Lancelot: I don't believe it's leaking out around the tester. I've had that happen in the past, where I didn't have the gauge solidly screwed onto the test port. This time, I had the plenum off, so I had a clear view of the connection. My gauge doesn't have a pressure relief; it's just a Harbor Freight cheapo. (Hey, maybe that's the problem!)

Captain: I'll try to rig up a shut off valve like you suggested, and see what that tells me. Also, I can't remember for certain, but I'm pretty sure when I bench tested the pump, I had it separated from the sending unit assembly. I wonder if my cheapo sending unit might have developed a small crack in the metal lines? That might explain why the pump holds pressure, and I've got a brand new spider/regulator, and still leak down issues when it's all together. I'll dead head the pump to the gauge and test it, when I test with my shut off valve rig.

 

Might be a leak in the flexible line that runs from the pump to the module. Kinda looks like an accordian and it's about 7" long. Gotta make sure there are no splits in the line, and the clamps are tight. If you dead head at the fuel filter outlet and it leaks down, that's most likely the problem. If it holds pressure, the problem is in the plenum. I forgot you have a 95, leakdown is allowed to drop no lower than 50psi, not 55psi as I mentioned above.

 

Check your lines for severe rust where they sit on top of the frame. I have my tank dropped right now. I'm at pause mode because I had to order new rear fuel lines (fuel, return, vapor). I don't know about a '95, but on my '98 ZR2 where the lines make the bend on top of the frame heading toward the pump was a rusted mess. Right where the bracket is on top of the frame inside the driver's side wheel well. I didn't like the look of them when I started taking the tank out and my concern was verified when I was disconnecting the lines from the pump. As I disconnected one of the lines it just snapped off at the bracket. The whole tube was rusted all way around and where it snapped at there was NO good metal. It was tissue paper thin. I'll try to get a pic posted. I suspect that my leakdown may have been coming from that/those lines. I only did a half-*** diagnosing where the leak was coming from beforehand because I knew I was dropping the tank anyway to replace my leafspring shackles and decided to put a new pump in while it was down.

 

Captain, I don't have the accordion connector, mine is all hard line. I was kinda rough with it getting it in and out of the tank, maybe I cracked one of those bends? I reused the little piece of rubber hose that connects the actual pump to the sending unit, maybe the problem is in there.

And rockp2, we don't have quite the rust issues down in Texas, as you guys in Pennsylvania, but I'll definitely give the lines a look over before I give up on finding the cause!