On Robin's scale of difficulty (1 to 10) I would rate this task a 5. It took me about 3 1/2 hours to do this, but I was learning as I was doing and I ran into a couple of stubborn nuts. I think with this DIY you should be able to complete the job in 1-2 hours without too much difficulty. I would not attempt to change the fuel filter after having recently driven the car. Check valves in the fuel lines are meant to maintain pressure to help prevent vapor lock. I had not driven the car for a week and had no issues with remaining pressure in the fuel lines. I suspect 24 hours would be more than enough of a delay to let any remaining fuel pressure bleed off.
Note: In this DIY the air filter housing was removed to gain better access to the fuel filter fittings, it is possible to replace the fuel filter without removing the air filter housing if you have stubby wrenches and are confident with your wrist torque. The procedure to remove the air filter housing on a 95 993 is simpler than the below procedure list (for 96+), please check out this DIY for 95 993 air filter housing removal.
The only part you'll need is a new fuel filter (part # 928 110 253 00).
Wrenches: 17mm Flare nut, 19mm Flare nut, 19mm Open, 7/8" Open
Screwdrivers: 3/16" Slotted, #2 Phillips, #2 Phillips with minimum 8" long blade
Ratchet: 3/8" with 10mm socket.
The fuel filter is located on the right side of the engine bay just in front of the power steering fluid reservoir. To provide room to work it is highly recommended you remove the entire air cleaner housing. I've been told others have changed the fuel filter without doing this. However, the factory manual calls for it and if you don't I think you'll need stub wrenches.
Remove the "snorkel tube" from the front of the air cleaner housing. This is a friction fit and if you squeeze the sides you should be able to easily pop it out. Undo the two clips holding the air cleaner housing cover on and remove the cover and air filter inside the housing.
Using the 3/8" ratchet and 10mm socket remove the support bolt for the left half of the air cleaner housing. Remove the temperature sensor connector by pushing and holding down the metal clip and gently pulling the connector off the back of the air cleaner housing. The temperature sensor will remain attached to the air cleaner housing.
Next the mass air flow sensor has to be rotated forward towards the front of the car to unlock the bayonet lock that holds the air cleaner housing and mass air flow sensor together. To allow the mass air flow sensor to rotate the hose clamp holding it in position must be loosened and the electrical connector to the mass air flow sensor removed. First use the 8" #2 Phillips screwdriver to loosen the hose clamp. The clamp can only be accessed by inserting the screwdriver just to the right of the Idle Speed Control unit which is located on top of the intake manifold near the top center of the engine bay. I was able to use my right hand to reach around over the top of the air cleaner housing and use my right hand fingers to guide the screwdriver in my left hand to the hose clamp behind the Idle Speed Control. Doing this also ensures the hose clamp doesn't rotate making it very difficult to put everything back together.
Disconnect the electrical connector to the mass air flow sensor by turning the plastic locking ring and then gently pulling the connector off of the mass air flow sensor. The connector is shape coded so you don't have to worry about remembering proper pin alignment.
The mass air flow sensor can now be rotated forward towards the front of the car to unlock the bayonet lock between it and the air cleaner housing. Rotate the mass air flow sensor forward about 1 inch to completely disengage the lock.
The air cleaner housing sits on two rubber mounts. The housing can now be lifted up about 3/4" to clear these mounts and then it can be separated from the mass air flow sensor. There is a sealing gasket between the air flow sensor and the air cleaner housing. The gasket is held in place on the air cleaner housing by three plastic fingers and should not come out, but use care to ensure the gasket isn't lost or damaged. The last step to removing the air cleaner housing is to disconnect the rubber hose connected at the lower left corner of the housing. With the air cleaner housing in place the house clamp is pretty well hidden behind the forward right cylinder intake runner. By waiting until the air cleaner housing is off of the rubber mounts and disconnected from the mass air flow sensor you can maneuver the air cleaner housing and rubber hose to a position that will allow you to loosen the hose clamp and separate the hose from the air cleaner housing. Removing the air cleaner housing from the engine bay is somewhat of a jigsaw puzzle because of the tight fit. Be patient.
