Fuel pump won't turn on...

[jrichker]

Just to note.
This is not the same resister Im speaking of but then again this copy & pasted info is listed as "O2 sensor harness warnings".
Not sure if the OPs car has the correct wiring so who knows what caused his EEC issue except for maybe VertVert LoL.
VertVert, the circult pictured above, do you know if its inline to the fuel relay also??
I know the 1 Im speaking does.
My understanding is there is several EEC grounds that go to different external components.

VertVert: The computers in our 5.0 Mustangs are all multilayer through hole PCB construction. if I remember correctly, there aren't any surface mount components in the PCB. Email me and I'll send you an A9L diagram and some information on the computer details.

To All: Perhaps my computer interchange note could have been better worded or arranged...

fordjunky: Two EEC grounds are present: the main power ground is on computer pins 40 & 60. The power ground starts out as 2 wires and terminates as 1 wire near the starter solenoid. It connects to the ground pigtail on the battery ground wire using a quick disconnect coupler. Due to its proximity to the battery, the quick disconnect coupler may become corroded by acid fumes from the battery.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness.

The computer case ground on computer pin 20 and grounds to the floor pan near the computer..

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 Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

 

[fordjunky]

VertVert: The computers in our 5.0 Mustangs are all multilayer through hole PCB construction. if I remember correctly, there aren't any surface mount components in the PCB. Email me and I'll send you an A9L diagram and some information on the computer details.


fordjunky: Two EEC grounds are present: the main power ground is on computer pins 40 & 60. The power ground starts out as 2 wires and terminates as 1 wire near the starter solenoid. It connects to the ground pigtail on the battery ground wire using a quick disconnect coupler. Due to its proximity to the battery, the quick disconnect coupler may become corroded by acid fumes from the battery.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness.

The computer case ground on computer pin 20 and grounds to the floor pan near the computer..

I understand this info you list as where the EEC gets its ground "from" but Im speaking as the grounds the EEC "sends out to actuate components".

The fuel relay is activated by a ground signal from the EEC pin 22.
Pin 22 ties the under hood test port & EEC & fuel relay together.
So if the resister I speak of is bad then there will be no "sends out to actuate components" signal to the fuel relay.


As surface mount components goes, thats were the resisters & capacitors are mounted & not between the layers of PCBs.

 

[biminiblue92]

Thanks for the detailed information. Being a noob, much of that is way over my head right now, and probably will be forever, which is why I am grateful for all your help and time.

With the car functioning fine once I jump out the EEC and the relay clicking, I'm down to the possible causes of the inline fuse to the relay OR I need to find somewhere a refurb EEC?

With the car being 20 years old now, if it's the EEC, I'd rather go with the refurb for some peace of mind. Haven't yet found a source for refurbs, but I will keep looking.

 

[fordjunky]

The fuel relay has constant positive power off the starter silynoid (fusable link).
You gave the fuel relay the "EEC sends out a ground to actuate components" signal when you bypassed the the EECs signal when YOU grounded the relay.
The fusable link is fine.
Azone has them on there site

 

[jrichker]

I understand this info you list as where the EEC gets its ground "from" but Im speaking as the grounds the EEC "sends out to actuate components".

As surface mount components goes, thats were the resisters & capacitors are mounted & not between the layers of PCBs.

Just for the record, I have a 2 year degree in electronics and have been fixing computers large and small for over 32 years. I have fixed more PCB's than I can ever remember. I am very aware of how and where the components in a multilayer construction PCB are mounted.

The technology used to refer to the computer providing grounds for the actuators is called current sink technology. It reduces the number of computer failures by not providing power to a load, but providing a ground for it. If you were familiar with 7400 TTL series IC logic, it would be very natural to you.
See Interfacing to Digital Inputs and Outputs for more information.

 

[biminiblue92]

I guess it's best if I pull the EEC out and look at the part number, but whats the difference between:

A9P - 89-93 5.0L Mustang Auto Mass Air
and
C3W - 89-93 5.0L Mustang Auto

I thought all Mustangs from 1989 were Mass Air (I have an auto)?

 

[fordjunky]

Just for the record, I have a 2 year degree in electronics and have been fixing computers large and small for over 32 years. I have fixed more PCB's than I can ever remember. I am very aware of how and where the components in a multilayer construction PCB are mounted.

