How To Test The Fuel Pump (1994-1999 2.0L SOHC Dodge/Plymouth Neon)

Sooner or later, the fuel pump in your 1995-1999 2.0L Neon will fail. If you suspect it's having issues, I can tell you that testing it is quite easy. In this tutorial, you'll find the information you need to test it!

I'm also including instructions on how to test a 'cranks but does not start' issue, to see if it's caused by a lack of fuel, with starting fluid.

NOTE: This tutorial applies only to the 2.0L SOHC engine (Single Overhead Camshaft).

You can find this tutorial in Spanish here: Cómo Probar La Bomba De Combustible (1994-1999 2.0L SOHC Dodge/Plymouth Neon) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 2.0L Dodge Neon: 1995, 1996, 1997, 1998, 1999.
• 2.0L Plymouth Neon: 1995, 1996, 1997, 1998, 1999.

2000-2005 FUEL PUMP PRESSURE TEST: You can find the fuel pump pressure test procedure for the 2000-2005 2.0L Dodge/Plymouth Neon here:

• How To Test The Fuel Pump (2000-2005 2.0L SOHC Dodge/Plymouth Neon).

IMPORTANT: Gasoline is extremely flammable. Be careful and take all necessary safety precautions. Be careful when using a starting fluid, as it ignites as easily as gasoline. You can successfully perform both tests without any issues if you proceed with care. Also, make sure to perform all tests with a cooled down engine, work in a well-ventilated area, and stay away from open flames or sparks.

Symptoms Of A Bad Fuel Pump

Fuel pumps often fail in one of two ways:

• Complete failure: The engine cranks but doesn't start.
• Slow failure: the engine starts and runs but experiences performance issues, especially under load.

To be a bit more specific, here are some of the symptoms you'll see from a complete fuel pump failure:

• The engine cranks but doesn't start.
• No fuel pressure is detected.
• No noise from the fuel pump.

These are some of the symptoms of a slow fuel pump failure:

• Lack of power when accelerating the engine under load.
• Unexplained loss of power.
• Bad gas mileage.
• The engine suddenly stalls.

Whether the fuel pump is failing or has failed, a fuel pressure test with a fuel pressure gauge will help you identify the cause of the problem. Not only that, but this simple test will simplify your fuel pump diagnostic, meaning you'll spend less time (and less frustration) solving the issue and be able to replace the right part.

Where to Buy a Fuel Pressure Gauge

One of the most important tools that anyone working on their own vehicle should have in their toolbox is a fuel pressure gauge. The good news is that you can buy them at almost any auto parts store and online.

The following fuel pressure test kits are very good deals and will connect to the vehicles included in this tutorial:

Fuel Pressure Specifications

• KOEO = Key On Engine Off.
• KOER = Key On Engine Running.

Fuel Pressure Test With A Gauge

The 1994-1999 Dodge and Plymouth Neon SOHC engine comes equipped with a fuel pressure test port (Schrader valve) on the fuel injector rail. In the photo above, the orange arrow points to the Schrader valve where you'll connect your fuel pressure gauge.

According to the factory repair manual, you need a scanner to activate the fuel pump and check its pressure output with the key on and the engine off, which is great if you have one.

For the rest of us without one, here's the alternative: if the engine starts, simply disconnect the electrical connectors from the fuel injectors and crank the engine. It's the same procedure if the engine does not start. The following steps assume you're not using a scan tool to activate the fuel pump and check the pressure.

OK, these are the test steps:

1. 1

   Disconnect the four fuel injectors from their electrical connectors.
   
   NOTE: This step only applies if the engine starts and runs.

2. 2

   Remove the dust cap from the Schrader valve on the fuel injector rail.

3. 3

   Place a towel under the area of the Schrader valve.

4. 4

   Connect the fuel pressure gauge to the Schrader valve.
   
   Use a towel to dry any fuel that may have been released during the gauge connection process.

5. 5

   When you're ready, have your assistant crank the engine while you observe the pressure gauge.

6. 6

   The gauge should display the specified fuel pressure.

Let's take a look at what your results mean:

CASE 1: The fuel pump pressure is within specification. This indicates that the fuel pump is in good working condition and supplying fuel to the injectors.

If your Neon's engine doesn't start, then this test result rules out the fuel pump as the source of the engine's 'cranks but does not start' issue.

CASE 2: The fuel pump pressure is NOT within specification. This result tells you that the fuel pump is not functioning. Since the fuel pump isn't working, you can now conclude that it's behind the 'cranks but does not start' issue of your Neon.

Using Starting Fluid To Check For A Lack Of Fuel

The starting fluid test is one of the first tests I learned when I began my automotive repair career. Although it's not the most precise way to test the fuel pump, it will let you know if the engine isn't starting due to a lack of fuel (like when the fuel pump fails).

Another important thing you should know about this test is that you first need to check that all four cylinders have spark. You can easily find out by testing each spark plug wire for spark (as a helper cranks the engine). Once you've verified that all cylinders have spark, you'll be ready for the starting fluid test.

OK, here are the test steps:

1. 1

   Remove the intake air duct from the throttle body.
   
   You don't have to remove it completely as you'll need to reconnect it in one of the following steps.

2. 2

   Manually open the throttle plate and spray starting fluid into the throttle body bore.

3. 3

   Quickly reconnect the air duct to the throttle body (no need to tighten the hose clamp).
   
   NOTE: Reconnecting the intake air duct is a very important safety precaution in case of backfire through the intake manifold.

4. 4

   Crank the engine once the intake air duct is back on the throttle body.

5. 5

   You'll get one of two results:
   
   1.) The engine will briefly start, run and then shut off after a few seconds.
   
   2.) The engine cranks but doesn't start at all.

Alright, let's figure out what it all means:

CASE 1: The engine started and ran for a few seconds. This confirms that the issue of your vehicle cranking but not starting is due to a lack of fuel.

I suggest your next step should be testing the fuel pump pressure with a pressure gauge. For this test, go to: Fuel Pressure Test With A Gauge.

CASE 2: The engine did NOT start, not even briefly. This indicates that a lack of fuel is not the reason why the engine won't start.