My 1991 e30 318is was having a problem when starting after it had been parked with the engine hot for more than 15-20 mins.
Symptoms were as if it had no fuel in the line. Cranked over 6-8 times and then stumble and start and run fine.
I did research on the internet and found that similar problems had been posted on other BMW websites. see: http://www.bmwe34.net/E34main/Trouble/535ihot_start.asp
I never checked with BMW in Canada for availability.
Note: The repair kit is inexpensive but costs more than its worth in shipping.
Bulky packaging. Kit consists of the replacement fuel line with the check valve already attached (you will cut this to length for your application) and some new clamps (crimped type clamps you may wish to replace with screw type clamps) and some insulation tubing and plastic nut covers (this can be discarded as you may not use this for your repair)
I finally had enough and I purchased BMW check valve p/n 16149068988 from Steve Haygood in the states. You can see his site at http://www.stevehaygood.com:80/
Car starts without hesitation now!!!!