Fuel Delivery Issues in Toyota Prado 120 Diesel: Diagnosing and Cleaning the Fuel Pump Assembly

Toyota Prado 120 Series
1

Introduction

This guide addresses a potential fuel delivery issue in the Toyota Prado 120 diesel, specifically related to fuel starvation when the fuel tank is approximately half full. This issue can manifest as the engine sputtering and behaving as if it has run out of fuel, despite the fuel gauge indicating a significant amount of fuel remaining.

Problem

The primary symptom is the engine behaving as if it has run out of fuel when the fuel gauge indicates approximately half a tank remaining. Adding a small amount of fuel (e.g., 10 liters) resolves the issue temporarily, allowing the vehicle to run normally until the fuel level drops to the same point again.

The underlying cause is often traced to a blocked or restricted fuel pump assembly within the fuel tank. Specifically, a swing valve at the bottom of the pump housing, responsible for drawing fuel when the tank level is below the pump housing, can become clogged.

Solution

The recommended solution involves removing and cleaning the fuel pump assembly.

  1. Access the Fuel Pump: Drop the fuel tank.

  2. Inspect the Fuel Pump Assembly: Examine the fuel pump assembly for any signs of sludge, debris, or blockages. Pay close attention to the swing valve at the bottom of the housing.

  3. Clean the Components:

    • Clean the swing valve to ensure it moves freely and is not obstructed.
    • Clean the mesh sieves (strainers) within the fuel pump assembly. These sieves are prone to becoming clogged with sludge.

  4. Reassemble and Test: Reinstall the cleaned fuel pump assembly into the fuel tank, remount the fuel tank.

  5. Monitor Fuel Consumption: Closely monitor fuel consumption and performance, especially when the fuel level approaches half a tank, to ensure the issue has been resolved.

SOLUTION: Removal and cleaning of fuel pump assembly and in particular the swing valve and mesh sieves.

Relevant Parts

  • Fuel pump assembly (located inside the fuel tank).
  • Two mesh sieves (strainers) within the fuel pump assembly.
  • Swing valve (located at the bottom of the fuel pump housing).

Additional Notes

  • It’s advisable to carry a spare amount of fuel until you are confident that the problem has been fully resolved.
  • Inspect the area between the fuel tank and its guard for accumulated rocks and debris.

This technical summary was auto-generated based on recovered archives. Do not rely on its factual accuracy. Refer to the original thread. Source: View Original Conversation

Continue the discussion below.