VN VP VR Fuel Pump
Page created by T Dec 18th 2008:
[Image:Vn_efi_pump_mounted2.jpg|thumb|VN Fuel Pump
VN VP VR Fuel Pump:
VN VP VR Fuel Pump Circuits:
bf6379 on Wed, 17/12/2008 - 15:10.
A lot of people think that VN-VP-VR's use the oil pressure switch as the only source of power to the fuel pump. This is not correct.The oil pressure switch is only used as a back-up circuit in case the ECM/PCM has a failure. In normal operation the fuel pump relay is controlled by an output from the ECM/PCM.The oil pressure switch circuit on the VR's is different to the VN/VP's.VN/VP's have the oil pressure switch contacts wired directly in parallel with the switching contacts of the fuel pump relay. If oil pressure is present, then power will be supplied to the fuel pump regardless of the state of the output of the ECM. Once the engine is running, you can remove the fuel pump relay and the engine will keep running.VR's use a different type of fuel pump relay. It has a normally closed (NC) contact and a normally open (NO) contact. When the relay receives a signal from the PCM, the NO contacts close and pass power to the fuel pump. The oil pressure switch is wired to the NC contact. The only time the oil pressure switch can supply power to the fuel pump is when the relay is de-energised (in the case of a PCM failure). Because the back-up circuit actually passes through the fuel pump relay, if you remove the relay the engine will stop.If someone has swapped the fuel pump relay in a VR with a standard 4-terminal relay (as used in VN/VP), then the oil pressure switch backup circuit will not work. VR's should have a 5-terminal relay.Brett.