Trying to find air leak in fuel line

[Woodturner Nate]

I have a leak somewhere in the lines from the tank to the fuel bowl. No diesel is ending up in the valley of the engine, but the fuel bowl is emptying. The lift pump has already been replaced, but the problem persists.

I'm planning on isolating each section of the fuel line and trying a vacuum pump on it to see if I can find the leak by seeing in what section the gauge reads a loss of vacuum. Will I do damage to the injectors/fuel rail if I hook it up straight to the lines while still connected to the fuel bowl? The lines are braided and everything, but my vacuum pump is a decent sized one, like 1/3 or 1/2 horse. My thinking is that it should be fine, but I'm not positive. I was going to start from the rear tank and move forward....

HELP!

[Woodturner Nate]

So I found the leak. Actually, it was two leaks. I didn't really think about what I was posting before. What I ended up doing was disconnecting the lines at the rear tank. I had to replace the rear tank anyway, when I pulled it to check the strainer, I found a bad leak that was being held together by the mounting straps. I then hooked up the OUTPUT of a vacuum pump, dialed in to a pressure of about 15 psi and plugged the end of the other return line. Then came the fun part of wriggling around on my back trying to find a leak. Ended up that in two places where the line goes from flexible to rigid there are crimp-style hose clamps, similar to PEX tubing used in home construction. The years of jiggles and bumps in the road made the clamps loosen over time. It wasn't leaking much, enough to drain the fuel bowl in a matter of 10-15 minutes of hard driving. I twisted off the molded-in crimp clamps and put on some real hose clamps and the leak is gone. Happy powerstroke now.