1987 5.0 NEED HELP

I have an issue starting the car with the key the previous owner had put a push start button with the wire leading to the starter solenoid and recently that had stopped working as well I’ve checked the ignition switch located under the steering wheel and it looks like it’s still on there pretty good and I also have an issue with the fuel pressure being < 10psi with the relay constantly clicking and the fuel pump staying on after I turn the key and never shutting off and thus I looked at the inertia switch in the trunk and I didn’t have any current on either side of the switch so maybe that’s the issue? I hope these pictures help and if you have any questions please ask! Thanks stang community!
 

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AeroCoupe

Founding Member
Oct 28, 2001
547
235
73
Jenks, OK
First you need to ditch the push button start and get the car starting back on the key switch. From there you need to look at the fuel pump relay under the driver seat and see if you have power to it and when you put the key in the run position is there power on the fuel pump side of the relay. If there is power but no power when priming the fuel pump check and see if the EEC is putting power to the relay to close the contact. If the EEC is doing its job and you have no power to the relay then that is either the problem or one of the problems. If the EEC is not doing its job then you need to start working back towards the EEC and see what is going on there (bad EEC power relay, bad EEC, bad grounds, etc.).

Really once you get the car cranking off the key switch I would go to this tech article and work the problem.

 
First you need to ditch the push button start and get the car starting back on the key switch. From there you need to look at the fuel pump relay under the driver seat and see if you have power to it and when you put the key in the run position is there power on the fuel pump side of the relay. If there is power but no power when priming the fuel pump check and see if the EEC is putting power to the relay to close the contact. If the EEC is doing its job and you have no power to the relay then that is either the problem or one of the problems. If the EEC is not doing its job then you need to start working back towards the EEC and see what is going on there (bad EEC power relay, bad EEC, bad grounds, etc.).

Really once you get the car cranking off the key switch I would go to this tech article and work the problem.

Thanks for the reply! How would I go about switching the button back to the key switch? Is there a wire in the ignition switch that is tapped?
 

AeroCoupe

Founding Member
Oct 28, 2001
547
235
73
Jenks, OK
You need a wiring diagram for the car. I would start another thread and see if someone has one they would share with you. The reason I say this is I am not there looking at the car and do not have a wiring diagram. I do know that on the starter solenoid there is a red / blue wire (the one that the yellow wire is connected to) originates at the ignition switch as a white / pink wire, goes through the neutral safety switch, then through the clutch switch, and on to the TFI module and over to the starter solenoid on the inner fender.


You need to make this circuit work and the car will crank over. Once you have this done then go to work on the crank but will not start check list.
 

CAMTWO1070

Active Member
Dec 17, 2021
163
48
38
NY
From what I see your wiring at the starter solenoid needs alot of help......Your ground wires and the wire coming from the battery feeding the starter solenoid too...

You need to take alot of those stacked up wires and distribute them better using a heavy duty battery terminal or a dual terminal battery and put a new battery cable aswell as remove the grounding wires on the uni-body and clean them up with a wirewheel or sandpaper then after reinstallation protected with battery terminal protection spray.........

I have a starter from a 90 Lincoln towncar that has a solenoid built-in so I use both terminals of the stock starter solenoid as a power distribution point.....

Screenshot 2021-12-06 215318.png


Having one of these dual terminal batteries helps out alot to distribute power and grounds plus the dual terminal batteries also come in the cheaper brands too..I run my MSD 6A box on the seperate terminals and I also use a 120,000mfd in-line capacitor to keep the MSD properly fed......
IMG_20201109_123712358.jpg

IMG_20220620_165558.jpg

IMG_20221112_175848_0CS.jpg


Post up some pics of how your fuelpump relay is mounted and how its wired because some buy a replacement plug and rewire the relay like the EEC relay plug and thats not correct...Theres two main pins coming from the ECU that controls and senses the fuelpump and thats Pin #22 and pin #19

Pin #22 is a ground and the ECU triggers the fuelpump and turns it off after the 2 second prime using the green wire on pin #22...

88-91_5.0_EEC_Wiring_Diagram1.gif


I guarantee once you redo your power cables and clean up those very aweful and dirty grounds going to the unibody which are very important ECU ground wires and also one is a ground wire for the EEC relay plus you should also replace your EEC and Fuelpump relays with ones with protective diodes plus maybe replace your fuelpump relay plug too and your troubles will get better if not be totally resolved if the ECU isnt old and compromised....

EEC IV Grounding method.png


Screenshot 2022-10-25 190227.jpg


Oh and this is the wire you need to make the keyswitch work again...................I circled it and used your picture

C80553F2-B5FE-4067-A5EE-3250162980C1.jpeg

It might work out better to run the new wire for the starter from the pushbutton to the terminal on the ignition switch marked start ..

th (2).jpg


Good Luck
 
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