How To Test The Fuel Pump (2002-2005 GM 2.2L Ecotec)

When the fuel pump fails, your car is not gonna' start. Thankfully, testing the fuel pump on your 2.2L Ecotec equipped GM vehicle is not that hard.

So if you suspect that your car is not starting due to a bad fuel pump, this is the tutorial that'll help you find out (without having to replace the fuel pump first). I'll explain how to do the fuel pump test in a step-by-step way, and what tools you'll need (and where to get them).

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.

You can find this tutorial in Spanish here: Cómo Probar La Bomba De Combustible (2002-2005 2.2L Alero, Cavalier, Grand Am, Sunfire) (at: autotecnico-online.com).

Symptoms Of A Bad Fuel Pump

As you're probably already aware, each of your 2.2L Ecotec's 4 cylinders needs fuel, spark, and air to produce power. When any of these are missing from the mix, your car is going to crank but not start. In other words when you turn the key to start the engine, the engine only turns over but doesn't start.

Here are some more specific symptoms:

1. All of the coil packs, sitting on top of the ignition control module, are creating and delivering spark to the spark plugs. So you know that the ignition system is not at fault.
2. You've sprayed starting fluid (or carburetor spray) into the throttle body and your vehicle 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 2.2L Ecotec engines covered by this tutorial:

TEST 1: Testing Fuel Pressure With A Fuel Pressure Test Gauge

The most accurate way to test the fuel pump on your 2.2L Ecotec equipped GM car is with a fuel pressure test gauge.

The fuel pressure test gauge can be easily connected to your car's fuel system via the Schrader valve on the fuel injector rail. This Schrader valve is very easy to get to and in plain sight on the fuel injector rail.

If you don't own a fuel pressure gauge, you can rent one from your local auto parts store (AutoZone, O'Reilly Auto Parts). If you're interested in buying your own, check out my recommendations here: Where To Buy A Fuel Pressure Test Gauge.

OK, let's get started with this test:

1. 1

   Connect the fuel pressure gauge to the Schrader valve on the fuel 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 cycle the key on and off (but don't start the engine) while you observe the fuel pressure tester's gauge.

3. 3

   Your fuel pressure gauge should register between 53-59 PSI (if the fuel pump is working correctly).
   
   NOTE: The fuel pressure specification of 53-59 PSI is with the key on but engine off (KOEO).

OK, now that the testing part is done, let's take a look at what your results mean:

CASE 1: Fuel pressure test gauge registered 0 PSI or anything under 53-59 PSI. This test result tells you that the fuel pump is not working correctly.

Now, I usually take one more precaution, before condemning the fuel pump as bad and this is to check that the fuel pump is getting 12 Volts as the engine is cranking. This is just to make sure that the fuel pump relay and fuse are OK and doing their job.

What you'll have to do to accomplish this is to attach a multimeter in Volts DC mode to the wire that supplies this voltage to the fuel pump and while a helper cranks the engine, verify that the fuel pump is getting this power. If the 12 Volts are being supplied to the fuel pump then you have now 100% verified that the fuel pump is fried and needs to be replaced.

CASE 2: Fuel pressure test gauge registered between 53-59 PSI. This is the correct and expected test result and tells you that the fuel pump is OK.

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, it's not the most accurate way to troubleshoot a failed fuel pump.

Unfortunately the factory anti-theft system (PASS-Key/Passlock) 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. 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).

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

1. 1

   Remove the intake air duct 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 is a very important safety precaution in case you get a back-fire thru' the intake manifold.

4. 4

   Have your assistant crank the engine once the intake air duct is back on the throttle body.

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 means that the reason your car is not starting is due to a lack of fuel. This will usually be due to one of two things: a bad fuel pump or a problem with your car's anti-theft system (PASS-key/Passlock).

I suggest that your next step be to test the fuel pump's fuel pressure with a test gauge. For this test go to: TEST 1: Testing Fuel Pressure With A Fuel Pressure Test 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 usually means that a lack of fuel IS NOT the reason your car is not starting.

Now, remember what I said about this test not being very accurate? Well, I suggest you do one more test and this is to test the fuel pump's fuel pressure with a test gauge. For this test go to: TEST 1: Testing Fuel Pressure With A Fuel Pressure Test Gauge.

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

One of the most common problems, that will keep your GM car from starting, is a factory anti-theft system failure. If you haven't experienced this problem yet, you'll (it's akin to death and taxes for any GM vehicle owner).

The anti-theft system on your 2.2L Ecotec equipped car is known as the PASS-Key/Passlock system. When an anti-theft system component fails, you car will crank but not start or start momentarily and then die. This no-start condition can seem like it's due to a bad fuel pump.

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

This may lead you to believe that the fuel pump has failed (when it hasn't). To help you tell the difference between a bad fuel pump and an anti-theft system problem take a look at the following chart:

Where To Buy The Fuel Pump And Save

The fuel pump in your 2.2L 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: