STEP 2: Testing The Fuel Pump's Pressure
After confirming that an ignition system failure is not behind your engine's no-start problem, the next step is to ensure that the fuel pump supplies fuel to the fuel injectors.
Testing the fuel pump pressure simply involves connecting a fuel pressure test gauge to the Schrader valve located on the fuel injector rail of your 3.4L V6 engine.
You can find the fuel pressure specifications and the fuel pump pressure test explained in a step-by-step manner here: How To Test The Fuel Pump (3.4L V6 Buick, Oldsmobile).
The fuel system is NOT causing the no-start problem if:
- Fuel pressure is within the factory specification.
If the fuel pressure gauge registers the indicated fuel pressure specification, then you can confidently conclude that the fuel pump is working and delivering enough fuel to the fuel injectors.
You can correctly conclude the fuel pump is OK and not behind the engine's no-start problem.
The next step is to check for a blown head gasket. Go to: STEP 3: Checking For A Blown Head Gasket.
The fuel system IS THE CAUSE of the no-start problem if:
- Fuel pressure is 0 PSI (or anything below the fuel pressure specification).
This confirms that the no-start problem is caused by a lack of fuel. This usually means that the fuel pump is bad and needs to be replaced.
STEP 3: Anti-Theft System Checks
The most common failure of the PASS-Key III or Passlock anti-theft system is the PCM (or BCM) not recognizing the key that you're using to crank and start the engine.
When this happens, you'll see one of two problems:
- The engine cranks but does not start. Specifically, the engine starts and runs for a few seconds but then shuts off when the PCM disables the fuel injectors.
- The engine does not crank to start. The PCM has disabled the starter motor (PASS-Key III systems only).
Unfortunately, a PASS-Key III or Passlock failure (that is allowing the engine to crank but not start) can mimic a failed fuel pump problem and usually makes the vehicle owner think that the fuel pump has failed.
Is the anti-theft system the one keeping your vehicle from starting? Here's how you can find out:
A PASS-Key III/Passlock system problem IS behind the no-start problem if the following three conditions are met:
- The fuel pump's pressure is within specification (as confirmed with a fuel pressure test gauge).
- All six spark plug wires are sparking (as confirmed with a dedicated spark tester).
- The engine starts with starting fluid (even though it'll stall after the starting fluid you sprayed into the throttle body gets consumed).
The PASS-Key III/Passlock systems leave specific trouble codes in the PCM or BCM's memory when a failure occurs in one of its components. Unfortunately, you usually need a professional-level scan tool to read these codes.
Vehicles with PASS-KEY III:
- 2002-2005 3.4L Buick Rendezvous.
- 2000-2005 3.4L Oldsmobile Silhouette.
Vehicles with Passlock:
- 1999-2004 3.4L Oldsmobile Alero.
STEP 4: Checking For A Blown Head Gasket
Your 3.4L V6 engine has two head gaskets. When one or both suffer a failure, the engine may not start.
Thankfully testing for a blown head gasket is not difficult, and two of the four tests (to check for blown head gasket) do not require any tools whatsoever.
The following tutorial explains all four tests in a step-by-step manner:
A blown head gasket is NOT causing the no-start problem if:
- The engine oil has a normal color (in other words, it doesn't have a milky-white color).
- The coolant in the radiator remains undisturbed when cranking the engine (with the radiator open).
- The engine passed a block test.
Your next test is to check the engine's compression. Go to: STEP 5: Making Sure The Engine Has Good Compression.
A blown head gasket IS THE CAUSE of the no-start problem if:
- The engine oil has a milky-white color (like coffee with too much creamer).
- - or -
- The coolant in the radiator shot out when cranking the engine (with the radiator open).
- - or -
- The engine failed a block test.
STEP 5: Making Sure The Engine Has Good Compression
The engine compression test is probably one of the most overlooked tests for troubleshooting an engine no-start problem.
It's important to note that this test is usually done after the ignition system and the fuel pump have been eliminated as the causes of the engine no-start problem.
An engine compression problem is NOT causing the no-start problem if:
- The compression of each cylinder is above 120 PSI.
An engine compression problem IS THE CAUSE of the no-start problem if:
- 2 or more cylinders have 0 PSI compression.
- - or -
- All cylinders have 0 PSI compression.
The following tutorial explains how to perform an engine compression test and more importantly, how to interpret your test results:
No-Start Troubleshooting Summary
Troubleshooting the cause of your engine's no-start problem boils down to a process of elimination.
Specifically, you're trying to determine which component keeps the engine from receiving air (compression), fuel, or spark.
By performing some basic tests to confirm the presence of spark, fuel, and compression, you'll save yourself the frustration of replacing components that won't solve the problem.
More 3.4L V6 Buick, Oldsmobile Tutorials
You can find a complete list of 3.4L V6 Buick (Oldsmobile) tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Test Engine Compression Test (3.4L V6 Buick, Oldsmobile).
- How To Test A Blown Head Gasket (3.4L V6 Buick, Oldsmobile).
- What Does The CKP Sensor Do? (3.4L V6 Buick, Oldsmobile).
- How To Test The Throttle Position Sensor (3.4L V6 Buick, Oldsmobile).
If this info saved the day, buy me a beer!
