EEC test + rain +fuel pump = what?

james51381 · Apr 20, 2004

EEC test + rain +fuel pump = no workie

working out some codes the other day, and noticed that the connections from the EEC for the code reader where gapped pretty wide. So I took some needle nose pliers and closed them up a bit. Hooked up the code reader (off) and turn the ignition. As soon as I did, I heard sparks and then a little bit of smoke coming from where the code reader was. I unplugged it and tried to start the car............. No fuel pump prime, and no more fuel pressure. I changed the relay under the seat. I also checked the inertia switch (it has a little white button on top right?) and it wasnt up as high as it could go. I can push the button down maybe a couple of centimeters. On both sides of the inertia switch i have 5 volts. I checked the fuse link by the starter solenoid and it was fine, but when i checked the same wire at the relay under the seat..........nothing.

side not.................before the sparks, the code reader wasnt running tests. thats why i closed the gaps.

any help would be great

Thanks
James

james51381 · Apr 21, 2004

anyone??

TheUser · Apr 21, 2004

looks like you have a pretty nice setup I'd check the EEC relay. Not sure how you're getting 5 volts at the inertia switch when it doesn't get anything unless the relay sends it and if you're getting nothing at the relay? Maybe you're not testing the correct wires at the fuel pump relay or something. Probably wasn't the best idea to widen the pins, but i've done stupider things...live and learn.

james51381 · Apr 21, 2004

thanks, its an 89 vert so the fuel pump relay is under the seat. So it has to be that relay, right? where is the EEC relay you talking about? Are there anymore fuses i should know about?
james

you have a pretty good setup too.

jrichker · Apr 21, 2004

Fuse link in the wiring harness near the starter relay or solenoid.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

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

james51381 · Apr 21, 2004

jrichker said:
Fuse link in the wiring harness near the starter relay or solenoid.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

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

I was hoping you would chime in................
I read all of your other posts and did all of the test, and still came up empty handed. I will re-check the fuse, but when i took a razor to the plastic protecting it, it looked fine. I think i will just cut it and put an inline fuse.

thanks alot guys
james

james51381 · Apr 21, 2004

I checked again on the fuel relay, and I have 12 volts coming from the starter solenoid, I also put in a new fuel relay. swapped EEC's just to make sure it wasnt the EEC.

how many volts should i be getting between the eec and the fuel pump relay?

james

cjones · Apr 22, 2004

the EEC grounds the relay.

Blue347stang · Apr 22, 2004

I have the same problem with my car. Can't find what the hell is wrong , but I ran a couple of test on my friend's mustang and this is what I found out: Fuel Pump Relay-Ignition "Off": Orange/Lt. wire= 12V, Ignition "On": Red/Black wire=12v, Pink/Black wire(Fuel Pump)=12v, Tan/Lt. green wire= EEC ground. If you check the Pk/Bk wire from the engine compartment on the driver side, you will get .90v,with ignition "on". I'm getting 3v, so I got serious problems with my car .Hope this helps.

jrichker · Apr 22, 2004

The fuse links can open up and still look normal on the outside. Use a voltmeter to measure the voltage drop across them. There should be less than .75 volt drop across a fuse link.

Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground. See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html for a description of the test connector. If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. A tire pressure gauge can also be used if you have one - look for 37-40 PSI. Beware of fire hazard when you do this.

No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – press reset button on the inertia switch. The hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch
B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) Blown fuse link in wiring harness.
F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect for fuel escaping while pump is running.

The electrical circuit for the fuel pump has two paths, a control path and a power path.

The control path consists of the inertia switch, the computer, and the fuel pump relay coil. It turns the fuel pump relay on or off under computer control. The switched power (red wire) from the ECC relay goes to the inertia switch (red/black wire) then from the inertia switch to the relay coil and then from the relay coil to the computer (tan/ Lt green wire). The computer provides the ground path to complete the circuit. This ground causes the relay coil to energize and close the contacts for the power path. Keep in mind that you can have voltage to all the right places, but the computer must provide a ground. If there is no ground, the relay will not close the power contacts.

The power path picks up from a fuse link near the starter relay. Fuse links are like fuses, except they are pieces of wire and are made right into the wiring harness. The feed wire from the fuse link (orange/ light blue wire) goes to the fuel pump relay contacts. When the contacts close because the relay energizes, the power flows through the contacts to the fuel pump (light pink/black wire). The fuel pump has a black wire that supplies the ground to complete the circuit.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

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

Now that you have the theory of how it works, it’s time to go digging.

