How to Troubleshoot a Fuel Pump Fuse. Fuses are designed to allow a maximum amount of current to flow through them based on the normal electrical needs of an electrical component. If a component operating in its normal capacity requires 12 Volts and 1 Ampere, then a fuse that permits that amount of electricity through it is used in that application. Ultrasonix EC9-5/10 Ultrasound Transducer Probe Endocavity If something goes wrong with the device causing it to draw more power than normal, the fuse melts (blows) to prevent the component from overheating and catching fire. This is especially important with fuel pumps. Fuel pump fuses are actually relays with set resistance.
Some fuel pump relays have more than just two wires, and may include up to six in some applications, depending on how the fuel pump is wired and what different kinds of voltages it needs. In such a case, a diagram may be needed to see how the given relay works,Ultrasonix EC9-5/10 along with which tabs have power coming in and which tabs have power going out and in what amounts. Such a diagram is called a "schematic diagram" and it will show you which tabs to test with your multimeter. Check with your local automotive center for information about obtaining such diagram for
Since fuel pump relays have a mechanical switch inside, the simplest way to check if one is working is to do, what is called in mechanic circles, the "hear test."Ultrasonix EC9-5/10 Relays make a light clicking sound when activating as the ignition switch is turned on. If this sound isn heard, try swapping the relay with a new one.
Never replace a fuse or a relay with one of a larger capacity, especially in the case of a fuel pump that keeps blowing the device. If more electricity is allowed to flow to a faulty fuel pump, fire or explosion may result if the problem is caused by an electric "short," where two wires are crossing together somewhere between the fuse box and the pump itself.