The technology used to refer to the computer providing grounds for the actuators is called current sink technology. It reduces the number of computer failures by not providing power to a load, but providing a ground for it. If you were familiar with 7400 TTL series IC logic, it would be very natural to you.
See Interfacing to Digital Inputs and Outputs for more information.

That's nice.
Im not questioning your training & experience but you "quoted" (copy & pasted) to ME something vertvert posted as reference so I responded to that reference YOU posted.

As current sink technology, your post 21 did not speak of this, you only spoke of where the EEC gets its ground from & that's what I responded to.

 

[jrichker]

Spitting contest ended. I will politely let you carry on without any further remarks.

 

[fordjunky]

Spitting contest ended. I will politely let you carry on without any further remarks.

Come on man, I STILL LOVE YOU.

 

[fordjunky]

I guess it's best if I pull the EEC out and look at the part number, but whats the difference between:

A9P - 89-93 5.0L Mustang Auto Mass Air
and
C3W - 89-93 5.0L Mustang Auto

I thought all Mustangs from 1989 were Mass Air (I have an auto)?

C3W is the updated A9P if I remember correct but Im looking the website that has that info (I forgot the name LoL)
I was going to send you a pm (to direct links of EECs as to not posting 4sale items in the tech section as per forum rules) but you must have it selected off.

That site that I spoke of was shut down do to legal issues of fordfuelinjection.com & NOW is back as www.oldfuelinjection.com

 

[biminiblue92]

I need an A9P. Would like to get a refurb, not used.

Checked locally, and they (Autozone and Pep Boys) no longer do them. Any suggestions?
Ford?

 

[fordjunky]

I PM-ed you a coupe links.

 

[biminiblue92]

I PM-ed you a coupe links.

Ok. So I got an refurbished EEC, and unfortunately, it made matters much worse.

The fuel pump still wouldn't turn on with the new EEC, the car started once but stalled right after and never started again. Couldn't get the pump to turn on via jumping the EEC.

Switched back to the old, and had similar problems but I was able to jump the EEC and get running, but only once.

Eventually, the fuel pump wouldnt run at all, no matter what. The car eventually took more effort to even turn over, and eventually stopped turning over.

Worse still, I hooked up a battery charger to charge up my battery, which is fairly new, and the charger essentially went on fire, with the insulation melting on the cables.

EEC clicks, when I turn on the ignition, but now nothing. Any suggestions before I have this towed in to a shop.

Can t imagine how or why things went so wrong with this.

 

[fordjunky]

Ok. So I got an refurbished EEC, and unfortunately, it made matters much worse.

The car did start BUT something else has arisen.

The fuel pump still wouldn't turn on with the new EEC, the car started once but stalled right after and never started again. Couldn't get the pump to turn on via jumping the EEC.

It "started once" says that either the fuel pump did come on or there was still pressure built up in the fuel lines.
If the fuel pump didn't come on then sounds like maybe a bad EEC.
If the pump did come on & its not working now points to other issues has arisen.

Switched back to the old, and had similar problems but I was able to jump the EEC and get running, but only once.

You got it running says the power to the fuel system is fine but then lost it so something else has arisen.

Eventually, the fuel pump wouldn't run at all, no matter what. The car eventually took more effort to even turn over, and eventually stopped turning over.

Possibly flooding. Sparkplugs likely will be wet with gas.
Possible the starter is going out or it got hot from excessive cranking.
I'm doubting the engine is seizing.

Worse still, I hooked up a battery charger to charge up my battery, which is fairly new, and the charger essentially went on fire, with the insulation melting on the cables.

Cant see this being car related.
Maybe it set at max to try to start a flooded engine.

EEC clicks, when I turn on the ignition, but now nothing. Any suggestions before I have this towed in to a shop.

Sounds like the 20g fusable link may have blowed that's mounted on the deadman/starter solenoid that feeds the EEC relay mounted above the EEC.

Can t imagine how or why things went so wrong with this.

Frustration influences concentration.

Power for the fuel pump comes through a fusible link on the deadman/starter solenoid , to the fuel pump relay, to the resettable switch in the trunk, to the fuel pump.
Once you get this area addressed then you should be able to start the car "again" by grounding the 22 wire if the EEC happens to be bad again.