Look for 12 volts at the Orange/Lt. Blue wire (power source for fuel pump relay). No voltage or low voltage, bad fuse link, bad wiring or connections. There is a mystery connector (one I haven’t found) under the dash somewhere, between the fuel pump relay and the fuse link.

Turn on the key and jumper the fuel pump test connector to ground as previously described. Look for 12 volts at the Light Pink/Black wire (relay controlled power for the fuel pump). No voltage there means that the relay has failed or there is a broken wire in the relay control circuit.
Check the Red/black wire, it should have 12 volts. No 12 volts there, either the inertia switch is open or has no power to it. Check both sides of the inertia switch: there should be power on the Red wire and Red/Black wire. Power on the Red wire and not on the Red/Black wire means the inertia switch is open.

The Tan/Lt Green wire provides a ground path for the relay power. With the test connector jumpered to ground, there should be less than .75 volts. Use a test lamp with one side connected to battery power and the other side to the Tan/Lt Green wire. The test light should glow brightly. No glow and you have a broken wire or bad connection between the test connector and the relay. To test the wiring from the computer, remove the passenger side kick panel and disconnect the computer connector. It has a 10 MM bolt that holds it in place. With the test lamp connected to power, jumper pin 22 to ground and the test lamp should glow. No glow and the wiring between the computer and the fuel pump relay is bad.

If and only if you have followed the test procedure to this point and still haven’t found the problem, the computer is suspect.

Blue347stang · Apr 22, 2004

jrichker said:
There is a mystery connector (one I haven’t found) under the dash somewhere, between the fuel pump relay and the fuse link.

I think the one your talking about is on the driver's side behind the kicker panel. What do you think could be wrong with my car, I'm getting these voltage as followed: Fuel Pump Relay-Ignition "Off": Orange/Lt. wire= 12V, Red/Black wire= 0v, Pink/Black wire(Fuel Pump)= 0v, Tan/Lt. green wire= 0v EEC ground.
Ignition "On": Orange/Lt. blue wire= 12v ,Red/Black wire= 5v, Pink/Black wire(Fuel Pump)= 0v (ground), Tan/Lt. green wire= 5v (EEC ground)

jrichker · Apr 22, 2004

Blue347stang said:
I think the one your talking about is on the driver's side behind the kicker panel. What do you think could be wrong with my car, I'm getting these voltage as followed: Fuel Pump Relay-Ignition "Off": Orange/Lt. wire= 12V, Red/Black wire= 0v, Pink/Black wire(Fuel Pump)= 0v, Tan/Lt. green wire= 0v EEC ground.
Ignition "On": Orange/Lt. blue wire= 12v ,Red/Black wire= 5v, Pink/Black wire(Fuel Pump)= 0v (ground), Tan/Lt. green wire= 5v (EEC ground)

With the ignition switch On, the red/black wire should be 12 volts. Back up to the inertia switch and make sure it has 12 volts on the red/black wire. No +12 volts, check the red wire on the inertia switch. No +12 volts, pull an injector lead off and check the red wire. No +12 volts there, check the ECC relay located on top of the computer for proper operation.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

james51381 · Apr 22, 2004

I am writing from work, so I will have to check this stuff later tonight. It sounds like me and BLUE have the same problem, because I only get 5 volts at the inertia switch on both sides. Thanks alot for the help

james

james51381 · Apr 23, 2004

I checked the red wire and the black wire at the inertia switch. both had 5 volts. I also checked the same wires at the EEC, same thing. I have the constant 12v at the Fuel pump relay and the EEC power relay. nothing on the pink and black, ignition on or off. i am getting really desperate and pissed about this. I dont know what else to check.

The 3 grounds from the comp to the battery were seperated and grounded seperatly, but in the same spot(the firewall where the heads ground) I only have 3 black and green grounds. is that correct?

thanks guys.

james

jrichker · Apr 23, 2004

james51381 said:
I checked the red wire and the black wire at the inertia switch. both had 5 volts. I also checked the same wires at the EEC, same thing. I have the constant 12v at the Fuel pump relay and the EEC power relay. nothing on the pink and black, ignition on or off. i am getting really desperate and pissed about this. I dont know what else to check.

The 3 grounds from the comp to the battery were seperated and grounded seperatly, but in the same spot(the firewall where the heads ground) I only have 3 black and green grounds. is that correct?

thanks guys.

james

You are supposed to have 12 volts at the red/black wire on the inertia switch & the red wire on the fuel pump relay.

