I have had a problem with fuel leaking at the flare fittings where the injector lines bolt to the top of the injectors. Fuel doesn't spray out thankfully it only just drips out, but it has happened twice and no amount of tightening seemed to help, both times had to replace injector lines to fix problem. Any ideas why this is happening. This on my '87 6.9l. Thanks Grant

 

are all the clamps in place on the lines? each sice has atleast 2 clamps that hold the lines together. without them the lines will fatique from vibrations and crack.

clamps can be seen in this pic. painted red to match lines.

 

my engine doesn't have any clamps on the injector lines, but guess i will be adding some soon so this doesn't happen again. thanks dieselcrawler for the help.