Fuel pump wiring diagrams8/9/2023 ![]() ![]() So use a larger gauge wire for lower voltage drop.įor big pumps try 12 gauge, for smaller smaller 14 gauge. The diagram is color coded per circuit and only a few things may need to be said.įuel pump wiring for the RED circuit is generally going to carry a much higher current than the relay. This is the basic wiring diagram for SAFE electric fuel pump wiring. That's not what we want.īasic Safe Electric Fuel Pump Wiring Diagram The trick is we do not want the voltage from the ignition circuit to get into the starter circuit, if it did your cars starter would never stop working. Once the car starts, you will have oil pressure and the pressure switch will close completing the circuit and energizing the the fuel pump. In our case we want voltage to flow to the relay when the starter switch is closed, bypassing all the safety switches so the car can start. Positive voltage will flow from the non-marked end towards the white band end. Typically diodes have 2 leads one will have a white band next to it. Diodes are inexpensive, the part numbers listed are very common. If you have an EFI car your ECU may control the fuel pump, but if going the manual route use the diode to turn on the pump once you hit the start button (or key). If you car builds oil pressure fast and you have fuel in the float bowls you are good. If you are running a car with a carburetor you may get away without this part of the circuit. We can use one to help with starting where we have no oil pressure built up yet. Simplest way to describe it is a diode is one way valve for electricity. WTF is a Diode you ask (skip if you already know)? If needed later if you ever want a warning light, it's ready to go with the third wire My preference would be to get the harness for the PS118/PS122, which is a 3 wire unit but can be used on the 2 terminal types. ![]() The 3 Prong PS118/PS122 can replace the PS113/PS114 as it only has an additional circuit for a warning light. Check out the Wells site for selection.īoth the PS113/PS114 and PS118/PS122 have standard spade connectors that can save some money if you don't want to spend on the waterproof harness plug. They are available in long reach as well as a few other threads and style of connectors and fittings. These are available in either 1/8" NPT or 1/4" NPT so be sure what you order. The main thing we are looking for is 'NORMALLY OPEN' or 'NO', or a combination switch that has both a NO (Normally Open) and a NC (Normally Closed).įor most common applications the 2 Prong PS113/PS114 or 3 Prong PS118/PS122 will work. The Wells site has listings for many different style of senders. In poking around the web I found the Wells Vehicle Electronics site. These common ones will not work as we need a Normally OPEN switch that closes when oil pressure crosses some threshold. Their are many types of oil pressure switches, most common ones are normally closed. ![]()
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