loud tapping in fuel injection tube

[aquapool]

Upon researching I found out the M30 is known for noisy valves and injectors but it seems to be getting louder. I pulled out the stethoscope and to my surprise it wasnt the valves, it's the loudest on the injection tube. Any known causes for this loud ticking that sounds almost like an exhaust leak. Car runs fine besides its refusal to reverse(by the way anyone have a good deal on a tranny).
changed plugs 2 weeks ago
Just ran through some lucas injector cleaner and no change.

http://www.realoem.com/bmw/showparts.do?model=HD23&mospid=47408&btnr=13_0232&hg=13&fg=15

part #1


1990 535ia prod. date 08/89

[Blitzkrieg Bob]

they can get real loud.

Check out five-o-motorsports for deals on repalcements

[aquapool]

Thanks! I'll replace them as soon as I get the tranny fixed.