How To Test The Fuel Pump (2008-2010 GM 2.4L Ecotec)

Quite a few things can cause your car to not start and a failed fuel pump is one of them. The cool thing is that you can easily and quickly check the fuel pump (to see if it's bad or not).

Why? Because GM has installed a Schrader valve on the fuel injector rail that facilitates checking the fuel pump with a fuel pressure test gauge.

Don't worry, a fuel pressure test gauge is not inexpensive diagnostic tool and you can pretty much find one (to buy) just about anywhere (AutoZone, Pepboy's, O'Reilly Auto Parts, etc). If you don't have one, I'm going to show you where you can buy one and save a few bucks in the process.

IMPORTANT: Gasoline is extremely flammable. Be careful and take all necessary safety precautions. Use extreme care when using starting fluid since it ignites as easily as gasoline. Accomplishing both tests indicated in this article, without any unhappy consequences, is more than possible if you're careful and use common sense.

Symptoms Of A Bad Fuel Pump

A bad fuel pump will make your 2.4L Ecotec equipped vehicle crank but not start. Here are some more specific symptoms:

1. All four ignition coils, sitting on top of the valve cover, are creating and delivering spark to the spark plugs. This tells you that the no-start problem is NOT due to an ignition system problem.
2. You've sprayed starting fluid (or carburetor spray) into the throttle body and the engine started, even if only momentarily.

Although the above list is a not a very complete list of symptoms, the theme that runs thru' them, and any other related symptom, is that the engine will crank and crank, but not start.

Where To Buy A Fuel Pressure Test Gauge

One of the most important tools any serious DIY'er should have in his/her tool box is a fuel pressure test gauge. The cool thing is that you can buy them in just about any auto parts store (although at a higher price).

The following fuel pressure test gauge kits are pretty good deals and will connect to the 2.4L Ecotec engines covered by this tutorial:

FUEL PUMP TEST 1: Fuel Pressure Test With Gauge

It used to be that fuel pressure gauges were expensive and out of the reach of the serious DIY'er. But times have changed and fuel pressure test gauges have come down a lot in price.

This is good news for you and I since it allows us to accurately test the fuel pump to see if it has failed (or not).

Fuel pressure test gauges are such a 'must have' tool that you can even borrow one from your local auto parts store if you don't own a fuel pressure test gauge.

If you're interested in buying your own and saving a few dollars in the process, check out my recommendations here: Where To Buy A Fuel Pressure Gauge.

OK, let's get started with this test:

1. 1

   Connect the fuel pressure gauge to the Schrader valve on the fuel injector rail.
   
   With a shop towel, mop up any fuel that was released during the process of connecting the fuel pressure test gauge.

2. 2

   When ready, ask your helper to crank the engine while you observe the fuel pressure tester's gauge.

3. 3

   Your fuel pressure gauge should register 50-60 PSI as your helper is cranking the engine.

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

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

If your 2.4L Ecotec equipped vehicle is not starting, then this test result has now eliminated the fuel pump as the source of the problem. There's a good chance that the anti-theft system on your vehicle is causing the no-start problem. I suggest you take a look at the phone section Is The Anti-Theft System Causing The No Start Condition?

CASE 2: The fuel pump pressure IS NOT within specification. This test result tells you that the fuel pump is not working. Since the fuel pump is not working, you can now conclude that it's behind your 2.4L Ecotec engine's no-start problem.

FUEL PUMP TEST 2: Using Starting Fluid

Using starting fluid, to confirm a lack of fuel condition causing a no-start problem, is a very old troubleshooting technique. But, using it to check for bad fuel pump on your GM vehicle (which is equipped with the Passlock Anti-Theft System) still requires that you check the fuel pump with a fuel pressure gauge.

Yep, I hate to say this but your vehicle's factory anti-theft system complicates the result of the starting fluid test. This is due to the fact that the factory anti-theft system (Theft Deterrent System) on your car can mimic a failed fuel pump.

The starting fluid test won't be able to tell you whether the lack of fuel problem is caused by an anti-theft system problem or a bad fuel pump. So, to repeat myself, this means that you still have to do a fuel pressure test (to check the fuel pump).

The starting fluid test still has its merits. Because it is a good way verify if the no-start problem is due to a lack of fuel condition (either due to a bad fuel pump or an anti-theft problem). But if you want a faster and accurate fuel pump test result, start with: FUEL PUMP TEST 1: Fuel Pressure Test With Gauge.

OK, to get this show on the road, this is what you'll need to do:

1. 1

   Remove the intake air duct assembly from the throttle body.
   
   You don't have to completely remove it, since you'll have to reconnect it in one of the next steps.

2. 2

   Open the throttle, manually, and spray starting fluid down the bore.

3. 3

   Quickly reconnect the air duct to the throttle body (you don't have to tighten the hose clamp).
   
   Reconnecting the intake air duct assembly is important because your 2.4L Ecotec equipped vehicle is equipped with a MAF sensor. Also, it's a very important safety precaution in case you get a back-fire thru' the intake.

4. 4

   Have your assistant crank the engine while you observe the gauge.

5. 5

   You'll get one of two results with this test:
   
   1.) The engine will start momentarily and after a few seconds will die or.
   
   2.) The engine will only crank but not start at all.

OK, let's find out what your results mean:

CASE 1: If the engine started and ran for a few seconds. This confirms that your vehicle's no-start problem is due to a lack of fuel. The only problem is that this could be due to either an anti-theft system component failure or a bad fuel pump.

I suggest that your next step be to test the fuel pump's fuel pressure with a test gauge. For this test go to: FUEL PUMP TEST 1: Fuel Pressure Test With Gauge.

For more info about an anti-theft system failure go to: Is The Anti-Theft System Causing The No-Start Condition?

CASE 2: The engine did not start, not even momentarily. This test result is very inconclusive. So, your next step is to check the fuel pump pressure with a test gauge. For this test go to: FUEL PUMP TEST 1: Fuel Pressure Test With Gauge.

Is The Anti-Theft System Causing The No Start Condition?

Your vehicle comes equipped with a factory anti-theft system. This system is very, very problem prone as the car ages. Eventually, the anti-theft system will cause your car to crank but not start.

When this happens, the resulting no-start problem will make you think that the fuel pump has failed. Yep, that's right, the anti-theft system failure usually mimics a failed fuel pump.

To explain this a bit further, the anti-theft system is designed to disable the fuel injectors (when it activates) 3 seconds after the engine starts. So if you use starting fluid (while the engine is being cranked), the engine will start (and of course die when the dose of starting fluid you just sprayed gets consumed).

The following chart should help you figure out if the anti theft system is one behind your engine's no-start problem:

Where To Buy The Fuel Pump And Save

The fuel pump in your 2.4L Ecotec equipped GM car is located inside the fuel tank. The fuel pump can be bought in any auto parts store, but I think you'll find the better price online. The following fuel pumps are pretty good deals: