OK there are only two things that will make it come on. faulty switch in your tank. Or a short in the wiring. IF you have a manual the service proceedure in in Chapter 7 page 34.
Basically to test it you need a test light.
Remove the fuel pump assembly and test the switches. They should both be on.
Submerse thelower one in water and the one lead should turn the light off and the other should be ON.
Submerse the upper one in water and both leads should be off.
This should get you started.
Slo