Repairing Ford evaporative system leak
This bulletin involves DTC P0456 on 2007-2008 Ford E-150, E-250, E-350 and Expedition F-150; and 2007-2008 Lincoln Mark LT and Navigator.
ISSUE: Some of these vehicles may exhibit a MIL-on with DTC P0456 (very small evaporative system leak….0.020 in. in diameter).
Perform the following diagnostic steps when this DTC is found in memory. The procedure requires validation of the evaporative system leak size before attempts are made to locate and repair the leak. Use of a Vacutec leak machine or equivalent machine is required for this procedure.
NOTE: Currently the IDS EVAP leak measurement tool is not capable of measuring leaks less than 0.035 in. in diameter. IDS cannot be used to measure leak size or validate repair for DTC P0456.
Many EVAP leaks are caused by a loose or damaged fuel cap. If the fuel cap is suspected during a visual inspection, do not disturb the cap until the leak verification pressure test is completed.
Before attempting to locate or repair leaks, first verify leak size using a Vacutec machine.
Prepare the vehicle for hook-up to the Rotunda Vacutec or equivalent machine.
When using the Vacutec machine, the fuel level in the tank must be greater than 15% and less than 85%.
Connect the Vacutec machine power cables to the vehicle battery. Check to see that the Vacutec power indicator lamp is on, indicating good battery contact. Disconnect the fuel vapor to intake manifold line at the electrical vapor management valve (eVMV) and cap the line. Connect a 5/16-inch ID flexible vinyl clear hose with a wall thickness of 1/16-inch to the eVMV. This will be used to connect the Vacutec.
Run the Vacutec machine leak verification pressure test. Position the control lever located on the Vacutec machine to “meter.” Calibrate the Vacutec machine flow meter using the 0.020 (DTC P0456) standard as follows:
- Insert the transparent air supply hose nozzle tip into the 0.020 inch calibrated leak located on the front of the Vacutec machine.
- Press the remote starter button on the Vacutec machine. Observe the position of the flow meter indicator ball.
- Position the flow meter red pointer flag so that it aligns with the bottom of the indicator ball.
- Release the button and remove the transparent air supply hose nozzle tip from the Vacutec machine.
[PAGEBREAK]Connect the transparent air supply hose nozzle tip into the hose adapter. Press the remote starter button on the Vacutec machine. Observe that the position of the flow meter indicator ball goes from the top of the meter to the very bottom. This validates that you have properly-sealed connections between the Vacutec and eVMV.
Turn the ignition key to the on position. Using IDS, access the PCM and control the canister vent valve (CVV) (EVAPCV PID) and the eVMV.
Close the CVV by commanding the EVAPCV PID to on (100% duty cycle). Open the eVMV valve by commanding the EVMV PID to on (1,000 mA). Press the remote starter button on the Vacutec machine. Notice that the ball in the flow meter is all the way at the top. This indicates the system is being pressurized.
Continue to press the remote starter button until the ball stops descending and stabilizes for 30 seconds (this takes between three to five minutes).
If the ball is at least 1-ball-size below the indicator flag, the EVAP system has passed the leak test. If the ball is at or above the indicator flag, the EVAP system has failed the leak test.
If the test passes, clear the DTC(s), repeat the self-test, and return the vehicle to the customer.
If the test fails, first check for a loose or damaged fuel filler cap, and clean with a shop rag if dirty. Check for the tether binding and re-run the Vacutec leak test if any adjustment/cleaning is made to the fuel cap. If the test now passes, clear the DTCs and return the vehicle.
If the system has still not passed, check the CVV function by capping off the fresh air hose near the CVV and re-run the Vacutec leak test.
If the system still has failed, the Vacutec smoke test is required to isolate the location(s) of the leak.
Run the Vacutec smoke test. Position the control lever located on the Vacutec machine to “smoke.” Remove the fuel filler cap. Remove the Vacutec’s transparent air supply hose from the hose adapter and replace it with the black smoke supply hose.
Turn the ignition switch to the on positon. Use IDS to access the PCM and control the canister vent valve CVV (EVAPCV PID) and the eVMV (EVMV PID). Close the CVV by commanding the EVAP PID to “on” (100% duty cycle).
Open the eVMV valve by commanding the EVMV PID to “on” (1,000 mA).
Press the remore starter button on the Vacutec machine to instroduce smoke into the EVAP system. If smoke does not exit the fuel filler neck after the system is pressurized, command the EVAPCV PID open (off) to allow air to purge the CVV solenoid. Once smoke is seen at the CVV solenoid, command the EVAPCV PID closed (on).
- Secure the fuel filler cap once smoke is observed exiting the fuel tank neck area.
- Continue to introduce smoke into the system for 60 seconds to obtain pressure.
- Press and release the remote starter button in intervals of approximately 15 seconds on and 15 seconds off, while checking for exiting smoke.
- Use the halogen spotlight provided with the Vacutech machine to follow the EVAP system path and look for smoke exiting at leak points.
NOTE: A hydrocarbon detector can be an effective means to locate leaks in locations where smoke exit is not visible, such as the top of the fuel tank (do not use refrigerant leak detector).
Proceed through the following inspection procedure while pulsing the smoke machine at 15-second intervals:
1. Check the EVAP hoses and connections, eVMV valve, CVV solenoid, EVAP carbon canister, fuel tank, fuel tank gasket, fuel filler pipe, around the fuel tank area, and at the fuel filler cap.
2. Wiggle the components and connections to simulate road bumps, while looking for signs of leaking smoke.
3. If the leak is not detected from the top, check the EVAP system for leaks from under the vehicle.
NOTE: If the leak is in the fuel filler neck between the check valve and the fuel filler cap, smoke under pressure may not reach the leak. If leaking smoke is not found, a thorough visual inspection of the fuel filler neck and fuel filler cap should be performed.
Repair the source(s) of the leak(s), then verify leak repair with the Vacutec machine as described earlier. Connect all disconnected components and clear any DTCs.