How To Test The Fuel Pump (1987-1993 2.5L Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma)

The Starting Fluid Test

Starting fluid can be used to determine if a lack of fuel is causing an engine no-start problem.

I've used starting fluid to diagnose the cause of many engine no-start problems over the years and I can tell you this test works.

While the starting fluid test is not the most accurate way to diagnose a bad fuel pump, it will steer your troubleshooting efforts in the right direction.

OK, let's begin:

1. 1

   Remove the cover from the air cleaner assembly.
   
   You don't have remove the air cleaner assembly from the engine (best to leave it in place).

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 install the air cleaner assembly's cover (you don't have to tighten the nut).
   
   Reinstalling the air cleaner assembly's top is a very important safety precaution in case you get a back-fire thru' the intake manifold.

4. 4

   Crank the engine once you've place the cover back on the air cleaner assembly.

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.

More 2.5L Chevy S10 Pickup, GMC S15 Pickup, And GMC Sonoma Tutorials

You can find a complete list of 2.5L Chevy S10 pickup, GMC S15 pickup, And GMC Sonoma tutorials here:

• S10, S15, Sonoma 2.5L Index of Articles.

Here's a sample of the tutorials you'll find in the index:

• How To Test Engine Compression (1985-1993 2.5L Chevrolet S10, GMC S15, GMC Sonoma).
• How To Test For A Blown Head Gasket (1985-1993 2.5L Chevrolet S10, GMC S15, GMC Sonoma).
• How To Test The TPS (1987-1993 2.5L Chevrolet S10, GMC S15, GMC Sonoma).
• How To Test The MAP Sensor (1985-1993 2.5L Chevrolet S10, GMC S15, GMC Sonoma).