928drvr86.5

I just changed my filter for the 3rd time in 6 years of ownership. The car is somewhat of a daily driver during the summer months and I average around 10K miles per year. Each time I have changed the filter it has made a noticable improvement in throttle response. During every change I have blown through the old filter after the gas has drained and it seems very restricted. How often do you change your fuel filter?

NickT

The what?? no really, mine gets done every 2 years or so..

dr bob

Fuel filter replacement is probably a function of the amount of gas that flows through, inverse of the flow rate, and the amount of time that the car sits with no flow. Dirty fuel plays a part in this too I guess.

All that said, my Explorer came with an instruction to not replace the fuel filter until 100k miles. Did it twice in my ownership period. Didn't change anything except the smell of the shirt that I was wearing.

A blow-through 'test' of the old filter is only fair if you put the new filter in long enough to soak the filter medium with fuel. A dry filter will pass air a lot easier than one that has pores plugged with liquid. A 'true' test of the filter would be a backpressure test of old vs new, with the pressure gauge connected on the pump side of the filter.

I suspect that many fuel filters are replaced as part of the 'process of elimination' troubleshooting procedure for possible fuel system problems. Most filters are changed after a problem rather than as some sort of PM. Maybe that's the point of the original question.

A well-respected 928 guru said once that he was not aware of any fuel filter replacement that allowed a non-starting car to start. He sells a lot of fuel filters, so his is a statistically sound observation.


And now (drum roll please....) I need to admit that I have three fuel filters on the shelf, purchased by accident, and have never changed one on the 928. 70k miles, always run good gas, car runs great with no fuel-pump howls and no performance issues. And no leaks. It may be that soon, I'll have he back of the car in the air, tank almost empty, and it will be practical to pull the filter as part of some wax-the-gas-tank chore under there. It's just not on the PM schedule right now, though.

perrys4

Can anyone post where it is located and how big a PIA it is to do? I might add it to my list if it isn't a huge job.

Big Dave

It's located under the rear cover...beneath the rear bumper cover. Not hard at all to reach.


Here's a good write-up of the procedure:

http://sis125.berkeley.edu/928/fuelfilter.html

928drvr86.5

What Dave said, and it's like a ten minute job.

the flyin' scotsman

Agreed but only if the PO or mechanic didn't over tighten the lines. I tried to remove mine as part of PM and found my open ended wrenches not up to task (snap on). Went to the local 'wrench' store and got a set of flared type........worked like a hot damn with no damage to nuts or lines.

RyanPerrella

Yeah I just did mine the other day, the only issue i had was with previous owner oversinching down the fitting, I had a problem with the 17mm nut, on the driver side of the filter, it was a pain but i sprayed it with some wd 40 then the next time i got around to it a few days later it was removed, i would strongly suggest a flare wrench though as the one 17mm nut is very shallow and you dont want to strip it.

perrys4

What about air in the fuel line?

the flyin' scotsman

Not an issue Perry. Just change it out and the system purges itself in no time; as in secs.

Mrmerlin

Hi if your going to open the fuel system make sure that you have on hand the correct number and size of new copper crush washers,and a good set of line wrenches, otherwise a 20 minute job will last all afternoon and you wont be able to drive the car because gas will be leaking from the fuel pump/filter connections, also use gloves and tie rags around your wrists so gas wont run down your arm