[goser]

'01 Blazer: since I bought it a few months ago the sending unit has only worked intermittently and it's been hard to start. Once it's going it runs fine. At one point the fuel pump was whining so loudly for a few days that I could hear it over the engine at the front of the truck. Fuel pressure gauge showed low 50's psi on key on, then immediately fell back to zero. It seems pretty obvious that the pump is inches from death, but the instant leakdown got me wondering if there could be a leak somewhere or a bad pressure regulator as well. I don't see or smell any gas under the truck. Before I drop the money on a delco pump, is there a way to determine if the problem is solely in the pump? I remember something about testing the pressure while blocking off the return line, but I'm not sure which of the other two lines (or both?) are returns. I'm also not sure how to block them off without damaging them. Thanks for any advice you can offer.