OEM Part Number
Fuel Rail Diaphragms: 2PCS 8M6002988
Tracker Diaphragm: 1PCS 804533
Tool kit: 889431

Specification
8M6002988 – Air/Fuel Regulator Diaphragm
Type: Flat top diaphragm
Internal Structure: With steel balls inside
Application Position:
Fuel or air regulator on port side fuel rail (3.0L engines)
Fuel regulator on port side fuel rail (2.5L engines)
Compatible Engines:
Optimax 3.0L Models (200–300 HP)
Optimax 2.5L Models (135–175 HP)
Notes:
Fits both air and fuel regulators on 3.0L engines
Fits fuel regulator only on 2.5L engines

804533 - Tracker Diaphragm
Design Feature: Short knob on top (tracker style)
Engine Compatibility:
Optimax 2.5L Engines: 135–175 HP
Optimax 3.0L Engines: 200–300 HP
Installation Location: Starboard fuel rail
Used as tracker diaphragm on both 2.5L and 3.0L Optimax engines
Identification: Easily identified by the short knob on the top of the diaphragm

This diaphragm kit restores proper fuel and air pressure regulation in Mercury Optimax engines, helping ensure smooth idle, reliable starting, and stable engine performance.