Electrical Crank no start... Getting closer but need some help!?

saywoodj

Member
Jun 28, 2022
7
4
13
23
New England
Firstly, I'm very thankful for the great information on this site with regard to troubleshooting this crank no start topic :).
I've done a bunch of testing, and don't know the next steps... and was hoping someone more intelligent could assist!

See attached photo showing the results of the volt meter testing. And to qualify, I'm novice for sure...
IMG_1379.jpg
With the fuel pump test port jumped (tan/green) and the inertia jumped, I get power to the fuel pump. (Fuel pump is good and ground)

Without fuel pump test port jumped I have not power to the red/black or pink/black but I do get a click at the fuel pump relay? I got a relay from NAPA to check and they assured me it was compatible but...

I'm thinking I may need to test the tan/green wire from the EEC 22 but not sure how or if that would help? Could it be a computer issue?

I'm missing something but need some help form here if you can!?

Thank you for the help!
 

rednotch

Founding Member
Aug 14, 2000
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136
63
south jersey
www.cardomain.com
Will the car start with the test port grounded and the pump running? Do you see a check engine light when you key the car on? Can you pull any codes ? If not, I would suspect the ecu and pin 22 not grounding that circuit. If yes I would continue probing the wiring. Ecu exchange on eBay does good, quick and reasonably priced repairs, he owns an SSP car if I remember right, rebuild runs about 130 shipped threw him, and he can replace more the just the capacitors that most do. Better then trying to located a good used 30 year old ecu for double or triple the cost or dealing with parts house selling cardone and blue streak remans that are hard to get.
 
I spent 2 weeks troubleshooting a crank no start issue as well. Finally got to the eec relay step and replaced it. It started. Few days later, no start again except this time no fuel pump prime. Sent my ECU to ECU Exchange for rebuild. I haven’t had any issues since.
 
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saywoodj

Member
Jun 28, 2022
7
4
13
23
New England
Thanks everyone for the replies.

One more thing to mention (sorry)!

at the inertia switch... I have power at the red wire, but no power to the red black. with the inertia jumped, I still do not have power to the red/black at the fuel pump relay?

I ran a dummy test wire from the jumped inertia switch red/black to the red/black at the fp relay to supply power. Doing this and with the test port jumped I had power at the fuel pump. No power without the test port jumpered.

Also, for some background.... this seemed to have happened after I had replaced the fuel sending unit.

I'm definitely interested in getting some more information on having the computer checked/updated as well.

Not sure if this will help narrow down the issue or add more to it?!
Thanks again!
 

saywoodj

Member
Jun 28, 2022
7
4
13
23
New England
No, the fuel pump does not get power when the inertia switch is plugged in and the test port is jumped.

Only power at the fuel pump I can get is when the test port is jumpered and I run a wire from the jumped inertia switch red/black to the fp relay red/black.

Thanks for the reply!!
 

saywoodj

Member
Jun 28, 2022
7
4
13
23
New England
Thank you. I've copied step #4 with status below:

4.) No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – Coupe & 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
-No power to the red/black at switch
- I jumped the inertia switch to eliminate

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. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
-No power to pink/black on fp relay
C.) Clogged fuel filter
-New fuel filter (but no power to fuel pump so we can eliminate at this point)
D.) Failed fuel pump
-tested fuel pump with bench battery - all good
E.) 86-90 models only: Blown fuse link in wiring harness. Look for 12 volts at the Orange/Lt Blue wire on the fuel pump relay.
-1988 car & has power to the orange/blue wire at fp relay
91-93 models only Blown fuse link in wiring harness. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
The fuse links for all model years 86-93 live in the wiring harness near the starter solenoid.
1988 car would this one not apply for 91-93 only does this not apply? Or does this point to fuse link for pink/black??

Thank you!!
 

rednotch

Founding Member
Aug 14, 2000
367
136
63
south jersey
www.cardomain.com
With these cars getting to be 30+ years old I would send in the computer to be checked and updated as part of the normal 'tuneup and repair' procedure, I have two computers at the exchange now.
Fuse links are getting nasty too with age, bought a couple 10ft rolls in factory sizes and have been replacing them on mine, hard to color match them these days though, . Couple of cars ive owned or worked on had low voltage issues from corrosion in the factory joints where it steps down in size to the fuse link in the wiring harness.
 

saywoodj

Member
Jun 28, 2022
7
4
13
23
New England
Thank you. I pulled up the fuse link wiring diagram and inspected the fuse links and they look fine, nothing to note visually/touch.
IMG_1385.jpg
Following the wiring paths and voltages, should the the fuse links be good?
DARK BLUE Wire Fuse Link - I have power to the EEC relay black/orange, Ignition coil, ignition switch, etc.
YELLOW Wire Fuse Link - I have 12v at orange/lt blue wire at fuel pump relay.

IMG_1387.jpg

I have power at the red wire at the inertia switch
I have power at the orang/lt blue at fp relay

but am not making a circuit for the red/black and tan/lt green wiring path between the EEC and inertia switch.

I also don't understand why when I jumper the inertia switch I don't get power on red/black at the fuel pump relay?

Again, thank you very much for the help. super novice but trying to make my way through this... not many shops interested in tackling this right now.