Wrong part or wrong #fuel Chk valve
 

Trying to check and or replace my fuel check valve and have run into two issues:

1. valve passes the "blow through it test". air can only be blown through on one side. is that enough to leave the valve in place or is there a better test. if valve is good then second issue doesn't matter.

2. part that I ordered according to PET and double checked does not fit into fuel pump. threads are completely different size and pitch. valve actually fits into pump without contacting necessary threads-valve is quite a bit smaller.part was bought from dealer in porsche stapled bag. part number

944.608.951.01

part I received appears to be 10mm fine thread while part I'm replacing is probably a 12mm with thicker thread. could it be the wrong part in the right bag or can my pump be somehow different (appears to be stock but can't find a part number)

Thanks for any wisdom!

It sounds like the valve you have is fine. It's only job is to make sure the fuel can pass through one direction but keep the pressure on after the pump quits running. IF you can't blow through it backward, I would put it back in.

As for the part number look it up in PET online.