Yippee! One in a row!
I went home concerned that my explanation was not adequate about those wires. One of them is not a positive wire. That is a single wire that goes from the pump to ground. It is the pump's ground wire. We have not done anything with its positive wire. The secret I eluded to was that when there is a break anywhere in the circuit, like you had, when twelve volts is switched onto it, you will see that full twelve volts all the way through the positive wire, (like normal), through the pump motor, and through the negative wire all the way up to the break, then zero volts everywhere after the break. That is why I said to test for twelve volts on those wires, and it should be there for one second when turning on the ignition switch, and again during cranking. That would simply prove you found the ground wire, and it was not grounded.
This is a real simple circuit in that it has just two wires and two connector terminals, so my testing might seem overly-involved. It is when there are three, four, or five connectors in the harnesses before you finally get to the motor or light that this becomes a valuable test to narrow down the location of the break. Regardless, I can go home now knowing you are back on the road.
Friday, September 15th, 2017 AT 7:33 PM