Now that the air cleaner housing is out of the way there is plenty of room in which to work. You'll need a good supply of rags and a small can to catch the gas that will inevitably come out of the filter. I chose to undo the connection near the rear of the car first. I used an 19mm open wrench on the filter side nut to hold the filter steady and a 19mm flare wrench on the fuel line nut to break the connection. This connection was not particularly tight and the leverage angle of the wrenches is not too awkward. Once the fuel line was off enough gas came out to fill my Minute Maid can up about 1/3 of the way. The connection towards the front of the car was a different story and I think Hercules himself put that one on.
Theoretically, you should be able to use a 17mm and 19mm flare wrench on the connection towards the front of the car. However, it is up underneath the front of the engine bay and the leverage angles are awkward. After 5 minutes of grunting and groaning with no obvious movement of the two nuts I chose a different approach.
First, loosen the fuel filter hose clamp. Then I put the 17mm flare wrench on and braced it against the side of the engine bay to hold the fuel line steady. Finally, I used the 7/8" open wrench on the nut shaped portion of the fuel filter (side facing rear of car) where I had already undone the first connection. This allowed a much better leverage angle on the 7/8" wrench / fuel filter. Using this method I was able to get the fuel filter off. However, it left the 19mm nut that was originally part of the fuel filter connected to the 17mm fuel line nut. Also, once the fuel filter started to come loose another 1/3 of a cup of gas came pouring out from the already open end of the filter (like opening the vent plug of a 5 gallon gas can). Unfortunately, I had moved my Minute Maid can so a word to the wise is to leave the can in place until the filter is completely off.
The fuel line is supported by a bracket a few inches farther forward in the engine bay (see previous pictures). A few inches farther upstream from the bracket, the metal fuel line changes to a rubber line. By loosening the fuel line support bracket I was able to move the fuel line into a position that I could use the 17mm and 19mm flare wrenches with a good leverage angle and was finally able to separate the two nuts.
The fuel line support bracket is freed up by loosening a 10mm bolt in the right rear wheel well that screws into the six-sided plastic nut on the support bracket (see previous pictures). To gain access to the wheel well bolt I had to jack the right rear side of the car enough to get the chassis up off the suspension. My car is lowered about 2" so on a normal car you may not have to do this. One final note, there is a black plastic offset washer between the fuel support bracket and the side of the engine bay. Don't forget to put this back in place when putting everything back together (yes, the voice of experience).
All that remains is to put everything back together again pretty much in the reverse order you took it all apart. My order was:
1. Reattach the fuel line support bracket (remembering the offset plastic washer!).
2. Insert new fuel filter and attach to the forward 17mm fuel line nut. Be careful to get the filter oriented the proper direction. There should be an arrow on the fuel filter itself (should point to the rear of the car) and the nut arrangement between the fuel lines and filter are one directional, but just be sure.
3. Attach the other fuel line (19mm nut).
4. Secure the fuel filter hose clamp. I used a black Sharpee to mark the mileage and date on the filter for future reference.
5. Attach the rubber hose to the lower left corner of the air cleaner housing.
6. Set the air cleaner housing onto the two lower rubber support mounts and work the mass air flow sensor into the back of the air cleaner housing being cognizant of the sealing gasket.
7. Rotate the mass air flow sensor to the rear of the car to re-engage the bayonet lock between the air flow sensor and the air cleaner housing.
8. Secure the 10mm support bolt on the upper left half of the air cleaner housing.
9. Tighten the mass air flow sensor hose clamp with the 8" #2 Phillips screwdriver. Again, I used my right hand to hold the clamp in place while using a screwdriver in my left hand to tighten the hose clamp.
10. Reattach the mass air flow sensor connector and the air cleaner housing temperature sensor connector.
11. Replace the air filter, the air cleaner housing cover and the "snorkel tube."
Finally, I had my wife, who was wondering what the heck I'd been doing for the last 3 hours, start the car while I stood at the ready with a fire extinguisher and checked for leaks. It will probably take a couple tries before the car will start up.
There is nothing particularly difficult about this DIY. The hardest part is removing the air cleaner housing. However, once this is done, assuming Hercules didn't tighten the fuel line nuts, the replacement of the filter is pretty straight forward. Hopefully, this will be of use to those who choose to do this themselves.