PLEASE all Electrical Experts NEED HELP!!!!

[Tony91LX]

OK here is my problem KOEF my fuel pump doesn’t prime,

Checked all the fuseable links at the starter OK
Checked all grounds I could find OK

Replaced Fuel Pump Relay NO Luck
Replaced ECC Power Relay NO Luck
By passed Inertia Relay NO Luck

At the Fuel Pump Relay w/ KOEF
Green w/ Yellow Wire 0V
Pink w/ Black Wire 12.4V
Red 3.63V
Blue w/Orange 0V

If I jump (green/yellow and pink/black fuel pump runs)

At the EEC Power Relay

2 Yellow Wires at one terminal 0V
2 Red Wires at one terminal 4.14V
1 Orange w/ Green 11.6V
Black w/ White 0V

The other thing that weird that could be a major problem it that I can’t scan the codes with a jumper the check engine light never goes out.

[gtsr515]

Check and see if the computer is grounded well behind the pass. kick panel, also there is a small lead off the negative battery cable, is it grounded?

[Tony91LX]

I relocated my battery to the trunk, and grounded the old cable negative cable and wires to the frame. (tests good ground, from the started solenoid to the old negative cable.

I’ll have to check the computer ground, but I never messed around in there, only to change the EEC power relay.

I'll go check it now..

Please keep the the suggestions coming.

Thanks,

Computer Ground checked out ok, PKRWUD any suggestions

[PKRWUD]

When you say KOEF, do you mean KOEO?

My wiring schematic shows different wire colors than the ones you listed.

Try this:
Find the self test connector under the hood. While looking at the connector, hold it so that the line of 4 terminals is below the row of two terminals.

ie:

_ _
_ _ _ _

(except the top two are centered)

Insert a jumper wire between the terminal in the bottom row, farthest right (the wire leading to it should be Tan with a Lt Green tracer), and ground.
Next, turn on the ignition, and listen for the fuel pump.

Does it come on?

Does it stay on?

Take care,
-Chris

[Tony91LX]

Yes KOEO, its been a long day up at 3:30am EST home at 6:00pm

Time for bed I will try it tomorrow, thanks for the reply, I’m hoping you can help me out on this one.

[Tony91LX]

Chris,

I agree with you all the wiring diagrams I have also show different colors and the self test connector is also different.

This is what I have, if we letter the terminals as follows:

A B
C D E F

A has no wire attached
B has a Tan w/ Red
C has no wire attached
D has a Tan w/ Green
E has no wire attached
F has two wires Lt. Blue w/ Orange and Lt Green w/ Orange

Should I go by wire color or terminal position, also just bring the other side of the jumper to any good ground?

Thanks,

[PKRWUD]

What a pain in the arse.

Okay, forget that last part for now.

I've done some research, and it seems like your wiring is more like a '91 F-150 than a Mustang. Anyway, let's start at your first post:

At the Fuel Pump Relay w/ KOEO
Green w/ Yellow Wire 0V
Pink w/ Black Wire 12.4V
Red 3.63V
Blue w/Orange 0V

It should be like this:

At fuel pump relay with the key OFF:
P/B wire = Battery voltage (whatever the voltage is across the battery terminals, ie: 12.4v)
All other wires = Zero volts

At fuel pump relay with the key ON, engine OFF (for two seconds after key is turned on):
P/B wire = Battery voltage
G/Y wire = Battery voltage (zero volts after two seconds)
R wire = Battery voltage
B/O wire = Zero volts

At the EEC Power Relay
2 Yellow Wires at one terminal 0V
2 Red Wires at one terminal 4.14V
1 Orange w/ Green 11.6V
Black w/ White 0V

It should be like this:

At the EEC Power Relay with the key OFF:
Y wires = Battery voltage
All other wires = Zero volts

At the EEC Power Relay with the key ON, engine OFF:
Y wires = Battery voltage
R wires = Battery voltage
O/G wire = Battery voltage
B/W wire = Zero volts

BTW, these readings are all with the specific relay plugged in.

Solution:
One of the Yellow wires at the EEC relay connects to the starter relay's battery post by way of a Blue 20 amp fusible link. The other Yellow wire supplies this power to the ECM. Without constant power to these Yellow wires, the ECM doesn't have proper voltage, and the voltage that allows the Fuel Pump Relay to close never gets to the Fuel Pump Relay. You have a fault in that Yellow wire with the fusible link. It could be a bad fusible link, or a break in the wire.

What you need to do is attach a jumper wire directly from the Battery Post at the Starter Relay to either Yellow wire at the EEC relay. Try it with a long jumper first, and then turn on the ignition. The fuel pump should prime. If it does, try and find where the Yellow wire from the EEC relay to the fusible link fails, and repair it.

Take care,
-Chris

[Tony91LX]

UPDATE IT”S FIXED

One of the first things I looked at when the problem surfaced was the inline fuses, the 20amp fuse for the yellow PCM wire was bent in half so I cut it out and spliced the ends together until I had time to get an inline fuse holder.

$30.00 latter in relays (fuel and EEC Power) and it still wasn’t fixed. While back probing the EEC Power relay and not finding 12V, I went back to that yekkow wire I was getting power just after the splice, but about 6in down the line the wire was damaged, I don’t know how but its fixed.

Thanks, to all those who replied, I hope I can return the favor some day.

I think the EEC power relay was bad anyway when I took it out something was rattling around in side of the relay, I don’t care its fixed. Now it’s going to take a week to put this thing back together.

Once again THANKS

[PKRWUD]

Certainly. It's always kinda cool to hear that I was right on the money without even seeing it in person. Especially when it involves an electrical system that doesn't match any of the "standard" color schemes. Let's me know my brain still works. Sometimes.



Cool.

Take care,
-Chris