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moboostin

Probationary Member
18
2
Feb 3, 2018
LA, California
I have a 95 talon with a 6 bolt swap that runs on an Aem v1 with a walboro 450. Everything worked fine till recently I connected a wrong plug to the idle switch sensor on the throttle body and it sparked.. Ever since than I was having issues with my fuel pump kicking on when turning the key. The fuel pump is rewired the relay is brand new and wired correctly. The issue here is the fuel pump will not kick on its own unless I connect the pin 30 (the 12v from the battery) to pin 86 the yellow wire from the fuel pump harness. When I run it for a few minutes like this and than shut the car off I can then connect everything back to the relay and than the fuel pump kicks on and functions properly with just the key and wired into the relay like it should. It works like this for a few hours than it will die again and I will have to jump the 2 pins again on the relay run the car for a little than shut car, connect the wiring to the relay and poof the fuel pump works on it own and the relay functions. Not sure why it doesn't kick on its own anymore.
 
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Find a "hot" 12v source that only comes on with the key and rewire the fuel pump rewire relay to come on with that signal. Not usually a hard thing to do. The heater blower fuse or any that come on with the key is a good location to find one.
 
I have a 95 talon with a 6 bolt swap that runs on an Aem v1 with a walboro 450. Everything worked fine till recently I connected a wrong plug to the idle switch sensor on the throttle body and it sparked.. Ever since than I was having issues with my fuel pump kicking on when turning the key. The fuel pump is rewired the relay is brand new and wired correctly. The issue here is the fuel pump will not kick on its own unless I connect the pin 30 (the 12v from the battery) to pin 86 the yellow wire from the fuel pump harness. When I run it for a few minutes like this and than shut the car off I can then connect everything back to the relay and than the fuel pump kicks on and functions properly with just the key and wired into the relay like it should. It works like this for a few hours than it will die again and I will have to jump the 2 pins again on the relay run the car for a little than shut car, connect the wiring to the relay and poof the fuel pump works on it own and the relay functions. Not sure why it doesn't kick on its own anymore.
You may have damaged the fuel pump relay coil or somewhere related to that. For some reason you are not getting the trigger signal for the rewired relay properly. So if I were you, I would try to inspect the fuel pump relay first and replace it if necessary. And then if it wouldn't solve, trace the wire from pin #86.
 
Kind of sounds like pin 86 is intermittent. If that is so, the signal to the rewire relay needs changed, even if it is just for "test" purposes.
 
Find a "hot" 12v source that only comes on with the key and rewire the fuel pump rewire relay to come on with that signal. Not usually a hard thing to do. The heater blower fuse or any that come on with the key is a good location to find one.


Will that bypass the MPI relay? I will give it a shot also will this take away from the 12v the pump gets from the relay? Thank you for your time and help!
 
Kind of sounds like pin 86 is intermittent. If that is so, the signal to the rewire relay needs changed, even if it is just for "test" purposes.
The relay for the pump rewire is literally brand new I guess I have to trace that wire and see what's up. Hopefully it resolves to something but either way what you mentioned with the key on seems like it'll just save me a headache LOL
 
You may have damaged the fuel pump relay coil or somewhere related to that. For some reason you are not getting the trigger signal for the rewired relay properly. So if I were you, I would try to inspect the fuel pump relay first and replace it if necessary. And then if it wouldn't solve, trace the wire from pin #86.

Ill test the relay and see what happens, I haven't yet but ill defiantly check that out if not than I will trace the wire! Thank you!!
 
Will that bypass the MPI relay? I will give it a shot also will this take away from the 12v the pump gets from the relay? Thank you for your time and help!
I think he suggested to do that with another switched 12v to the rewire relay pin 86, because pin 86 is supposed to have a switched 12v. But you actually did it already. You tested to connect the rewire relay pin 30 to pin 86 as you mentioned in the original post, that means you bypassed the factory fuel pump relay and applied 12v from battery, instead of a switched 12v. And then you could drive the car means the pump and the rewire relay are fine. The car ran fine while you were connecting the rewire relay pin 30 to pin 86 and all electronic things worked as it should, correct?

Ill test the relay and see what happens, I haven't yet but ill defiantly check that out if not than I will trace the wire! Thank you!!
If I understood this situation correctly, the rewire relay pin 86 doesn't receive 12v in some situation, "not always".
Which wire is connected to the rewire relay pin 86? You didn't mentioned that, but I assumed that you are connecting a blue wire from the harness to the rewire relay pin 86. And if so, it's from the factory fuel pump relay. So I suggested to inspect the factory fuel pump relay first. And if the factory fuel pump relay is fine, next check wires that are connected to the factory relay. Then if all wirings/connections are fine, I would start to suspect ECU is internally fried or another issue below.

Another thing I should ask is, can you connect to the AEM v1 via laptop when the issue is occurring? If you can't, your issue may be this one.
Next time when the issue is occurring, please do as below.

Turn off the key -> Disconnect all 4 ECU connectors -> Reconnect all 4 connectors back to ECU -> Try to start the engine.

If the engine would fire up with this method, you probably have a improperly wired or damaged relay, solenoid, sensor etc in somewhere.
Didn't you install some relay, solenoid, sensor or electronic device, just right before you started to have this issue? Would you mind to tell us what exactly you were doing when you made the idle switch sparked?
 
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I think he suggested to do that with another switched 12v to the rewire relay pin 86, because pin 86 is supposed to have a switched 12v. But you actually did it already. You tested to connect the rewire relay pin 30 to pin 86 as you mentioned in the original post, that means you bypassed the factory fuel pump relay and applied 12v from battery, instead of a switched 12v. And then you could drive the car means the pump and the rewire relay are fine. The car ran fine while you were connecting the rewire relay pin 30 to pin 86 and all electronic things worked as it should, correct?


If I understood this situation correctly, the rewire relay pin 86 doesn't receive 12v in some situation, "not always".
Which wire is connected to the rewire relay pin 86? You didn't mentioned that, but I assumed that you are connecting a blue wire from the harness to the rewire relay pin 86. And if so, it's from the factory fuel relay. So I suggested to inspect the factory fuel pump relay first. And if the factory fuel pump relay is fine, next check wires that are connected to the factory relay. Then if all wirings/connections are fine, I would start to suspect ECU is internally fried or another issue below.

Another thing I should ask is, can you connect to the AEM v1 via laptop when the issue is occurring? If you can't, your issue may be this one.
Next time when the issue is occurring, please do as below.

Turn off the key -> Disconnect all 4 ECU connectors -> Reconnect all 4 connectors back to ECU -> Try to start the engine.

If the engine would fire up with this method, you probably have a improperly wired or damaged relay, solenoid, sensor etc in somewhere.
Didn't you install some relay, solenoid, sensor or electronic device, just right before you started to have this issue? Would you mind to tell us what exactly you were doing when you made the idle switch sparked?
I see what your saying, that makes perfect sense. Yes everything worked perfectly when I connect those two pins but I will take your advice and go ahead and check the fuel pump relay, the wiring and connections today and yup the blue wire from the harness is connect to pin 86.
As for the ecu yes I can connect when the issue occurs but okay I will give that a shot today as well! Thank you!!!

As for what I did, I was having an idle surge so I went on the forums and I read up on the fast idle sensor. I saw mine was unplugged apparently I connected the wrong one and that pin off the throttle body sparked and the car shut off on the spot. Ever since than its been acting like that. I uploaded a picture its the pin circled in red that I tried connecting too.

Again, thank you so much for your help. Highly appreciate it
 

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