test the fuel pressure, you'll need a fuel pressure test gauge, which can be purchased online or at your local auto-parts store. The test steps are straightforward: connect the gauge to the Schrader valve on the fuel rail and crank the engine. If the fuel pressure gauge registers 44-54 PSI, your fuel pump is functioning correctly. However, if it reads 0 PSI, it indicates that the fuel pump is not supplying enough fuel for the engine to start.

Symptoms of a bad fuel pump

A bad fuel pump will cause your Dodge Dakota to not start. There are two ways a fuel pump can fail. It will either fail completely and the engine will refuse to start, or it will still function but not send enough fuel pressure and/or volume to the fuel injectors. Here are some symptoms of a bad fuel pump:

• The engine turns over but will not start.
• All 6 spark plug wires are sparking, indicating it's not an ignition system problem.
• The PCM will still pulse all 6 fuel injectors.
• The engine starts after extended cranking.
• Lack of power when accelerating the vehicle.
• Backfires through the intake manifold when accelerating.
• Lean air/fuel mixture trouble codes: P0171 or P0174 or both.
• Intermittent operation, especially when the engine is hot.
• A screeching or whining sound when the engine is engaged.
• A slow or no-start vehicle.
• Engine misfire at highway speeds.
• Hesitant or sluggish acceleration.
• Engine loses power when climbing hills or pulling trailers.
• Lower fuel efficiency.

Where to buy a fuel pressure test gauge

To test the fuel pump on your 2002 Dodge Dakota, you will need a fuel pressure test gauge. These can be purchased from a variety of places, including online retailers and local auto-parts stores.

Online Retailers:

• Amazon: A wide variety of fuel pressure test kits are available on Amazon, with prices ranging from around $20 to $500. Some popular options include the BETOOLL Fuel Pressure Test Kit, the Orion Motor Tech Fuel Pressure Gauge, and the Innova Fuel Injection Pressure Tester.
• Bosch Diagnostics: They offer a fuel pressure tester kit that is designed to work with most domestic fuel-injected vehicles with a Schrader valve test port on the fuel rail. This includes Ford, GM, Chrysler, and others.

Local Auto-Parts Stores:

• AutoZone: AutoZone offers a range of fuel pressure test kits, including the Innova Fuel Injection Pressure Tester and the OEMTOOLS Fuel Pressure Test Kit. They also provide adapters for vehicles that don't have the right valve.
• Local auto-parts stores: In addition to AutoZone, there are other local auto-parts stores that may carry fuel pressure test gauges, such as Advance Auto Parts, O'Reilly Auto Parts, or NAPA Auto Parts.

Other Options:

• Borrow from a friend: If you have a friend or family member who is a DIY enthusiast or mechanic, they may have a fuel pressure test gauge that you can borrow.
• Rent from a local garage: Some local garages or repair shops may be willing to rent out or loan a fuel pressure test gauge for a small fee.

It is important to ensure that the fuel pressure test gauge you purchase or borrow is compatible with your 2002 Dodge Dakota. Additionally, always exercise caution when working with fuel and pressure systems, as gasoline is highly flammable.

Using starting fluid to confirm lack of fuel

Using starting fluid to confirm a lack of fuel is a common test performed to check if a lack of fuel is causing a no-start problem. Although it is not the most accurate method, it is still effective and will get your fuel pump diagnostic started.

Note: To get an accurate test result from the starting fluid test, ensure that all six spark plug wires are sparking.

Safety Precaution: This test is fast and easy but remember to reconnect the air intake duct back to the throttle body after spraying starting fluid down the throttle bore. This will prevent any backfire that might occur when cranking the engine.

Step 1: Remove the intake air duct from the throttle body. You don't have to remove it completely, as you will need to reconnect it in the next step.

Step 2: Open the throttle plate and spray starting fluid down the bore. As a safety precaution, reconnect the air duct after you have sprayed a good squirt of starting fluid. You don't need to tighten the air duct.

Step 3: Crank the engine once the air duct is back on and you're clear of the engine compartment.

