⚠️ Duramax Diesel Misfuel Warning
If gasoline has been added to a Silverado HD, Sierra HD, or other GM Duramax diesel:
- Do NOT start the engine
- Do NOT cycle the ignition (fuel pump may prime the common rail)
- Contact a USIFDA certified technician immediately
⚠️ General Motors Position
GM warranty excludes damage from improper fuel. Fuel tank draining, pump access, and tank removal procedures are published in GM Service Information and ACDelco TDS. USIFDA certified technicians follow those OEM steps.
Vehicle Specifications (US)
| Specification | Details |
|---|---|
| Models | Chevrolet Silverado 2500HD / 3500HD; GMC Sierra 2500HD / 3500HD |
| HD Diesel Engine | 6.6L Duramax turbo diesel (LML 2011–2016; L5P 2017+—confirm by model year) |
| High-Pressure Fuel Pump | LML uses CP4.2—documented sensitivity to gasoline contamination; consult GM Service Information |
| DEF | Required on modern Duramax—never add DEF to the diesel fuel tank |
| Fuel Tank Capacity (typical) | ~36 gal (2500HD single tank—varies with bed/cab; consult OEM) |
| Gasoline HD Options | 6.6L gas V8 available on some HD models—always verify fuel door label |
Other US GM Duramax Models
- Chevrolet Colorado / GMC Canyon: 2.8L Duramax diesel (2016–2022)
- Chevrolet Silverado 1500: 3.0L Duramax inline-six (select years)
- Full-size SUVs: 3.0L Duramax in Tahoe/Suburban/Yukon/Escalade (select years)
All use common rail systems sensitive to gasoline in diesel. Access and tank capacity differ—consult ACDelco TDS for the specific VIN.
GM Service Procedure Summary
Fuel Tank Service (typical sequence)
- Relieve fuel system pressure
- Disconnect negative battery cable
- Drain fuel tank using approved recovery equipment
- Disconnect filler, vent, and fuel lines as required
- Lower tank per Silverado HD / Sierra HD service manual
USIFDA Recommended Methods
✓ Method A: Module Access (when documented)
Where GM service information allows in-tank pump access without full drop and the engine was not run on wrong fuel.
✓ Method B: Full Tank Drop
Required after engine run, for full flush, or when OEM mandates tank removal (common on HD trucks).
✗ Filler Neck Extraction
Not Approved as a standalone certified process—follow GM prescribed tank/module procedures.
⚠️ CP4.2 and System Contamination
On LML 6.6L Duramax (2011–2016), industry service experience reports that gasoline contamination can contribute to high-pressure pump distress. If the engine was run, assume possible metal contamination of rails and injectors until inspected per GM Service Information. Do not speculate on coverage—document OEM procedures.
Estimated Labor Time
| Scenario | Typical Hours |
|---|---|
| Drain without engine run | 2 - 4 hours |
| HD tank drop and flush | 4 - 8 hours |
| Fuel system component replacement | 8+ hours |
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