One such part of the car engine is the fuel pump relay. When a relay is defective, it is usually because of a bad coil or bad connection. The main relay in a vehicle controls the fuel pump and supplies power to the injectors. This test result lets you know that the no-start problem is caused by a lack of fuel from the fuel pump. How to diagnose a bad fuel pump relay Visual inspection. Consult your owner's manual or a service manual to find the location of your fuel pump relay. With the help of this ‘How To’ tutorial, I'll show you how to do it using only a multimeter. A fuel pump relay functions primarily to maintain a consistent voltage supply to the fuel pump. The car's uninterrupted proper functioning is so much dependent on the fuel pump relay and its related parts, that it is imperative for you to understand how to check a fuel pump relay. There's a pretty simple way to tell if your main relay is affected. I recommend that you take one more precaution, before condemning the fuel pump as bad, and this is to make sure that the fuel pump is getting 12 Volts as the engine is cranking. Are the battery connections clean? Function. Fuel Pump Relay - Function And Testing Procedures The fuel pump relay is activated whenever the ignition is turned on. A car's fuel pump relay turns on the fuel pump when the motor runs. If the fuel pump relay fails, the fuel pump will receive no power and will not operate, thus it will be silent. With the relay out of the coupler, use a jumper wire between the … The fuel pump relay supplies electricity to power up and power down the fuel pump. How to Test the Main Relay in a Honda . Variety of electric fuel pump relay wiring diagram. If the relay, ECU, and wiring are all OK, the bulb will light up when you crank the starter. Knowing how to test a Honda main relay can help you better pinpoint the cause when an electrical issue arises. Simply turn on the vehicle and see if it continues to run. It shows the elements of the circuit as streamlined shapes, and the power as well as signal links in between the gadgets. Go back to basics, does the battery have a full charge to run the starter? The Latest ASE Test Tips Entry. To check both operations, remove the relay by pulling it out of its socket. The fuel pump relay has nothing to do with the starter motor not running- the starter should turn the engine with or without a fuel pump or fuel pump relay. In case of any fuel injection problems, it is customary to run a test on the relay, to determine if the source of the problem is that component. Check your owner's manual for the location of your fuel pump relay. A wiring diagram is a simplified standard photographic depiction of an electrical circuit. In about 20% of the cases, this lack of fuel could be caused by a blown fuse, a bad fuel pump relay, a triggered fuel pump interrupt switch etc. This test result usually confirms that the fuel pump is bad (in about 80% of the cases) and replacing it will solve the no start problem but not always. A broken fuel pump relay causes a malfunctioning pump, starving the engine of fuel. A relay works in a similar way, but instead of you reaching into the relay to flip on the internal switch directly, you energize a control circuit that connects to a coil inside the relay — this happens to the fuel pump relay when you turn the ignition switch to fire up the engine, for instance. Always start with a visual inspection first before moving on to other tests, which will be specified below. Testing the fuel pump for operation. Location and Function A fuel pump relay is a vital cog in the car's fuel injection system. Fuel Pump Relay - Function And Testing Procedures The fuel pump relay is activated whenever the ignition is turned on. Scan Tool Online Pre – Test Examination Answer Key; Scan Tool Online Pre – Test Examination; FREE ASE PREP: Throttle Position Sensor; Fuel Pump Relay; ASE A6 Wiring “Sensor” Schematic These accessories can range from the main computer PCM (powertrian control module), radiator fan, fuel pump, door locks etc. The ignition or powertrain control module (PCM) usually controls the fuel pump relay. Location. The engine control module (ECM) uses the fuel pump relay to control when the fuel pump is on. The ignition or powertrain control module (PCM) usually controls the fuel pump relay. If you aren't sure that the pump is good, disconnect the fuel pump connector at the fuel tank and connect a headlight bulb between the larger wires (green and brown I think). CASE 1: The fuel pressure test gauge recorded 56-62 PSI after swapping the relay.This test result confirms that the fuel pump relay is defective and needs to be replaced.
The fuel pump relay is what turns on the fuel pump when you start your car and powers it down when you shut off the ignition. In case of fuel injection systems, one of the most important parts is a fuel pump relay. A fuel pump relay does not have many parts to inspect, so worry not. The engine may stutter, stall or not start at all. Once activated the relay connects an electrical supply to a particular accessory.