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1989 Eddie Bauer 5.0
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48 Posts
Discussion Starter #1
As I prep for replacing the injectors and pressure regulator in my 1989 5.0( runs rough and sat up for 2 years without moving) I thought it would be a good time to try and figure why my fuel pump runs continuously. I thought that a fuel pump, once keyed to run (before starting) would build pressure, then stop. This one doesn't. The P.O. stated they replaced the fuel pump. If I correlate that with the story that the gas gauge started working when they replaced the fuel pump, and the fact that it sounds and feels like the fuel pump closest to the motor on the frame is running, I can assume they replaced the fuel pump in the tank, and not the high pressure fuel pump. Previous owner did some sketchy repairs that I'm discovering as I delve deeper into this thing. Including blocking a vacuum line on the plenum. IDK where Ford wanted it to go. Why does this thing run constantly?
 

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Super Moderator
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14,885 Posts
you've got an electrical issue somewhere..start with the easiest first and check the relay, it could be sticking or you could have a short to ground in the relay/control side. might also want to pop open your EEC and check for any corrosion in there.
 

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1989 Eddie Bauer 5.0
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48 Posts
Discussion Starter #4
you've got an electrical issue somewhere..start with the easiest first and check the relay, it could be sticking or you could have a short to ground in the relay/control side. might also want to pop open your EEC and check for any corrosion in there.
I hooked up an OBD1 scanner tool. It activated relays when you first start it. I would think it would notice that, but that's a good place to start eliminating possibilities. How does it normally know when to stop?
 

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Are you asking how the fuel pump knows when to stop running? I believe it's controlled in the EEC.
 

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Registered
1989 Eddie Bauer 5.0
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48 Posts
Discussion Starter #6
Are you asking how the fuel pump knows when to stop running? I believe it's controlled in the EEC.
Something has to trigger that signal, though, right? The EEC has to get a certain pressure reading or some kind of input to toggle the relay on or off, I would think.
 

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Premium 4 Lyfe - Way Back Staff
'95 XLT: 5.8, MAF, E4OD, 4.56's, 6" on 33's
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You need your stats in your profile or your signature line, so they show up with your comments and nobody has to search them down to answer your year specific questions.

I had the PCU/EEC/ECU or whatever... gone bad, fuel pump won't stop issue in my '95 awhile back...
 

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Registered
1989 Eddie Bauer 5.0
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48 Posts
Discussion Starter #8
You need your stats in your profile or your signature line, so they show up with your comments and nobody has to search them down to answer your year specific questions.

I had the PCU/EEC/ECU or whatever... gone bad, fuel pump won't stop issue in my '95 awhile back...
Thanks for the reminder. I was having trouble doing it on my phone. Got it done at the old home compooter! Appreciate the link too!
 
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