I would check the fusible links on the deadman/starter solenoid 1st.
This 1 is by itself
20g EEC, BK/Orange

These are grouped together.
18g fuel pump, Orange/Lt blue
16g fuse box, BK/Orange
18g key switch assembly, Yellow



Also note when you do a test by bypassing this ground signal to start the car make sure you give it a good ground contact. (Not 1 that makes the pump turn on & off "spikes" because it can blow a resister in the EEC).

 

[biminiblue92]

OK. Thanks for keeping my focused and lending me some more of your time.

Tried cranking again today, but would't turn over. Very sluggish crank. Similar to trying to crank with a battery thats about to die.

Put a reader on it. Among the codes, I got a 96 with key in ignition but ignition not on. 96 is fuel pump secondary circuit fault/high speed fuel pump relay open.

In dummy terms, what does this mean. Also codes 21, 24, 81, 82, and 30.

Thx again. Tomorrow is another day...

 

[jrichker]

Code 96 causes & tests 91-93 models. – KOEO- Fuel pump monitor circuit shows no power - Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits. The fuel pump circuit lost power at one time or another.

Look for a failing fuel pump relay, bad connections or broken wiring. The fuel pump relay is located under the Mass Air Meter on Fox bodied stangs built after 91. On earlier model cars is under the passenger seat. On Mass Air Conversions, the signal lead that tells the computer that the fuel pump has power may not have been wired correctly. See Mustang Mass Air Conversion | StangNet

Diagram of the fuel pump wiring for 91-93 cars.

Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when the test connector is jumpered to the test position. To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground. No voltage when jumpered, check the fuel pump relay and fuse links.

Power feed: Look for 12 volts at the pink/black wire (power source for fuel pump relay). No voltage or low voltage, bad fuse link, bad wiring, or connections. Remember that on 92 or later models the fuel pump relay is located under the Mass Air meter. Watch out for the WOT A/C control relay on these cars, as it is located in the same place and can easily be mistaken for the fuel pump relay.

Relay: Turn on the key and jumper the ECC test connector as previously described. Look for 12 volts at the dark green\yellow 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.

91-93 Models:
Using the diagram, check the dark green/yellow wire from the fuel pump relay: you should see 12 volts or so. If not the relay has failed or is intermittent. Check the inertia switch: on a hatch it is on the drivers side by the taillight. Look for a black rubber plug that pops out: if you don't find it, then loosen up the plastic trim. Check for voltage on both sides of the switch. If there is voltage on both sides, then check the Pink/black wire on the fuel pump relay: it is the power feed to the fuel pump. Good voltage there, then the fuel pump is the likely culprit since it is getting power. No voltage there, check the Pink/black wire, it is the power feed to the fuel pump relay & has a fuse link in it. Good voltage there & at the dark green/yellow wire, swap the relay.

Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor.
Note that that if the outside air temp is below 50 degrees F that the test for the ECT can be in error. Warm the engine up until you get good hot air from the heater and then dump the codes again.

The ECT sensor has absolutely nothing to do with the temperature gauge. They are different animals. The ECT sensor is normally located it the passenger side front of the engine in the water feed tubes for the heater.

The ACT & ECT have the same thermistor, so the table values are the same

ACT & ECT test data:

Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Voltages may be measured across the ECT/ACT by probing the connector from the rear. A pair of safety pins may be helpful in doing this. Use care in doing it so that you don't damage the wiring or connector.

Here's the table :

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.

50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms

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 http://www.veryuseful.com/mustang/tech/engine/

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

b]Code 24[/b] - Intake Air Temperature (ACT) sensor out of range.
Bad sensor, bad wiring. The ACT for Mustangs built before 95 is in the
#5 intake runner. It measures the air temperature in the intake to help
computer the proper air/fuel ratio.

Note that that if the outside air temp is below 50 degrees F that the test for the ACT can be in error.

ACT & ECT test data:

The ACT & ECT have the same thermistor, so the table values are the same

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts.
It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in
the lower intake manifold, the voltage readings will be lower because of the heat transfer.
Here's the table :

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected,
or at the sensor with the sensor disconnected.

