Testing The Fuel Pump Relay (1997-1999 Chevy/GMC Pick Up And Suburban)

TEST 4: Bench Testing The Fuel Pump Relay

Bench testing the fuel pump relay is pretty easy and in this test section I'll explain the test.

In a nutshell: We'll manually apply battery power and Ground to terminals 85 and 86 of the fuel pump relay with 2 separate jumper wires.

Then we'll check that continuity exists on terminals 30 and 87 (see illustration above) with your multimeter in Ohms mode.

The illustration above (which is a front view of the relay terminals) will help you with your multimeter and jumper wire connections.

These are the test steps:

1. 1

   Connect terminal 85 of the relay to the battery's Ground (-) terminal using a jumper wire with alligator clips.

2. 2

   Connect terminal 86 of the relay to the battery's positive (+) terminal using a jumper wire with alligator clips.

3. 3

   With your multimeter in Ohms mode, probe terminals 30 and 87 (see illustration above).

4. 4

   Your multimeter should show continuity with the relay powered up with the jumper wires.
   
   I don't have an Ohms value to give you, but your multimeter should read anything but the letters OL.

5. 5

   Remove the jumper wires.
   
   Your multimeter should register no-continuity (with the letters OL) on relay terminals 30 and 87.

Let's analyze your fuel pump relay bench test results:

CASE 1: The multimeter showed continuity in the indicated terminals. This is the correct and expected test result and tells you that the relay is functioning correctly.

CASE 2: The multimeter DID NOT show continuity in the indicated terminals. This test result confirms that the relay is defective and needs to be replaced.

Fuel Pump Circuit Diagram

NOTE: The above fuel pump circuit diagram applies to the in-tank fuel pump of the 1997-1999 5.0L and 5.7L Chevy Pick Up and SUV.

More GM 4.3L, 5.0L, and 5.7L Tutorials

You can find a complete list of GM 4.3L, 5.0L, and 5.7L tutorials in this index:

• GM 4.3L, 5.0L, 5.7L Index Of Articles.

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

• How To Test A Misfire / No Spark-No Start Condition (4.3L, 5.0L, 5.7L 96-04).
• How To Clean The GM Mass Air Flow (MAF) Sensor.
• How To Test The Throttle Position Sensor (GM 4.3L, 5.0L, 5.7L).
• How To Test The GM Ignition Control Module (1995-2005).