STEP 2: Testing The Fuel Pump's Pressure
After you've confirmed that all six spark plugs are sparking (and thus confirming that the ignition system is not behind the no-start problem), the next step is to make sure the fuel pump is supplying the engine with gasoline.
The most accurate way of testing the fuel pump is with a fuel pressure test gauge.
This fuel pressure test gauge is connected to the fuel system with an adapter. This adapter is connected between the fuel injector rail and the fuel pressure line.
The fuel pump pressure specification for the 1989-1993 3.3L V6 Buick and Oldsmobile vehicles is:
- 40-47 PSI Key On With Engine Off.
- With Key On Engine Running, fuel pressure should drop 3 to 10 PSI.
You can find the fuel pump pressure test explained in a step-by-step manner here: How To Test The Fuel Pump (3.3L V6 Buick, Oldsmobile).
The fuel system is NOT causing the no-start problem if:
- Fuel pressure is within the 40 to 47 PSI range.
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: Checking For A Blown Head Gasket
A blown head gasket, and your 3.3L engine has 2 head gaskets, will definitely keep the engine from starting.
In the majority of cases, a blown head gasket is usually caused by severe engine overheating.
There are 4 specific tests to check for a blown head gasket and you can find them explained in this tutorial:
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 4: 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 4: Making Sure The Engine Has Good Compression
As mentioned earlier, air is one of the three things the engine needs to start. This 'air' refers to the compression produced by the engine's pistons.
If you have eliminated the ignition system, the fuel pump, and a blown head gasket as the cause of your 3.3L V6 Buick or Oldsmobile's no-start problem, then the next step is to test the engine's compression.
I've written a detailed ‘how to test the engine compression’ tutorial, and you can find it here:
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.
No-Start Troubleshooting Summary
The most important thing to remember when diagnosing an engine no-start problem, is that the engine needs 3 things to be able to start.
These 3 things are:
- Spark.
- Fuel.
- Air (compression).
When the engine does not start, it's because one of these is missing from the mix.
Therefore, testing an engine no-start problem literally boils down to a process of elimination.
Once you've confirmed that you've got spark at all cylinders, there isn't any need to spend time testing the ignition system. The next step is to make sure the fuel pump is working and so on and so on.
By checking these basic things (spark, fuel, air), you'll save yourself the frustration of replacing components that won't solve the problem.
More 3.3L V6 Buick, Oldsmobile Tutorials
You can find a complete list of 3.3L 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 (3.3L V6 Buick, Oldsmobile).
- How To Test A Blown Head Gasket (3.3L V6 Buick, Oldsmobile).
- How To Test The MAF Sensor (3.3L V6 Buick, Oldsmobile).
- What Does A MAF Sensor Do? (3.3L V6 Buick, Oldsmobile).
If this info saved the day, buy me a beer!