50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms


Code 81 – Secondary Air Injection Diverter Solenoid failure AM2. The solenoid valve located on the back side of the passenger side wheel well is not functional. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Lt Green/Black wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the LT Green/Black wire for the solenoid valve.

With the with the ignition on, look for 12 volts on the red wire on the solenoid connector. No 12 volts and you have wiring problems.

With the engine running, stick a safety pin in the LT Green/Black wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the cats. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Putting the computer into self test mode will cause the solenoid valve to toggle. If you listen carefully, you may hear it change states.


Code 82 – Secondary Air Injection Diverter Solenoid failure AM1. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Red/White wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the Red/White wire for the solenoid valve

With the engine running, stick a safety pin in the Red/White wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the heads. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Both 81 & 82 codes usually mean that some uneducated person removed the solenoid control valves for the Thermactor Air system in an attempt to make the car faster. It doesn't work that way: no working control valves can cause the cat converters to choke and clog.

Sorry, I don't have code definition for code 30, and it isn't in The Probst book which is the reference guide for 5.0 Mustangs.

 

[biminiblue92]

30 has something to do with cylinder balance.

I started taking a look at some of the troubleshooting.

Of note, when I was jumping the EEC, I was able trick the fuel pump on just briefly one more time, but I wasn't able to replicate.

Moving to the relay itself.

With the key on and the jumper in, at the relay, I have like 8.7 volts on the pink/black (which is the feed). I have like .5 on the dark green/yellow (which is the power from the relay to the pump).

Relay failing or working intermittently?

I took the relay from the WOT, which I have heard was the same (and then I also heard that it wasn't), and placed it in the fuel pump relay and there was no change.

If I have power to that relay, that fuseable link is good, right?

Getting really cold here in NY, so I'm not sure if my battery is starting to need a boost, which may make this more complicated for me.

More importantly....I think I can only count on my wife pushing this puppy out of the garage one or two more times for me to work on it , but I'll get it done.

 

[jrichker]

All testing is done with the ignition switch in the Run position. Do not forget this crucial step.

The pink/black wire s should have the same voltage as the battery positive terminal +/- 0.25 volt. If not, then the fuse link for the fuel pump has opened up.

With the test jumper in place the green/yellow wire should be the same voltage as the pink/black wire +/- 0.25 volt.

If not, look at the red wire: should have the same voltage as the battery positive terminal +/- 0.25 volt.
If not, then check the yellow wire on the EEC relay located on top of the computer. This one is hard to get to. It should have the same voltage as the battery positive terminal +/- 0.25 volt. If not, then the fuse link for the computer has opened up.

If the red wire does not have the same voltage as the battery positive terminal +/- 0.25 volt and the yellow wire on the EEC relay does, then check the red/green wire on the EEC relay. It should have the same voltage as the battery positive terminal +/- 0.25 volt. If not, then the ignition switch is defective or the fuse link in the ignition wiring harness has opened up, or the EEC relay is defective.

Diagram courtesy of Tmoss & Stang&2birds

 

[biminiblue92]

Ok. Trying to keep my head up, but I think I'm starting to think that I'm not going to be able to repair this myself.

I continued with the diagnostics, and here's what I got this morning.

Battery (key off) 11.38
Battery (key run) 10.38
Battery (key on w/jumper) 9.7

pink/black (w/jumper 7.55 to 7.68)

Battery (key run no jumper) 7.64
pink/black (key run no jumper) 7.60

green/yellow (key run w/jumper) 5.35
pink/black (key run w/jumper) 5.19

I left the car in run with jumper on for most of my troubleshooting, which I probably shouldn't have done in hindsight to conserve some power.

So I have my original EEC, and a tested refurbished one, and I'm also faced with a time crunch now bc if the issue wasn't the EEC, then I have to return the refurbished one soon.

I'm frustrated that I was able to jump EEC test and start and run the car no problem before, but as soon as I swapped the EEC, I wasn't able to essentially do anything anymore, and now the car won't even crank for me. Just venting.

 

[jrichker]

Rob your piggy bank for a battery charger: hook it up and let it charge at least overnight. Low voltage is going to complicate your troubleshooting process. The computer and most of the other electrical stuff doesn’t work well once the voltage drops below 10 volts.