The fuel pump in your Chevy S-10 truck supplies fuel to the fuel injection system at a specific volume and pressure. When the fuel system isn't receiving the required fuel, indicated by symptoms including sluggish acceleration and poor fuel mileage, your diagnosis of the problem begins with a fuel pressure test. Testing the fuel pressure on this truck requires a fuel pressure gauge designed for fuel injection testing. The average home mechanic can complete this test in just a few minutes with the right equipment.
Attach the fuel pressure gauge to the fuel pressure test port located on the inlet fuel line. This is the smaller of the two fuel lines, and the test port is located on the driver's side of the engine compartment, near the injectors, in the S-10. Remove the black plastic dust cap and screw the fitting on the end of the gauge hose onto the test port.
Cycle the ignition from the off position to the run position and then to the off position three times. Leave the key in the run position on the last cycle. Read the pressure indicated on the test gauge. On the S-10, it should be 41 to 47 psi with the engine off and the key on.
Start the engine. The pressure should drop slightly to around 35 psi with the engine running and rise slightly when the accelerator is pressed quickly. If the fuel pressure is low, in either test, suspect a faulty fuel pump. If the pressure fails to rise when the accelerator is opened, suspect a faulty fuel pressure regulator.