You will get one of two results with this test:

• The engine starts momentarily and then dies: This test result confirms that a lack of fuel is keeping your Dodge Dakota's engine from starting. Your next step is to check the fuel pressure with a fuel pressure test gauge.
• The engine does not start at all: This usually means that a lack of fuel is not the reason your car is not starting. However, as this test is not very accurate, you may want to perform another test to check the fuel pressure with a fuel pressure test gauge.

Checking fuel pressure with a fuel pressure gauge

Step 1: Prepare the Necessary Tools

You will need a fuel pressure test gauge to perform this test. There are several fuel pressure test gauge kits available online or at your local auto parts store that will work with your Dodge Dakota, such as the Actron CP7818 Fuel Pressure Tester Kit, Actron CP7838 Professional Fuel Pressure Tester, or OTC 5630 Fuel Pressure Test Kit. These kits come with the fitting that connects to your Dodge's Schrader valve.

Step 2: Locate the Schrader Valve

The Schrader valve is located on the fuel injector rail of your Dodge Dakota. This is where you will connect the fuel pressure gauge.

Step 3: Prepare the Test Area

Place a shop towel around the Schrader valve to absorb any fuel that may leak during the test.

Step 4: Connect the Fuel Pressure Gauge

Connect the fuel pressure gauge to the Schrader valve on the fuel injector rail. Ensure that the connection is secure and tight to prevent fuel leaks.

Step 5: Crank the Engine

Ask your helper to cycle the key ON and OFF without cranking the engine while you observe the fuel pressure tester's gauge. This will give you a baseline reading.

Step 6: Check for Fuel Leaks

If you notice any fuel leaks at the connection, tighten the fuel pressure gauge slightly by hand to eliminate the leaks.

Step 7: Start the Engine

Crank and start the engine, and check the fuel pressure gauge. For a 2000, 2001, or 2002 3.9L Dodge Dakota, the fuel pressure gauge should register between 44-54 PSI. For a 2003 3.9L Dodge Dakota, the fuel pressure should be between 47-51 PSI.

Step 8: Interpret the Results

If the engine doesn't start, crank the engine enough to get the fuel pressure up and observe the fuel pressure gauge again. Here's what your results could mean:

• Case 1: 0 PSI - This indicates that the no-start problem is caused by a lack of fuel from the fuel pump. Before condemning the fuel pump as bad, you should also check that the fuel pump is receiving 12 Volts as the engine is cranking to ensure that the fuel pump relay and fuse are functioning properly.
• Case 2: Indicated PSI - This is the correct test result. It means that the fuel pump is working properly and delivering enough fuel to the fuel injectors. The no-start issue is likely due to another reason, and the fuel pump is not the cause.

By following these steps and interpreting the results, you can effectively test the fuel pressure in your 2000-2003 3.9L Dodge Dakota using a fuel pressure gauge.

What to do if the fuel pump is bad

If your fuel pump is bad, you will likely experience major performance issues with your vehicle. Here are some common signs of a failing or failed fuel pump:

• The car won't start or struggles to start: This could be due to a lack of fuel reaching the engine, which is often caused by a faulty fuel pump that cannot deliver enough fuel to start the engine.
• The car sputters or dies while driving: A faulty fuel pump may cause the engine to sputter and stall, especially when the vehicle is accelerating or under stress, such as towing a heavy load or driving uphill.
• The engine surges: If the fuel pump is sending too much fuel to the engine, you may experience speed spikes and drops, even when you haven't touched the gas pedal or brake.
• Excessive whining noise from the fuel pump: A failing fuel pump may emit a loud, whining noise, indicating that it is struggling and about to fail.
• Lower fuel efficiency: A bad fuel pump can lead to poor fuel efficiency as it may allow excess fuel into the engine, resulting in more frequent trips to the gas station.
• Loss of power: If you notice a decrease in power when driving up steep inclines or carrying cargo, it could be due to a faulty fuel pump that is unable to provide enough fuel to the engine under stress.

If you suspect that your fuel pump is bad, it is important to have it inspected by a qualified technician to confirm the issue and recommend the necessary repairs or replacements.

Frequently asked questions