95 blazer 4.3 cpi question regarding fuel pressure leakdown

Hi, I really wanted to say thanks for the wealth of information here. I was having alot of the same problems as everyone else, so decided to rip apart the truck and take a look. I found that my regulator was bad, and I replaced that and the nut kit as well. My question is about the fuel pressure. I still have everything disassembeld and jumped the pump to check for leaks. No leaks, and it hold steady at 64 psi. However, when I disconnect jump wire from the battery, it immediately leaksdown. I was wondering if this is normal or if it's still suppose to hold pressure like KOEO or if this means the cpi itself needs to be replaced. I'd rather do it while evrythings ripped apart, than put it all back together to rip it apart again. Any help would be appreciated!
Thanks

There is only one way to tell what is leaking. Pressureize the system, isolate the fuel pump from the system, (accomplished with a valve in the pressure line between the pump and the pressure port). Then deactivate the pump electrically. If the fuel pressure holds, the pump is leaking. If pressure drops, the problem is under the plenum.