How to Replace Fuel Pump Assembly on 2006 Montero 3.8 Gasoline/Petrol

pwjazz

Member
My 2006 Montero's been having issues with hard starting and what seems like loss of power on hills. The fuel pump also sounds pretty loud when the ignition is on and before I crank. With more than 150K on the odometer, as far as I know, the fuel pump has never been replaced. All this pointed me to thinking that either the fuel filter needs replacing, the pump is going bad or the regulator is going bad. Testing the fuel pump on these seems like a pain in the butt and looks like it requires special equipment. Replacing just the fuel filter is possible, but also seems like a bit of a pain. I managed to find an open box OEM fuel pump assembly on eBay for $150, so I decided to just replace the whole assembly. I haven't driven enough yet to know if it solved the problem, but here's what I did to change it out. It took me about 2 hours, if I wasn't such a newbie it would have probably been a 1 hour job.
  1. Watch this video
  2. Have a fire extinguisher near by (gasoline is flammable yo)
  3. Before installing, test the new pump's resistance with a multimeter. The resistance across the two leads on the pump was between 1-2 ohm, which I think means it's not burned out anyway.
  4. To remove any pressure from the fuel lines, start the engine and then pull the fuel pump fuse while the engine is running (see item D in pictures). This is fuse no. 6.
  5. Follow the video's instructions to remove the two plates covering the fuel pump assembly. The inner plate required some prying to remove, as it looks like it had some sort of adhesive seal (or maybe just really broken down foam)
  6. There was quite a bit of dust/dirt on top of the fuel pump and hoses. I tried vacuuming it, but that didn't do much, so I wiped what I could with a dry paper towel.
  7. Remove the power supply (item B in picture). There's a little tab you need to push in to unclip it.
  8. Remove the hoses. Unlike in the video, my Montero also has differential fuel pressure sensor (item C in pictures). The easiest way to deal with this is unclip the whole sensor from the fuel pump assembly by spreading the two white clips that hold it. After pulling it out, you can remove it from the wiring harness by unclipping the retaining clip that holds it in place (see pictures).
  9. Another note about the differential pressure sensor - my new assembly came with part number MR507384. When I look that up online, it doesn't show up as a Montero part, but rather an Endeavor part. However, the pump that was already installed had the same part number, and it seems to work, so I guess it's okay.
  10. Unscrew the ring that holds the fuel pump to the tank. This ring may look symmetrical, but it's not! The inner circumference has three notches that line up with 3 tabs on the fuel pump assembly, and the outer circumference has a half moon notch that's supposed to point towards the front of the car.
  11. Clean the metal ring (it was pretty nasty on the outside)
  12. Have a plastic tray handy, then pull out the pump and put it in the tray. The fuel sock will probably get caught, so twist the pump assembly around until you find a good angle for getting the sock out.
  13. I tested the resistance of the old pump, which was also between 1-2 Ohm, so the pump may be okay. I'm hanging on to it for now, just in acse.
  14. Remove the rubber gasket that goes between pump assembly and outside of tank. My new assembly came with a new gasket, so I'm replacing the old one.
  15. Place the new fuel pump and gasket. The sock is flexible and curls up on itself when pushing the new assembly in, so after wiggling it into the tank, I pulled it back out until the sock was flatter again, then lowered the pump all the way down.
  16. Screw in the metal ring (remember, the inner notches have to line up with the tabs on the pump assembly, half moon notch needs to face towards front of car). Once it's on right, there'll just be a tiny gap between ring and fuel tank that's even all around.
  17. Connect the hoses, remember to slide on the hose clamps. My pump assembly came with a new differential pressure sensor, so I took it out of the assembly and connected that to the wiring harness and secured it with the original clip. Then I clipped the whole sensor into the fuel pump.
  18. Vacuum to get rid of the dust that fell on the new pump. In particular, I wanted to make sure the seat for the power supply was clean.
  19. Connect the power supply. You'll hear it click in place once it's seated all the way.
  20. Replace the fuel pump fuse and make sure the Montero starts and runs (it did, yeah!).
  21. With the engine running, take a look in the fuel pump well and makes sure nothing is leaking.
  22. Replace the inner and outer cover.
fuse.jpeg

cover.jpeg

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pwjazz

Member
Well, it still cranks a little longer than I'd like before turning over, but the RPMs don't die right after turning over like they used to, and seat of the pants it does feel peppier under full throttle. It might also be running a smidge cooler than it used to, but I'm not sure. Also, nothing's caught fire, so I'm going call this a success.
 

Michael Brown

You followed me, so now we're both lost
Nice writeup. I had to do this a couple years ago when my pump died in a parking lot.
I was also lucky enough to have just topped off the tank when it went bad.

A couple points I would add:
- Use lots of penetrating fluid on the small nuts and studs holding the ring on the pump. Run a thread die over them or brush to get off rust. They will snap if the nut binds on the rusted threads.
- If your tank is full, you will spill gas. There is a drain plug on the bottom of the tank. Lower the plastic cover to see it.
- Some of the hoses and connectors can be reached from underneath the passenger side as well.
 

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