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 seperate 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:
Connect terminal 85 of the relay to the battery's Ground (-) terminal using a jumper wire with alligator clips.
Connect terminal 86 of the relay to the battery's positive (+) terminal using a jumper wire with alligator clips.
With your multimeter in Ohms mode, probe terminals 30 and 87 (see illustration above).
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.
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.
Where To Buy The Fuel Pump Relay
The following links will help you comparison shop for the fuel pump relay:
Not sure if the above fuel pump relay fits your particular Chevrolet/GMC pick up or SUV? Don't worry, once you arrive on the site, they'll make sure it fits! If it doesn't, they'll find you the right one.
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:
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).
If this info really saved the day, buy me a beer!