Bilge Pump Float Switch
Since you did not specify exactly what wires you employed to measure the 1.3 volts, I may make some redundant statements to the work you accomplished. Please accept my apologies. Nevertheless, both the manual switch and the float switch operate in the same fashion. In both cases, they complete a circuit to the pump, usually through the negative lead from the battery. Normally, a single wire is directed from the positive post of the battery to the positive input on the pump. Then there are two wires from the negative battery post, one to the manual switch and the other to the float switch. The wire from the manual switch then goes directly to the negative or manual input on the pump. “Closing” the manual switch completes the negative lead from the battery and therefore a completed circuit to the pump. The wire from the float switch then goes to the negative or float input on the pump. “Closing” the float switch completes the negative lead from the battery and therefore a completed circuit to the pump. It appears that since the pump operates by the manual switch, that the positive lead to the pump is ok and there is a problem in the negative lead from the battery leading to the float switch. This can be confirmed by applying a voltmeter to the negative lead going to the float and the positive lead that goes to the pump. Here I think you read your 1.3 volts. This should be about 12 to 13 volts depending upon the condition of your battery and the respective voltage drop occurring in the wire. The section of this negative lead that may be faulty may be just at the end near the float switch. Cut back about an inch to two inches of this wire and take another voltmeter reading to see if you get the required about 12 to 13 volts. If not, then you must track back the lead to where it connects onto either the negative terminal of the battery, some wire from the negative lead of the battery, or to some fuse either in line on the wire or at a fuse box. I doubt a fuse will be broken as you did indicate some voltage in the wires. At one of these connections, you may find the wire is badly frayed and nearly broken preventing full voltage from reaching the float switch. After repairing this, again check the voltage on the negative wire going to the float switch and the positive wire going to the bilge pump and see if you get the necessary about 12 to 13 volts. If not, continue onward with the process just mentioned. Good luck, I am sure you will be successful.
