There should already be enough listed on this thread for you to resolve your problem. Please reread all of the post until you understand it all and check what is mentioned.

Either Pin 85 does not have ground when the engine is off or Pin 86 is not getting power. Did you check to make sure the relay was making contact with pins 85 and 86 as mentioned earlier? Check the switches function using an continuity tester on the connection that Iceman posted a pic off. Then check the wiring and the condition of the contact on the plug that connects to it.

 

I had the same problem and after dancing around for a while I solved the problem in a different way.
Since it is true that the system is a loop, the problem is not that the pump is running more than it should. The problem is that, in the event of an accident (especially if you end up upside down) and subsequent fire, a ruptured fuel line would give new meaning to the phrase "fire hose".

I bought a cheap inertia switch (I think about $50 bucks) installed it in the wiring to the fuel pump and problem solved. I got the idea either from a thread here or on Pelican.