I'm working on a LS1 with a leakdown problem. The FSM says to isolate the injectors and pump/regulator using a tool J37287 which looks like a cut off valve that connects inline. I've been trying to find that tool or an alternate part number with no luck. Is there anything you can do without the tool? Other sites have said to clamp the line but I don't think that's such a hot idea with a hard plastic line..

IIRC Isnt there a potrion of the line thats SS braided?
If so clamping it there wont hurt.

Well that J tool is basically a block off tool that take's the place of the fuel filter.once you have it hooked up you attach a fuel pressure guage and it's a way to test if your fuel pump is holding pressure or not... once it's blocked off you prime the system and if it holds there you know the leak is somewere at the engine. After that you just need to figure out if it's an injector or a cracked high pressure line.

Since no one's talking about them anywhere I figure you don't need em. I'm getting ready to find out~~~