help jrichker
- Thread starter ZephyrMotorspor
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I will take a little stab at this - Jrichker will be able to help a lot more. The injectors get a constant (albeit with the key on only) 12 volts. The computer modulates the ground pulse to excite the squirters.
It seems to me that the EEC relay is what supplies that 12 volts to the injector harness. But said relay supplies 12 volts to many systems, so if other things are working (your fuel pump is priming, etc) then I would trace the 12 volt feed from the injector harness backwards. Look for the wire to be pinched, cut, eaten by pack rats, etc.
Like I said, wait for JR to reply - he will be tons more helpful than I can be.
Good luck.
It seems to me that the EEC relay is what supplies that 12 volts to the injector harness. But said relay supplies 12 volts to many systems, so if other things are working (your fuel pump is priming, etc) then I would trace the 12 volt feed from the injector harness backwards. Look for the wire to be pinched, cut, eaten by pack rats, etc.
Like I said, wait for JR to reply - he will be tons more helpful than I can be.
Good luck.
Here's a diagram....
Diagram courtesy of Tmoss & Stang&2birds
Hissin50 is correct, the computer does not source any power for any
actuator or injector. It provides a ground to complete the circuit. If you have
no 12 volts at the injectors with the key in the Run position, you have wiring
problems.
Start by carefully studying the power feed to the injectors and noticing
where they get their power. Once you have determined the power is OK,
start looking at the wiring and connectors. The 10 pin salt & pepper shaker
connectors are one place to check.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif
Diagram courtesy of Tmoss & Stang&2birds
Hissin50 is correct, the computer does not source any power for any
actuator or injector. It provides a ground to complete the circuit. If you have
no 12 volts at the injectors with the key in the Run position, you have wiring
problems.
Start by carefully studying the power feed to the injectors and noticing
where they get their power. Once you have determined the power is OK,
start looking at the wiring and connectors. The 10 pin salt & pepper shaker
connectors are one place to check.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif
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Black1987Stang
Active Member
Just checking but you did have the key on when u checked for the power right? What i always do is put negative black lead from voltmeter on negative battery terminal and red lead on the injector wire, i check both just for memory. and i always get 11.9v when i check it at the computer and so i dont have to take the intake off. Im sure one of the things Jrichker will say to check is the salt and pepper shakers, i forget which one has all the injector wires in it. but u can check for power and go from there. How did this happen, just didnt start one day, or after a rebuild or something?
From the beginning...
I was driving to the paintshop---rpm drops at a stop light, dies---towed home by dad's ranger---sat---sat--sat---replace dist. cap, rotor, and TFI module---sat---sat---sat---installed bett. cut-off switch (unrelated, just figured that if i was gunna be working on it alot, it'd be easier than having to disconnect the batt. constantly)...
since then i've checked the injector wires (pulled entire upper manifold off and checked them fully), replaced WOT relay (had been melted b/c it was resting on the header), and replaced fuel pump relay (matter of procedure just to make sure).
Again---Getting spark, getting fuel to schrader valve, fuel pump works, starts with ether (for a few seconds), injector wires are not getting 12V. Injector wire integrity is good.
I was driving to the paintshop---rpm drops at a stop light, dies---towed home by dad's ranger---sat---sat--sat---replace dist. cap, rotor, and TFI module---sat---sat---sat---installed bett. cut-off switch (unrelated, just figured that if i was gunna be working on it alot, it'd be easier than having to disconnect the batt. constantly)...
since then i've checked the injector wires (pulled entire upper manifold off and checked them fully), replaced WOT relay (had been melted b/c it was resting on the header), and replaced fuel pump relay (matter of procedure just to make sure).
Again---Getting spark, getting fuel to schrader valve, fuel pump works, starts with ether (for a few seconds), injector wires are not getting 12V. Injector wire integrity is good.
Note: all the following tests are done with the key in the Run position and the battery connected as usual.
Remove the passenger side kick panel and then disconnect the computer connector. You will need a 10 MM socket & ratchet to do so. Look for 12 volts on pins 37 & 57 of the computer connector.
No 12 volts, then look for 12 volts on the black/orange wire on the EEC relay located above the computer. You may find it helpful to remove the passenger side dash speaker to gain some eyeball room.
No 12 volts on the black/orange wire, then you have a bad fuse link or bad wiring from the fuse link to the EEC relay. The fuse links live in a bundle next to the starter solenoid.
Good 12 volts on the black/orange wire, then look for 12 volts on the red/lt green wire on the EEC relay. No 12 volts there, you have a bad ignition switch or bad wiring from the ignition switch to the EEC relay.
Next turn the key to Off and set your meter to resistance to measure low resistance connections.
Measure the resistance between pins 40 & 60 on the computer connector and ground. You should see less than 1 ohm. More than 1 ohm means that the coputer primary power ground is damaged or missing. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
Remove the passenger side kick panel and then disconnect the computer connector. You will need a 10 MM socket & ratchet to do so. Look for 12 volts on pins 37 & 57 of the computer connector.
No 12 volts, then look for 12 volts on the black/orange wire on the EEC relay located above the computer. You may find it helpful to remove the passenger side dash speaker to gain some eyeball room.
No 12 volts on the black/orange wire, then you have a bad fuse link or bad wiring from the fuse link to the EEC relay. The fuse links live in a bundle next to the starter solenoid.
Good 12 volts on the black/orange wire, then look for 12 volts on the red/lt green wire on the EEC relay. No 12 volts there, you have a bad ignition switch or bad wiring from the ignition switch to the EEC relay.
Next turn the key to Off and set your meter to resistance to measure low resistance connections.
Measure the resistance between pins 40 & 60 on the computer connector and ground. You should see less than 1 ohm. More than 1 ohm means that the coputer primary power ground is damaged or missing. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
Take a break and collect your thoughts. Write down what you have already done in a 1, 2, 3, 4 kind of list. Follow the path I have laid out and you will find the problem. It isn't that hard. I have seen threads stretch out for 30 or more posts before the answer was finally found.
hey i found three somewhat large gauge (16-14) wire all black/white stripe, melted together and laying around by my solenoid. i cut-stripped-and crimped them to a ring connector, and for some reason i touched it to the solenoid post closest to the front of the car, and i heard a relay click...i think maybe the WOT relay next to the MAF sensor. there's another one that is small gauge and black/yellow stripe...what is it?
ZephyrMotorspor said:
Autozone wiring diagrams see http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) &
Stang&2Birds (website host) for help on 88-95 wiring
The black white wires are the power ground for the computer.
They are supposed to be connected to the negative
battery cable pigtail ground that bolts to the body.
It is not good that you connected them to the + side of
the battery.
My impression is that you haven't read the post I made last night at 10:32. If
you had followed it, there is a very good chance you would be driving the car
by now.
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