Installing an Auxiliary Fuel Port for adding heaters, water heaters and other Sprinter Upgrades to your OM612 Sprinter (T1N 2002–2006)
For: Bosch Fuel Metering Unit 0440020088 / Mopar 05136012AA
⚠️ Disclaimer
Proceed only if you are confident in working with fuel systems. Fuel is flammable and hazardous—take proper safety precautions. Perform this work in a well-ventilated area away from open flames or sparks. Disconnect the battery before starting.
What You’ll Need
- Auxiliary fuel port (barbed or threaded, heater-compatible)
- Fuel-safe drill bit or step bit
- Drill
- Gasket or fuel-safe sealant
- Hose clamp(s)
- Fuel-rated hose (for heater booster line)
- Pick tool or pliers
- Clean rags or shop towels
- Safety gloves and goggles
- Marker
- Torque wrench (optional)
Step-by-Step Instructions
1. Locate the Fuel Tank Access
- Drop the fuel tank partially or fully depending on workspace clearance.
- Alternatively, remove the left rear wheel and access the top of the tank from the side.
- Identify the top side of the fuel tank—this is where you’ll install the auxiliary pickup.
2. Choose Your Tap-In Point
- Look for a flat, clean area on top of the fuel tank. Avoid areas directly above internal baffles or near the main pickup.
- Mark your chosen location with a marker.
3. Prepare the Tank Surface
- Clean the area thoroughly to avoid contamination.
- Double-check that no fuel lines or return lines are directly below the area.
4. Drill the Hole
- Carefully drill into the marked spot using a fuel-safe drill bit.
- Use a step bit if your aux port requires a specific hole size.
- CAUTION: Make shallow passes and stop frequently to avoid creating plastic debris inside the tank.
5. Install the Aux Port
- Insert your auxiliary pickup fitting.
- If it’s a barbed fitting, press it in firmly with a gasket and secure with a backing nut if applicable.
- If threaded, use a fuel-rated sealant or O-ring seal.
- Tighten to snug—do not overtighten, especially if threading into plastic.
6. Attach the Fuel Hose
- Connect your fuel-rated hose to the new aux port.
- Route the hose cleanly toward the heater booster (e.g., Webasto or Espar).
- Secure with hose clamps and zip ties away from sharp edges or hot components.
7. Test the Setup
- Reconnect the battery and key the van to “on” (don’t start).
- Check for leaks at the port.
- If using an electric pump for the heater, prime it to draw fuel and test the heater’s startup.
8. Reassemble
- Reinstall the tank if dropped.
- Secure all hoses and verify clearance from exhaust, suspension, or driveline parts.
Tips
- Install a fuel filter inline between the tank and the heater to protect the system.
- Keep hose runs as short and direct as possible to reduce priming issues.
- Label or document your install for future service reference.