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Home›Repair guides›Yanmar›Checking the spray patterns of the fuel injection valve

Yanmar 4TNE88 — Checking the spray patterns of the fuel injection valve

Testing & diagnosis

For the Yanmar 4TNE88, from the Yanmar service manual.

Applies to: Yanmar 4TNE88, Yanmar TNE series engine

Procedure

  1. Pump the lever of the nozzle tester 4-6 times per second at the specified injection pressure.
  2. Make sure the pattern is neither stream nor sliver.
  3. Place white paper 30 cm below the nozzle; spray should form a perfect circle.
  4. Ensure no oil drips after injection and no ooze below specified pressure.
  5. Retighten and test again if excessive oil leaks from the overflow coupling.

Tools required

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • Spreading angle 5-10 deg (indirect injection) / approx. 150 deg (direct injection)

Full service-parts list: Yanmar 4TNE88 →

Source: Yanmar service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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