Jon.C Posted May 22, 2017 Report Share Posted May 22, 2017 Hi,i have an g4 plug in ecu in my evo.suddenly my fuel pump just start to go when battery is connected and the ecu i not powered up.what i found is that as soon the battery are connected and without any power on the ecu it grounds all of the aux output. also what is strange is when this happens (the pump runs) i switch on ecu the pump stops for 1 sec and then starts again in prime mode (2sec) and stops. and will be stopped until i turn of either ecu ore main power supply.i tried different outputs and only one i named fuel pump at the time.the relay is hooked up like this: 30 and 85 to positive. 86 as a signal from ecu. 87 to pump positive.and for the record i have checked earth and power supply cables.i fear the worst scenario now, broken ecu. could anyone give me a pointer here? Quote Link to comment Share on other sites More sharing options...
Brad Burnett Posted May 22, 2017 Report Share Posted May 22, 2017 seems to be power back feeding due to improper relay wiring. run pin 85 for the relay to +12v SWITCHED source.That would be my first thought. Quote Link to comment Share on other sites More sharing options...
Jon.C Posted May 24, 2017 Author Report Share Posted May 24, 2017 I tried that. I doesnt make a difference. the same happens without fuel relay. Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 25, 2017 Report Share Posted May 25, 2017 Your symptoms still very much suggest a back feeding aux. Is the car wiring stock apart from the fuel pump? What version evo? Does it have an alarm or aftermarket immobilizer etc? Was there any event related to when this started happening? - i.e flat battery, jump start, wiring changes, any accessories added? Quote Link to comment Share on other sites More sharing options...
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