1978 BMW 630CSi Automatic TransFACTORY OEM SERVICE PROCEDURE

Fuel Emissions System: Description

System consists of purge lines from fuel tank to crankcase ventilation system. Located between fuel tank and crankcase ventilation system is a vapor storage tank and an activated carbon canister. Fuel evaporation emissions are prevented from entering atmosphere by means of a sealed filler cap on fuel tank. Fuel tank has no direct vent to atmosphere. An excess fuel return valve is also used, located in fuel supply line near carburetor. A fuel return line connects this valve to fuel tank.

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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