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  • 2015 - 2023 (S550) Mustang -General/Talk

15' GT Pumps stay running with key on

  • Thread starter Thread starter White5Hoe
  • Start date Start date Sep 8, 2023
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White5Hoe

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Sep 8, 2023
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Sep 8, 2023
#1
  • Sep 8, 2023
  • #1
As the title says, my fuel pumps stay running non stop with accessory power on when it should only prime for about 1-2 seconds. I have a VMP return style fuel system, so it has it's own wiring for power and ground however, the fuel system relays are trigged by the stock wiring/relay in the engine compartment. When I unplug the fuel pump relay in the engine bay the pumps cut off when accessory power is on. The pumps will shut off when I key off like normal. I contacted my tuner and thought maybe they had the pumps running all the time with key on but they said no that's not the case. Any ideas as to what would be causing this? I've swapped out the stock relay and nothing changed, so I'm just a little lost as to what would be going on here. Hopefully it's not a bad computer.
 

90sickfox

Wasn't a pretty sight...and I've got big hands
SN Certified Technician
Mar 2, 2015
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Sep 8, 2023
#2
  • Sep 8, 2023
  • #2
The factpry computer looks for a fuel pressure reading. My 19 would prime the fuel pump when I opened the drivers door without the ignition on at all. It could be a programming thing. You'd need a scanner or forscan so you can see what the computer is commanding and what inputs it's receiving.
 
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