TEST 2: Making Sure The EVAP Solenoid Is Blocking Fuel Vapor Intake
The EVAP purge solenoid, when not commanded ON by the fuel injection computer, is in its OFF state ('closed' state).
In this OFF state, it blocks fuel vapor from passing thru' to the intake manifold.
In this test section, we're gonna' remove it and make sure that the EVAP purge solenoid is in its closed state by blowing air thru' it.
Let's get testing:
- 1
Disconnect the plastic line that connects the EVAP purge solenoid's fuel vapor inlet port.
This plastic line is the one that connects the EVAP purge solenoid to the carbon canister. - 2
Disconnect the EVAP purge solenoid from its connector.
- 3
Remove the EVAP purge solenoid from its place.
This is done by removing the bolt from the solenoid's mounting bracket. - 4
Blow air into the purge solenoid's fuel vapor inlet port (see photo above).
I usually use a clean piece of rubber fuel/vacuum hose over the inlet port and my mouth for this step. - 5
Air should NOT pass thru' the EVAP purge solenoid.
Let's take a look at what your test results mean:
CASE 1: Air DID NOT pass thru' the EVAP purge solenoid. This is the correct and expected test result.
The next step is to bench-test the EVAP purge solenoid and see if it 'opens'. For this test go to: TEST 3: Bench Testing The EVAP Purge Solenoid.
CASE 2: Air passed thru' the EVAP purge solenoid. This result tells you that the EVAP purge solenoid is bad and is stuck in its 'open' state.
Replace the EVAP purge solenoid to solve the P0443 trouble code lighting up the check engine light.
TEST 3: Bench Testing The EVAP Purge Solenoid
For our 3rd and last test, we're gonna' make sure that the EVAP purge solenoid 'opens' and lets air pass thru' when we apply battery 12 Volts and Ground to it.
To perform this test safely, it's important that you use jumper wires with insulated alligator clips, or you run the risk of frying the solenoid if the jumper wires short-circuit to each other.
Once the EVAP purge solenoid is powered ON, it should let air pass thru' it. If it doesn't, then we can conclude that it's bad and needs to be replaced.
OK, these are the test steps:
- 1
Connect the red insulated jumper wire to the male terminal labeled with the letter A in the photo above.
- 2
Connect the other end of the red insulated jumper wire to the battery positive (+) terminal.
- 3
Connect the insulated black jumper wire to the male terminal labeled with the letter B.
- 4
Connect the other end of the black insulated jumper wire to the battery negative (-) terminal.
- 5
The EVAP solenoid should make a 'click' sound as soon as you apply Ground to it.
With 12 Volts and Ground applied to the EVAP purge solenoid, the solenoid should be 'open' and should allow air to pass thru' it. - 6
Blow air into the vapor inlet port of the solenoid (you can use your mouth) to make sure that the solenoid has opened and is allowing air to pass thru' it.
Let's take a look at what your test results mean:
CASE 1: The EVAP purge solenoid activated and allowed air to pass thru' it. This is the correct and expected test result.
You can conclude that the EVAP purge solenoid is good if you have:
- Confirmed that the EVAP solenoid is getting 10 to 12 Volts (TEST 1).
- Confirmed that you CAN NOT blow air thru' the EVAP purge solenoid in its OFF state (TEST 2).
- Confirmed in this test section that the EVAP purge solenoid opens and allows air to pass thru' it (when you applied 12 Volts and Ground to it).
CASE 2: The EVAP purge solenoid activated but DID NOT allow air to pass thru' it. This test result lets you know that the EVAP purge solenoid is bad and needs to be replaced.
CASE 3: The EVAP purge solenoid DID NOT activate and DID NOT air to pass thru' it. This test result lets you know that the EVAP purge solenoid is bad and needs to be replaced.
More Chevrolet Silverado (GMC Sierra) Tutorials
You can find a complete list of V8 Chevrolet Silverado (GMC Sierra) tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- Resistance Specifications Of The TAC Electronic Throttle Body.
- How To Test The GM Accelerator Pedal Position (APP) Sensor 2.
- How To Test The MAF Sensor (GM 4.8L, 5.3L, 6.0L, 8.1L).
- Blown Head Gasket Test (GM 4.8L, 5.3L, 6.0L).
If this info saved the day, buy me a beer!
