06 turbo apex fuel presure problems

Add a fuel pressure regulator to the return line and see if that fixes the problem.

Might try checking your fuel pressure relay? On a stock Apex it is located underneath the left panel by your left knee. Between the clutch plate cover and the plastic. I'm assuming whomever has moved this wiring to the front of your sled so it runs toward the nose of the sled. This is where I have seen the wiring routed with turbo applications to keep the heat away from your midmount setup. Just changed one out tonight on a friends alpine kit and it solved the problem. His sled would run fine for a while, turned the sled off and it wouldn't fire. Wait a while and sometimes started, sometimes not. Not sure if this will help but worth a look!