STEP 2: Testing The Fuel Pump's Pressure
Once you have verified that the ignition system is not behind the engine no-start problem, your next step is to check the fuel pump.
As you already know, the fuel pump is responsible for supplying fuel from the tank to the engine.
The fuel pump on the 2.8L V6 Chevy S10 pickup (GMC S15 pickup, GMC Sonoma) is an electric fuel pump and is located in the fuel tank.
As it runs, it pressurizes the fuel in the fuel lines, so it can be delivered to the engine. If the fuel pump is not functioning properly, the engine may not start or run correctly.
By connecting a fuel pressure gauge to the fuel filter using a special adapter, we can easily check the fuel pump pressure and determine if it's working correctly or has malfunctioned.
The following tutorial will walk you through the process of testing the fuel pump pressure by showing you how to connect a fuel pressure gauge to the fuel system and measure the fuel pump's output pressure step-by-step.
The fuel system is NOT causing the no-start problem if:
- Fuel pressure is within 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 also conclude that the fuel pump is not behind the engine's no-start problem.
The next step is to check for a blown head gasket. Go to: STEP 4: 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).
The components that can cause a 0 PSI fuel pressure problem are:
- A bad fuel pump.
- A bad engine oil pressure switch.
- A bad fuel pump relay.
The components that can cause a low fuel pressure problem are:
- A bad fuel pump.
- A bad fuel pressure regulator.
STEP 4: Checking For A Blown Head Gasket
A head gasket is a gasket that sits between the cylinder head and the engine block and the 2.8L V6 engine in your pickup has two.
The head gasket's main function is to seal the combustion chamber, preventing coolant and oil from mixing with the combustion gases.
A blown head gasket can cause the engine not to start in several ways. The most common are:
- Hydro-lock, preventing the engine from turning over due to coolant entering the combustion chamber.
- A head gasket failure between two side-by-side cylinders is causing a loss of compression in both of them. This is because the compression from one cylinder is leaking into the other, and vice versa.
The following tutorial will walk you through the four tests you can perform to check for a blown head gasket:
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
Engine compression plays a critical role in starting the 2.8L V6 internal combustion engine in your Chevy S10 pickup (GMC S15 pickup, GMC Sonoma).
Compression is the process by which the air/fuel mixture is compressed by the movement of the pistons in the cylinders, prior to ignition.
In a nutshell, this is how the process works:
- The starter motor turns the crankshaft, causing the pistons to move upward.
- As the pistons move upward, the air/fuel mixture in the cylinders is compressed.
- The compression in the cylinders reaches a certain level.
- The spark plug generates a spark, which ignites the compressed air/fuel mixture.
- The combustion process starts, creating pressure in the cylinders
- The pressure created by the compressed air/fuel mixture pushes the pistons down.
- The movement of the pistons causes the crankshaft to turn.
- The turning of the crankshaft starts the engine.
A common mistake when trying to troubleshoot an engine that won't start is not checking the engine's compression.
So, if you've already checked the ignition system, fuel pump, and head gaskets and did not find any problems, the next step is to use a compression tester to check the engine's compression.
The following tutorial explains how to perform an engine compression test and interpret the results:
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
As you've seen in this tutorial, to solve an engine no-start issue, it is essential to go through a process of elimination.
This process of elimination includes testing specific components to identify which one is not providing spark, fuel, or causing a lack of compression.
All of the tests can be done with inexpensive tools that can be purchased at your local auto parts store or online.
By doing these tests, you can avoid the frustration and expense of replacing unnecessary parts.
More 2.8L Chevy S10 Pickup, GMC S15 Pickup, And GMC Sonoma Tutorials
You can find a complete list of tutorials for the 2.8L V6 Chevrolet S10 pickup, GMC S15 pickup, and GMC Sonoma in this index:
Here's a sample of the articles, you'll find in the Index of Articles:
- How To Test The Fuel Pump (1988-1993 2.8L Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma).
- How To Test Engine Compression (1988-1993 2.8L Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma).
- How To Test The EGR Valve (1988-1993 2.8L Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma).
- How To Test The Starter Motor (1988-1993 2.8L V6 Chevrolet S10 Pickup, GMC S15 Pickup).
