Fuel pump problems

[Patty28715]

1987 ford ranger. Replaced motor. Both ran fine before switching. Hooked all ground wires. Fuel pump wil come on and pressurize but wont start. When we put test light on the pulse side of injectors it wiil start and run until it runs out of gas. We are stumped and need advice on what to do to fix this. We tried switch under glove box and changed it no luck. Changed computer. Changed both fuel pumps. Checked fuses. Help!!!!!!!!