I didn't buy one because it cost too much.
If you already know this - I apologize.
The circuit that provides battery voltage to the in-tank fuel pump is 654. It feeds off of the master power switch, routes through a cannon plug and then on to the fuel pump.
If you have already done these voltage or continuity checks, I apologize.
You can start with voltage checks at either end and work your way through. I like to start at the component that is supposed to work.
Turn the master power on and set your voltage tester to 30, 60, or 100 VDC (higher than 24volts). Ground the negative lead on a clean part of the frame. Touch the positive lead to the wire feeding the fuel pump.
If there is voltage either the fuse is blown, the pump is faulty or the tank isn’t getting a good ground through the mounting brackets.
If no voltage then trace that wire back and look & feel for brakes or unintentional grounds.
With the MSTR PWR on You can then text circuit 654 at the cannon plug (most likely on the firewall). If you have Voltage getting to circuit 654 but it is not making it to the fuel pump there is a break in the wire from the fuel pump to the cannon plug.
If you are not getting voltage through the cannon plug poke your voltage tester lead into the opposite cannon plug side that holds 654 coming from the master power switch. If you are getting voltage to the cannon plug but not through it inspect the cannon plug pins and sockets for damage (burnt) or pushed out not allowing contact. Sometimes someone will try to force the cannon plug in toplace and it’s not lined up. That could bend or break or push the pin or socket out to the point it will no longer make a connection.
If you are not getting voltage in the MSTR PWR switch side of the cannon plug trace that wire to the master power switch looking for a break or unintentional ground.
Finally, you can test to make sure the master power switch is providing voltage to circuit 654.
To verify an open circuit by checking resistance - be sure to remove all power from the circuit. Additionally, disconnect the cannon plug so you can read one leg of 654 at a time. If you don’t isolate each leg your reading could be influenced by parts / components in the circuit.
This seems like a lot of work & testing but it isn’t. Most circuits fail or have human induced issues at one end or the other or at connections along the circuit. Believe it when I tell you I’ve come across oxidized and corroded wires in the center of a circuit and could only find it by touch or by probing that wire every couple of inches until I no longer had a reading. When the reading stopped I knew the break was right there.
It has got to be something simple.
