How To Test The Fuel Pump (1992-1995 4.3L CPI Chevrolet S10 Pickup, GMC Sonoma)

The Starting Fluid Test

How To Test The Fuel Pump With Starting Fluid (1992, 1993, 1994, 1995 4.3L V6 CPI Chevrolet S10 Pickup And GMC Sonoma)

Starting fluid can be used to check if a lack of fuel is preventing the engine from starting (for example, lack of fuel due to a faulty fuel pump).

If a lack of fuel is causing the engine's no-start problem, the starting fluid will cause the engine to start and run for a few seconds.

If the engine's no-start problem is NOT due to lack of fuel, the starting fluid will have no effect.

While using starting fluid to test a fuel pump is not the most accurate method, it will point your troubleshooting efforts in the right direction.

The most important thing to remember when performing a starting fluid test is that you first need to make sure that all six spark plug wires are sparking (with a spark tester).

IMPORTANT: If you haven't checked all six spark plug wires for spark yet, please do so before performing the starting fluid test. I recommend using a dedicated spark tester for the spark test.

OK, these are the test steps:

  1. 1

    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.

  2. 2

    Open the throttle manually, and spray starting fluid down the bore.

  3. 3

    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 a very important safety precaution in case you get a back-fire thru' the intake manifold.

  4. 4

    Crank the engine once the intake air duct is back on the throttle body.

  5. 5

    You'll get one of two results with this test:

    1.) The engine will start momentarily and after a few seconds will die.

    2.) The engine will only crank but not start at all.

OK, let's interpret your test results:

CASE 1: The engine started and ran for a few seconds. This test result confirms that the engine isn't starting due to a lack of fuel.

The most likely cause of this lack of fuel is a bad fuel pump.

CASE 2: The engine did not start, not even momentarily. This test result tells you that the engine's no-start problem IS NOT due to a lack of fuel.

It's important to note that this the accuracy of this test result depends on having all six spark plug wires sparking.

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Chevrolet Vehicles:

  • S10 Pickup 4.3L
    • 1992, 1993, 1994, 1995

GMC Vehicles:

  • Sonoma 4.3L
    • 1992, 1993, 1994, 1995