Fuel Filter Replacement and Analysis
 

First off i would like to say thanks to nicolaselias who kindly donated the fuel filter for this review and shipped it from Tampa, Florida all the way to Toronto, Canada, Thanks...

Car: 1999 S80 T6 (my car uses the bigger filter, but some s80's have a smaller filter which will not fit the hoses, use your vin to find out which filter you need)

Symptons of a bad fuel filter: I live in a climate where the winter temperatures can dip to as low as -30C during these times when starting the car the rpm's would dip up and down right after the starter would catch on. I had this exact same issue on two cars now and replacing the fuel filter fixed it.

Tools:
ratchet, 12mm socket, small vise grips, latex gloves.

Procedure:
I did this right after driving the car for about an hour so it was warm and fuel pressure was high in the fuel lines, some say you can release the pressure via a valve under the hood ( i did not) others suggest doing this in the morning after the car stood for a while (i did not) and the fuel pressure subsides...

-This fuel filter is located under the rear passenger door about 10" in.
-Use the 12mm socket and ratchet to undo the bolt holding the bracket
-Once its off the filter is loose, if you look at the hose clamp connector it has a nob stixking out, it works much like a button, press it hard and pull off. This is where i used the vise grips because the connectors had lots of deposits on them and would not budge otherwise.
-When you take the first hose off you are going to get a spray of fuel, thats why you need the gloves. only about a cup full of fuel will come out, dont forget the filter is full of fuel as well and it will start to spill
-Take off the second hose at the back of the filter
-When replacing with the new filter observe the flow direction that's printed on the filter itself, put the bracket over it first and then snap on the hoses, they literally click in and that's how you know its connected.
-put the bolt back on and tighten

! start the car, but expect it to die very fast, that's because there is air in the hoses, start it again and tap the gas pedal a few times to force the fuel pump to push the fuel throught the hoses with air in them...check for leaks and you are done...

I collected the fuel from the INLET side of the old filter and after having it settle overnight this is what i got:
Attachment 23111
This looks very similar to the same procedure i did on my old 97 maxima which looked like this:
Attachment 23112
when you shake things up this is what you get:
Attachment 23113

From these results it is obvious that this is the same problem on two different vehicles which is rust from the fuel tank. This rust collects on the inlet of the filter and the fuel pump has to work harder to push fuel through the filter. Thats why the rpms dip at cold start, all these particles accumulate and gum up at cold temperatures (at least in my case i think)

I was planning on taking pics of the procedure but it was so simple i dont think there is a need. Using the jack stand may help, but i managed without it, do this at your own risk.

always glad to help in any way that I can. Just passing on the favours done for me by people on this forum...

Thanks for the great writeup.

I plan on doing mine in the spring and will take shots if nobody has yet by then.

I would highly recommend releasing the pressure in the fuel lines first. there is a blue cap on the right side of the fuel rail under the hood. Remove the cap, and with a rag over the fitting press the center in (it's like a tire valve). This will release the pressure in the lines some, but gravity will still drain the lines when you disconnect them at the filter. I would also recommend wearing safety glasses while doing this entire job. I'm not Mr. Safety, but when working with splashing fuel in a tight area, odds are someone will get it in their face.

Thanks for this, good stuff.

you're welcome, there are not many write ups on this site, not much stickied unfortunately...

+1...

Good write up.

Old thread, but I'm bumping because it deserves it.

Thanks, i hope a mod can sticky this thread

always wanted my writeup on transmission fluid changing/flushing stickied as well