I'm going to show you two different methods to verify if the no start condition on your 3.1L or 3.4L GM vehicle is due to a lack of fuel, which usually means that the fuel pump has gone bad.
One method involves using just starting fluid and the other involves using a fuel pressure gauge. One method is a very accurate way of diagnosing a lack of fuel condition causing a no start. The other method is not that accurate.
I've used both methods successfully and I'll describe them in a step-by-step way in this tutorial.
Contents of this tutorial:
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 (GM 3.1L, 3.4L) (at: autotecnico-online.com).
Symptoms Of A Bad Fuel Pump
A bad fuel pump will make your 3.1L or 3.4L Venture (or Malibu, Regal, Skylark, Corsica, Impala, Venture, etc.) crank but not start. Here are some more specific symptoms:
- 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.
- 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.
FUEL PUMP TEST 1: Using Starting Fluid
Checking to see if your car (or mini-van starts) with a good dose of starting fluid is the most common way to get the ‘ball rolling’ when troubleshooting a bad fuel pump.
Using starting fluid is not the most accurate way of testing the fuel pump but it doesn't mean it's not effective.
I've used this starting fluid test with good success, along with a few other tests, to verify if the vehicle I'm working on is not starting because no fuel is reaching the engine.
OK, to get this show on the road, this is what you'll need to do:
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.
Open the throttle, manually, and spray starting fluid down the bore. When you have sprayed a good squirt of starting fluid, quickly reconnect the air duct to the throttle body (you don't have to tighten the hose clamp).
Reconnecting the intake air duct is important because your 3.1L or 3.4L Malibu (Venture, Monte Carlo, Grand Am, Century, Regal, etc) may be equipped with a MAF sensor. Also, it's a very important safety precaution in case you get a back-fire thru' the intake.
Once the intake air duct is back on the throttle body, have your assistant, inside the vehicle, crank the engine.
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 Skylark (or Impala, Lumina, Monte Carlo, Achieva, Alero, etc.) is not starting is due to a lack of fuel.
Usually, this also means that the fuel pump is bad. But since we don't live in a perfect world, this could also mean a few other things like: the fuel pump fuse is blown, or the fuel pump relay is bad. Now, don't worry about this too much, because you can test this by:
- Removing the fuel line that connects to the fuel injector rail (this is the one that delivers fuel from the fuel filter) and place it in a container. When ready, have your helper bump the starter motor while you verify if fuel comes out or not. No fuel coming out of the fuel line further confirms a bad fuel pump.
- Making sure that the fuel pump is getting power (12 Volts) when you crank the engine. How? By tapping into the wire that feeds the pump power and making sure it's feeding the pump with 10 to 12 Volts when your helper is cranking the engine.
NOTE: There's a good chance that anti-theft system on your vehicle is behind the no start problem. For more info, 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.
This is to remove the fuel line that connects to the fuel injector rail and place it in a container. Then have a helper bump the starter while you check to see if fuel comes out of the Line and into the container. This way, you can visually see if there is or there isn't fuel coming out of the fuel line.
A no start condition can be caused by a number of things (yeah, I know, life's a bitch), so my recommendation is to see take a look at this tutorial: How To Troubleshoot A No Start (GM 3.1L, 3.4L).