No +12 volts and you have a broken wire or bad connection in that circuit. See the diagram from my previous post to clairfy things.

No +12 volts on that part of the circuit (relay coil) and the relay contacts won't close when the computer provides the ground. The fix is to either find the broken wire/bad connection or run a new red wire from pin 37 or 57 (red wire) on the computer to the red wire on the inertia switch.

Measure the voltage across the inertia switch. Put one probe on the red wire and the other on the red/black wire. If it is more than .75 volt, replace the inertia switch.

james51381 · Apr 23, 2004

thanks for the info and patience. I will try that tonight

could it be a bad ground? I did a continuity test from the tan and light green wire from the computer (pin 22) and it wouldnt reach zero, it would stay at 1.3. And both of the red wires to the inertia switch have 5 volts.

thanks for the help
james

cjones · Apr 23, 2004

unplug the inertia switch. what is the voltage at the Red wire?? should be battery voltage with Key ON.

if under 12v check for resistance in that circuit EEC relay to Inertia Switch.

to check for good ground:
Set your volt meter to the 2v scale.
unplug Fuel Pump relay, connect RED voltmeter lead to Self-Test connector Fuel Pump Relay test pin(if you have the connector facing you with the 4 openings on top and the 2 on the bottom it should be the bottom left). connect the NEG lead to the Neg battery terminal. Turn the ignition switch to the RUN position. NOTE: you have 2 seconds to check the reading because that is the circuit that primes the fuel pump. The MAX reading should be no more than 0.05volts. if the reading is higher that that, you most likely have a bad computer ground.

there is 2 computer grounds. 1 by the computer itself and 1 by the battery NEG side with a Black wire going in and a Bk/LG coming out.

james51381 · Apr 23, 2004

cjones said:
unplug the inertia switch. what is the voltage at the Red wire?? should be battery voltage with Key ON.

if under 12v check for resistance in that circuit EEC relay to Inertia Switch.

to check for good ground:
Set your volt meter to the 2v scale.
unplug Fuel Pump relay, connect RED voltmeter lead to Self-Test connector Fuel Pump Relay test pin(if you have the connector facing you with the 4 openings on top and the 2 on the bottom it should be the bottom left). connect the NEG lead to the Neg battery terminal. Turn the ignition switch to the RUN position. NOTE: you have 2 seconds to check the reading because that is the circuit that primes the fuel pump. The MAX reading should be no more than 0.05volts. if the reading is higher that that, you most likely have a bad computer ground.

there is 2 computer grounds. 1 by the computer itself and 1 by the battery NEG side with a Black wire going in and a Bk/LG coming out.

Thanks, the meter showed .04 - .03 I am going to try another red wire from the eec to the inertia switch and see if that helps

james

james51381 · Apr 23, 2004

jrichker said:
You are supposed to have 12 volts at the red/black wire on the inertia switch & the red wire on the fuel pump relay.

No +12 volts and you have a broken wire or bad connection in that circuit. See the diagram from my previous post to clairfy things.

No +12 volts on that part of the circuit (relay coil) and the relay contacts won't close when the computer provides the ground. The fix is to either find the broken wire/bad connection or run a new red wire from pin 37 or 57 (red wire) on the computer to the red wire on the inertia switch.

Measure the voltage across the inertia switch. Put one probe on the red wire and the other on the red/black wire. If it is more than .75 volt, replace the inertia switch.

I checked the inertia switch like you said, and there were no volts between the red wire and the red/black wire, with ignition on or off. I also checked my MAF and INJ, they are also only getting 5 volts (ignition on). I swapped out the power relay for another one and still only 5 volts at the red wire and the orange and light blue wire (they were combined and put into the same slot on the power relay) with ignition on and 0 volts with the ignition off

cjones · Apr 24, 2004

james51381 said:
I checked the inertia switch like you said, and there were no volts between the red wire and the red/black wire, with ignition on or off. I also checked my MAF and INJ, they are also only getting 5 volts (ignition on). I swapped out the power relay for another one and still only 5 volts at the red wire and the orange and light blue wire (they were combined and put into the same slot on the power relay) with ignition on and 0 volts with the ignition off

what is your battery voltage??

what is the voltage, with the EEC power relay removed, on the Bk/O wire at the EEC power relay?? if it's not battery voltage (12v) then disconnect the battery and do an ohms check from Bk/O wire at the EEC power relay to 20 Gauge (Blue) fusible link "G" at the starter relay.

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