Wrong Fuel Filter in My 911

kevjandon · 04-13-2005, 07:05 AM

I finally got the fuel filter to break loose last night. Penitrant and Muscle did the trick.

Anyway, when I got it off and laid it side by side to the new one, I noticed they are not the same filter. I'm pretty sure the new one is the right one as it says 911 3.01 on the box (Mahle filter BTW). I double checked my order and the part numbers all match. On the can it say ML22 if I remeber. The one I took off says ML21. I may have the 22 and 21 backwards, but I think I'm right. I also noticed that the 78 to 80 SC's had a different filter than the 81 to 83's. I'm guesing the filter I took out was for the 78 to 80.

Anyway, the old filter looks about 20% bigger than the new one. Was the old filter causing any problems due to it's size? Maybe the fuel pump couldn't keep up. It will be interesting to see if I can notice a difference. Maybe better throttle response?

Let me know what you all think.

kevjandon · 04-13-2005, 08:56 AM

anyone

mperkins · 04-13-2005, 09:03 AM

I had a similar problem months ago. I ordered a Mahle fuel filter (the larger one) and later realized only the Bosch filter (narrower size) will fit my '80 SC. It was obvious right away - the filter fittings and my fuel hose fittings did not mate.

Perhaps you require the Bosch. Hope this helps.

sammyg2 · 04-13-2005, 12:24 PM

Check the threads for the fittings, some have 13mm on both ends, others have 12mm on one end. If it doesn't match yours you will have a problem.
I dunno why, but this comes up about every 6 months. I had the same problem when I ordered a new fitler, the wrong one showed up. Either the books are wrong or Porsche put whatever they had laying around in there. The filter I needed ended with 016 but that was not the one that everyone wanted to sell me. At the time I could not find the right filter so I adapted the fittings so I could use the common filter. Soon after that I found the filter I needed but it was too late.

Rick Lee · Rick Lee's Garage

I wondered this myself, when I got my filters mixed up between the 993 and SC. The Mahle # on (what I am sure was) the 993 filter matched the number on the old filter on my SC. The new-in-box Mahle SC filter # did not match either. So I used the 993 filter on the SC and it was fine. Sounds crude, but I assume, if the fittings mate, then it's ok.

Porsche_monkey · 04-13-2005, 01:26 PM

I think it is highly unlikely the volume of the pump made any difference. Only at full throttle would any fuel starvation occur. Your consumption rate is likely only a fraction of what the filter can handle, and the fuel pumps 'capacity' is determined by your engine once the system is pressurized.

rhaas · 04-13-2005, 03:01 PM

I took the fittings off a vw gti that has a large fuel filter that I could redily get at my flaps. I just get the filter for the vw now. Been doing this for years with no problems.