Adding an OEM Sub-Tank to a KZJ95

Toyota Prado 90 Series
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This guide provides information on adding an OEM sub-tank to a KZJ95 series vehicle, specifically focusing on diesel models.

Problem

Retrofitting a sub-tank requires identifying necessary parts, understanding the fuel system operation, and addressing wiring considerations.

Solution

  1. Parts Sourcing: The most efficient approach is to source all necessary components from a vehicle being parted out. This includes the sub-tank, fuel gauge, dashboard center panel (to accommodate the gauge), fuel filler neck, fuel lines, and selector switch.
  2. Fuel System Overview:
    • The diesel KZJ95 utilizes two chassis-mounted solenoids to control fuel flow from each tank to the injector pump (supply and return).
    • The fuel filler neck is a “Y” design, with separate inlets for the main and sub-tanks.
    • There are no in-tank fuel pumps in standard diesel models.
    • The system is not automated; manually switch between tanks. Running a tank dry will require bleeding the fuel system.
  3. Switch Operation:
    • A selector switch on the dashboard allows manual selection between the main and sub-tanks.
    • Switching between tanks is seamless and can be done while the engine is running.
  4. Wiring:
    • The sub-tank gauge wiring is separate for the main and sub tank gauges.
    • The ground for the low fuel light is connected to the ECU.

Relevant Parts

  • Sub-tank (69L capacity for diesel models, approximately 66L for petrol models)
  • Sub-tank fuel gauge
  • Dashboard center panel for sub-tank gauge
  • Fuel filler neck with “Y” connection
  • Two chassis-mounted solenoids
  • Fuel lines
  • Tank selector switch

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