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92 Talon Main Relay/ECU no signal to fuel pump even with new Main Relay

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nkosi

15+ Year Contributor
321
3
May 17, 2004
montreal, QC_Canada
I need some help with trying to figure out on my 92 talon tsi awd why when i turn on the the ignition key to run without starting the car i cant get the fuel pump to prime and run after the car is started . Here is how it went down and what i have done so far , i was driving the car home from the drag strip(didn't race the car) got off the highway the car was idling perfect at the traffic light. The light change to green i start moving then the engine was just wanting to die like its getting no fuel so i let go of the throttle and it dies immediately. While my gf calling the road side people i doing some trouble shooting to save my self a tow charge, i start by turning the key from off to run position and i don't hear the fuel pump priming as usual, so i check the relay of the fuel pump re-wire and that's working fine. Next i re-wire the pumps to direct battery power and the are working fine , i attempt to start the car and it fires up and starts to run with the pumps directly wired to power but not smooth and my AEM wide band gauge confirms it with readings 10.9-10.00 so its running rich but its running and i drive the car home which was about a 5 minute drive from where the car stalled. So thinking about what happen and how the car started running with the fuel pumps to direct power i came ti the conclusion the Main Relay needs to be replaced and i order one. I got the relay today and install it in the car and still i get no priming of the fuel pump when the key is at run before start, i try to start the car anyway and it starts but runs for about 10 secs and then dies no matter how much i step on the throttle. So i start checking all parts starting with Msd ignition box ,the coils , the transistor and the Main Relay itself and i hear it going on and of but still no fuel pump priming or running when the car is started. Next thing i do is check the wires going to and from the main relay to the ecu and they all seen to be working properly, Then with my tester light grounded i check a white/red wire at the Main Relay and at input 56 of the ecu and the fuel pump starts to run from the ground it gets from the tester light.

Now i lost as to what is going on with the car this has never happened before and everything seems to be working as they are supposed to but the car continues to start and run only for about 10-15 seconds and then it dies out. Again i wire the fuel pumps to direct power from the battery and start the car and it runs but not smooth with the Wide Band gauge saying rich at idle and when i press the throttle the wide band goes to 15-17. Is there a relay or fuse i need to change or there is something i didn't check please let me know any DSM wise man or anyone that had this problem and found the culprit thats causing the fuel pump not to prime and run continually when the car is started . Need some help badly on this one fella's .
 
Your post is confusing. Can't get the fuel pumps to run after the car is started? the relay is not energized unless the motor is spinning. Key to on does nothing you must be cranking to trigger the relay and of course once car starts its still spinning so fuel pump continues to fun.
 
Thanks for the responses fella's ... i tested everything including the pumps and everything is working as they should. I narrow it down to the AEM EMS series 1 it was not sending the signal to the fuel pump side of the main relay. During my testing to find the problem i applied ground to the output wire pin 54 white/red wire at the ECU that signals the fuel pump side of the main relay the pumps started to run, so its the AEM EMS and i sent it in for service. I have now got back the EMS and have to put it in the car to test to make sure everything is operating as they should.[DOUBLEPOST=1412103322][/DOUBLEPOST]If the problem persists im going to have to upgrade to series 2 EMS and sell the series 1.
 
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