5.0L (1979-1995) MustangTechnical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.
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My fuel pump won't turn on when I turn the key to the on position. I have researched the fp relay and replaced, replaced the fp and the solenoid and fixed the gr/yl wire which changes to or/bl before getting to the solenoid. The previous owner rigged the pk/bk wire coming out of the fp relay to have constant power through the fuse panel, this caused my fp to run constantly and to prime constantly. I put the pk/bk wire back where it was suppose to go but now I don't know where the pk/bk wire goes. I think it goes to the ignition switch but not 100% sure. I have pics of what I'm talking about. Any help would be appreciated
Thanks for the responses. I have actually taken the dash off at this point. Not only because of this issue but I have to do a heater core replacement, alarm system removal, just seeing what the h3ll others have done, etc. The most recent discovery is the lack on connectivity between the pin 19 wire (pk/bk) at the EEC and the wire at the fuel pump relay also pk/bk. Is there a fuse, fuse link, connector etc between the EEC and the quick connect that is behind the fuse panel on the drivers side?
Bubba 95SN, I already looked at those diagrams, and multiple others, none show what I wanted to know, hence the second question. Either way, I've test multiple options and now am at a lose. The only two things not replaced at this point are the grounds for the vehicle and the EEC. These are the only two options left. My EEC is giving 6 volts when the key is in the ON position. It has 7 volts when the engine is on. I have tested the grounds at the solenoid, under the EEC, block to frame, and a couple of others, all are tight, any appearances that looked shady to me, such as a junk splice have been redone so I've all but ruled out ground issues. If the EEC is bad I would think pin 19 would get no volts and other things would be wrong with the vehicle. Any suggestions, rumors, outbursts, etc???
Thanks mattdel. I've looked at veryuseful.com and multiple other diagrams. These are great for general knowledge of where the wire runs. However, they do not tell all the connectors, grounds, splices, etc that I need to diagnose. For instance one diagram shows two pk/bk wires coming out of the fp relay, this is false, there is actually a splice just under the carpet to the right of the drivers seat if facing from the front of vehicle. This splice had been taken apart in the past and put back together loosely by a previous owner. I reconnected it properly but this was not the answer to why my fuel pump does not turn on when I put the key to the acc/on position.
I did find out the EEC is only suppose to have 6 to 7 volts at pin 19 at any given time. Ford technician from church told me. Next step for him would be the CCRM....
"If it flies, floats or f#cks, rent it"
K, so here's what my diagrams show. (All references to LH/RH assume you're in the drivers seat.)
The pink/black wire that runs from PIN 19 of the EEC to PIN 5 of the relay has two connectors along the length of the wire.
C207 is inside the LH cowl panel.
C213 is inside the RH cowl panel.
Check for continuity between PIN 22 of the EEC (Tan/Light Green) and PIN 1 of the FP Relay.
2 connectors along that circuit as well, to check for incase of no continuity.
C203 again inside the LH cowl panel.
C110 is LH rear of engine compartment.
The Orange/Light brown wire on PIN 3 of the relay has an 18 gauge brown fuseable link.
Make sure the red wire incoming to the inertia switch has 12v.
Still, nothing...... at fp relay, Power to gr/yel wire constant 12v, red wire 12v when key turned to acc, pk/bk wire 6v when on acc, tan/bl wire 0v at all times....
Under the hood the tan/bl wire is not connected to anything, it is sitting right next to the self test connecter with multiple holes, this is the way the tan/bl wire should be correct? I couldnt find anything obvious to connect it to so I assume.
"If it flies, floats or f#cks, rent it"
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