'96 fuel problem

When the engine is warm the fuel shuts off. It's a 3800. The pump seems to be okay. runs good cold but when its warm it won't start and recently quit while running when it warmed up. I don't think it is the fuel pump itself or filter as the engine temp would not effect it. I have been unable to find a relay, though I have found the relay box but fuel pump is not included in there. Any thoughts?

J.C.