07-22-2015, 08:05 AM
Join Date: Nov 2010
Location: Yorkshire, UK
Total Cats: 12
Fuel pump operation/logic/wiring
Hope someone can help with this.
1993 1.6 UK car.
Car runs with OEM ECU, with AFM, with emanage/bandaids. Would hold 11.5AFR at 8 psi no problem. Ergo - fuel pump 'OK' (if not necessarily great, aware of the voltage drop issues).
New aftermarket ECU fitted, AFM removed, double injector size. Car would start and immediately stall. No fuel pressure once running. Bridging to gnd at diag port enables car to run.
Ergo - something tells the pump to prime, but then doesn't keep it live when engine running.
What energises the pump to prime when you turn ignition on? And is this separate to what energises the pump once engine is running? How are these both switched on a standard car (I believe by the AFM sending a signal to the ECU and the ECU switching an output...?)