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What Triggers the Fuel Pump Relay?


beaverbikes

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Hello, new guy here. We have an 89 5.0 EFI motor in an 87 Ranger. Just started trying to figure out the wiring, have spent a few hours with older posts here. Using the harnesses from the donor Crown Vic, and the original Ranger chassis wiring. We now have it to where it'll crank from the starter/ignition switch, and has spark while cranking. So, its on to the fuel system. I haven't got wires to and from tank figured out yet, but here's my question..........I got juice to the fuel pump relay, but not out of it. Big yellow and orange wires, whichever one that should take off to the inertia switch does not have power when I crank the engine.

Sorry so wordy, this looks like a great forum, anyone has an idea.....Thanks!!
 


Teddyzee

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Pin 22 from the V8 ecu will trigger the Ranger fuel pump relay.

If you Ranger originally had a FPM circuit, this will be joined to pin 19 of the ECU.
That is, if the donor V8 is mass air. If it is Speed Density, there is no pin 19...

In this case, you with need to ground the original Ranger FPM circuit.

Was your truck originally EFI? What order did your truck work- ECU-Inertia-FPrelay-FP, or ECU-FPrelay-Inertia-FP?

My truck is/was the the second way, Fox body Mustangs are the first way. Doesn't really matter, just helps with trouble shooting.
 

beaverbikes

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Thanks a lot Teddy. You are a little bit over my head, but that's okay I'm gonna learn fast. We're using the whole front harness from the donor Crown Vic- that includes its fuel pump relay, ECM relay, computer, etc. Never have found a wiring diagram actually showing anything about the pump itself. I could get a hot wire back to the pump from the relay to get me started, but haven't been able to get the relay to switch on. Been trying to learn where the wire coming back from the pump should hook in..........maybe that wire needs to be figured out for the computer to do its thing.
 

Teddyzee

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See if this can help. It's some info from Joel @ sbftech.com




The ECM generates an initial ground pulse (FP signal at pin 22) to activate fuel pump relay when ignition key is turned on (pump prime). Subsequent FP pulse generation will depend on the presence of the PIP pulse, generated by the stator sensor/TFI module when engine is cranking or on.
The FP signal (FP relay triggering), wire, and relay coil are known as / referred to as the PRIMARY circuit.
At the same time the FP pulse is generated the ECM monitors a 12-vdc signal, from the FP relay, to confirm the fuel pump is receiving power, or its ON/OFF status at pin 19 in the ECM. This signal is identified as the Fuel Pump Monitor (FPM) 12-vdc signal, also identified, or referred to as the SECONDARY circuit.


http://sbftech.com/index.php/topic,29871.0.html

The PIP is the sensor inside the distributor, TFI is on the outside of the distributor, or remote and wired to the distributor, in case you weren't familiar with the terms.
 
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bobbywalter

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pin 22 is the arm for the ground side of a relay for any eec4 to run a fuel pump.


for a monitor...it can be either 19 or 8 or nothing on a stang pcm.


the vic harness depending on what year can be a pia, i have had many sent to me where the sender thought it was a stang harness...and its much more work to clean up verse an actual stang harness when a guy is following stang instructions.


i actually prefer the vic relay systems though from 88 on.


if you leave the harness intact you only need to hook up the crank run power/crank power to it which is red light green to red light green and red light blue to red light blue...which you see to have under control.

theres a small 3 wire stub, near the pcm connector, one of those goes to pin 22 and the eec interface, it is the one you want to connect to the ground side of your fuel pump relay. usually they are tan with light green tracer....the dvom will find it....check it that way no matter what.
 

bobbywalter

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FORD mostly
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V8
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Automatic
2WD / 4WD
4WD
Total Lift
sawzall?
Tire Size
33-44
My credo
it is easier to fix and understand than "her"
Hello, new guy here. We have an 89 5.0 EFI motor in an 87 Ranger. Just started trying to figure out the wiring, have spent a few hours with older posts here. Using the harnesses from the donor Crown Vic, and the original Ranger chassis wiring. We now have it to where it'll crank from the starter/ignition switch, and has spark while cranking. So, its on to the fuel system. I haven't got wires to and from tank figured out yet, but here's my question..........I got juice to the fuel pump relay, but not out of it. Big yellow and orange wires, whichever one that should take off to the inertia switch does not have power when I crank the engine.

Sorry so wordy, this looks like a great forum, anyone has an idea.....Thanks!!

there should be two smaller wires, one red, the other like mentioned earlier tan with green------the two fatties one should be yeller or black yellow and always hot.....the other orange light blue should head to the inertia switch.


of the two smaller, the red should be hot when the key is on...sometimes its red/blacl black/ pink or plain brown...or a few other colors.....i dont know why they can be different colors just know sometimes they are.

so that leaves one choice....and that goes to pin 22.
 

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