The QX4 has had some starting issues and I thought the fuel pressure might be the issues. Turns out it was a good hunch as the fuel pressure according the FSM should be between 34-43psi
Here was my process of replacement.
First you need to relieve the fuel pressure. This is done by removing the 15 amp fuse located on the interior fuse panel. (Bottom left side of steering wheel pull coin tray out)
Start the car and wait for it to die...Start the car again and make sure it won't start.
You have now depressurized your fuel system...
First the access hole is underneath the drivers side rear seat by where the jack and tie rod are stored. Move the carpet out of the way as some gas is bound to spill.
Remove the cover by removing the 4 bolts with a 10mm socket or Philips screw driver. Once removed you can push the rubber grommet in the center of the cover out and be able to move it out of the way some so you can better get to the eclectic connections.
Go ahead and disconnect the two electric connections. I used a flat head screw driver to gently push in the connector clip while gently tugging upwards on the connection until it comes lose.
Go ahead and loosen the hose clamps and remove both hoses from the pump assembly. Make a note of which hose goes where (or refer to this pic when you forget)
There will be some gas that spills here...
I went ahead a cleaned the area up as best as I could as it was pretty dirty (see last pic) this is done so when I lift the pump assembly out of the tank all that dirt does not fall into the tank
Now go ahead and remove the 6 screws holding down the assembly ring with a Phipps screwdriver. Be careful they are very short and easy to lose. Remove the black retainer and set aside.
Go ahead and lift the assembly out of the tank carefully. It is not going to come all the way out yet as we have to disconnect the hoses first.
You disconnect the hoses by pushing in the top tabs with your fingers don't be rough with it. Pilers like to break these so tread carefully if you choose to use them. I was able to push in with my fingers in one hand while pulling downward while slightly twisting and they came free. Lastly discount the pump electrical connection. Pay attention to what goes where I made some sharpie marks to help me when I put it back together.
You now can remove the float assembly completely. Due so carefully and do not force anything. Set it aside.
Here comes the tricky part your old fuel pump is in the bottom of the tank and you have to reach in and get it out of there.
Now I learned the hard way...When you reach your hand down in there the edges of the tank are VERY VERY SHARP! It did this to my arm in no time...
So let me save you some pain and blood and put some masking type around the edges to protect your arm.
Now when you reach down into the tank the pump in held done their by this clip (this pic was from after it was out already so you can see it better to get an idea of what your feeling for. A tip that was offered to me was to come at it with your left hand from the passengers side. That angle you can see what your doing better. You have to push on the middle clip in order to release it from the bottom of the tank. Now for me this where I got hurt when the pump did release I was pulling with some force and my arm jerk back scrapping against the edge of the tank cutting me up pretty good so make sure you have the masking tape on it in case that happens
Here is the old pump once removed from the tank
You have to remove the actual pump from the housing it sit in. This is pretty simple there are two tabs on each side just push those in and it will come right in 2 halves reveling finally the fuel pump that needs replacing. Pay close attention to how the pump is seated in the housing and where the black rubber spacer goes...
You are also going to have to undo the clip the holds the hoses and wires in a bundle in order to swap out the old pump for the new one
Now ready your new pump to assemble into the housing. Just put it back in the reverse of how you took the old one out.
Here is an image of the new pump all set in the bottom half of the housing. This is taken from the top looking down. Make sure you have the black rubber spacer in their and it looks like this...
Now just snap the top half of the housing back on and you have a fully assembled new fuel pump ready for business.
This next part is the hardest part of the whole process. You have to snap the pump back into the slots in came out of at the bottom of the tank...There was not a good way to take a pic of this process. My tips are as follows...
-Come from the passenger side with your left hand as you can see better.
-Set the pump in the tank and push the hoses and connector under the lip of the tank. This makes it easy to move the pump around without the hoses getting caught on the lip. Study the clip on the pump shown earlier and the slot in the pump box in the tank that what needs to line up. Get in lined up and then push downwards. You may hear a slight click once it snaps in place. You will know for sure if you got it, if when you pull back up on the pump it once again feels locked in place like the old pump did when you removed it. Here is the new pump locked into place..
Now pull back out the hoses and connector through the opening. Also now is the time to replace the o ring in order to ensure a good seal. They are inexpensive and is ALWAYS a good idea to just put a new one in to ensure a good seal.
Carefully place the float assembly partially back in the tank.
Reconnect the hoses and electrical connection to the correct spots you marked earlier. Reconnecting the fuel lines is easier than un clipping them just push them on to the rod until clip in to place. Check the connection by tugging downward on them once clipped in to make sure they do not come off.
Place the float assembly fully back in the tank and make sure it is returned to the same exact location it was when you removed it other wise your hoses may not connect and your fuel gage will not read right. Once you are certain it is in the correct position grab the black retainer and match it up to the float assembly and now put the 6 small screws back in being careful not to over tighten. (This picture was taken from the drivers side for reference when lining up your float assembly.)
Now reconnect both hoses and both electric connections to the top of the float assembly in same places you made notes of where they originally were. Put the clamps back on.
Now before we put the final cover back on it. Its a good idea to test it first so you can see if you have leaks or another problem. To start the vehicle again first reinstall the 15amp fuel pump fuse you removed in the first step. Now you need to re-pressurize your fuel system before starting. This is done by putting your key in the ignition and turning it to the just before where the engine would crank over. Due this 5-6 times. This will re pressurize your fuel system. Now you can actually turn over the engine and the car should start. Try a couple times if it doesn't right away come to life before going back to troubleshoot.
Now check to make sure you have no leaks in your lines.
I went ahead and put my pressure gage back on it to see the difference and it now shows a much improved now in spec 35-26 PSI!
Now you may replace the cover back over the access hole. make sure to put the rubber grommet back as well. Put the 4 screws back in and go wash up and have a beer!
