DMAX, MUX, BT50 4JJ3 Pre-Filter - 2020 On - Fuel Manager FM645DPK

• Fuel Manager pre-filter assembly with clear drainage bowl
• Vehicle-specific mounting bracket
• Fuel line kit (hoses and fittings)
• Water drain assembly
• Mounting hardware (bolts, washers, nuts)
• Installation guide

Note: Replacement pre-filter element is Direction Plus 31863 (30 micron), sold separately.

The unit mounts between the tank and the factory filter and removes the majority of the water and particles. The factory filter then handles the final fine filtration. A robust two-stage defence for a modern common rail diesel.

• Up to 95% water separation, stripping water before it reaches the factory filter
• Separates emulsified water in ULSD fuels
• Reduces wear on injectors, pump and rail
• Clear drain bowl for quick visual checks and easy draining
• No bypass design: contaminated fuel is not passed on to the injectors
• High-flow design, built to maintain fuel pressure
• Helps avoid injector and fuel system repairs that can exceed $10,000

• Isuzu D-Max 4JJ3-TCX (3.0L 4cyl): 2020 on
• Isuzu MU-X 4JJ3-TCX (3.0L 4cyl): 2020 on
• Mazda BT-50 4JJ3-TCX (3.0L 4cyl): 2020 on

BT-50 owners: This kit is for the Isuzu-based BT-50 with the 4JJ3 engine only. The earlier Ford-based BT-50 (P4AT 2.2L and P5AT 3.2L) uses a different Direction Plus kit (FM621DPK). Check your engine code if unsure.

Fitment per Direction Plus as of October 2026. Check the fitment guide or send us your VIN if unsure.

• Mounts in the engine bay on the supplied vehicle-specific bracket.
• Installed between the fuel tank and the factory filter.
• All fuel lines and fittings included. No cutting or fabrication required.
• Allow 2 to 3 hours for a competent DIYer. If you have not worked on fuel systems before, have a qualified mechanic fit it.

• Check the clear bowl weekly or before long trips.
• Drain water as soon as you see it: open the drain, let it run until clean diesel comes out, close it.
• Replace the element generally every 20,000 to 30,000 km, sooner on farm, drum or remote fuel.
• Inspect the fuel lines at each service.

• Free express shipping Australia-wide.
• Tracking sent as soon as it is on its way.
• Afterpay, Humm, Klarna and Zip available.
• Returns and warranty are handled under our refund policy.

Q: Does one kit really fit the D-Max, MU-X and BT-50?
A: Yes. Direction Plus lists FM645DPK for the Isuzu D-Max, Isuzu MU-X and Mazda BT-50 with the 4JJ3-TCX engine, 2020 on. They share the same engine and fuel system.

Q: Which BT-50 do I have?
A: If it has the Isuzu 4JJ3-TCX 3.0L, this is your kit. The earlier Ford-based BT-50 (P4AT or P5AT) uses Direction Plus FM621DPK instead. Check your engine code or send us your VIN.

Q: What is emulsified water?
A: Water mixed so finely into the fuel that it looks cloudy instead of settling out. ULSD is more prone to it. The Fuel Manager is designed to separate it.

Q: Why do I need a pre-filter if I already have a factory filter?
A: The factory filter is designed for fine filtration and has limited capacity for bulk contamination. The pre-filter does the heavy lifting, so the factory filter lasts longer.

Q: What does no bypass mean?
A: Many filters open a bypass valve when they clog and let unfiltered fuel through. The Fuel Manager has none. All fuel passes through the element, so you must keep it serviced.

Q: Can I add a catch can later?
A: Yes. Plenty of 4JJ3 owners run a Fuel Manager pre-filter and a ProVent catch can. One protects the fuel system, the other the intake.