Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Hard To Fill With Fuel: Notes
The components that are used for tank venting, and will be diagnosed in this procedure are basically the same for every non PHEV vehicle. The only differences are the locations of the components within the system on each vehicle. The graphics below are intended for reference and depicts the general configuration of the system components for the W-Body vehicles with gas engines.
| CALL-OUT | DESCRIPTION |
|---|---|
| 1 | Grade Vent Valve (GVV) |
| 2 | Auxiliary Fuel Delivery Pump/Level Sensor Module |
| 3 | Multifunctional Control Valve (MFCV) |
| 4 | Grade Vent Valve/Fuel Tank Pressure Sensor |
| 5 | Double Port Grade Vent Valve |
| 6 | Canister Tube |
| 7 | Recirculation (Recirc) Tube |
| 8 | Primary Fuel Delivery Pump/Level Sensor Module |
| 9 | Inlet Check Valve (ICV) |
| 10 | Fuel Filler Tube |
| 11 | Evaporative System Integrity Monitor (ESIM) |
| 12 | Fresh Air Filter |
| CALL-OUT | DESCRIPTION |
|---|---|
| 1 | Purge Tube |
| 2 | Fuel Filler Pipe |
| 3 | Recirculation (Recirc) Tube |
| 4 | Canister Tube |
| 5 | Fuel Filler Cup |
| 6 | Fresh Air Filter |
| 7 | Filter Hose (Filter to ESIM) |
| 8 | Evaporative System Integrity Monitor (ESIM) |
| 9 | Charcoal Canister |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.