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1987 5.0 NEED HELP

  • Thread starter Thread starter Foxbody.Jay
  • Start date Start date Nov 16, 2022
F

Foxbody.Jay

New Member
Nov 16, 2022
2
0
1
7215 Silver Meadow Ct
Nov 16, 2022
#1
  • Nov 16, 2022
  • #1
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

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,796
3,928
183
Claremore, OK
Nov 16, 2022
#2
  • Nov 16, 2022
  • #2
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.

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995 A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work...
www.stangnet.com
 
F

Foxbody.Jay

New Member
Nov 16, 2022
2
0
1
7215 Silver Meadow Ct
Nov 16, 2022
#3
  • Nov 16, 2022
  • #3
AeroCoupe said:
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.

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995 A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work...
www.stangnet.com
Click to expand...
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

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,796
3,928
183
Claremore, OK
Nov 16, 2022
#4
  • Nov 16, 2022
  • #4
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.

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

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.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,176
17,878
224
Massachusetts
Nov 16, 2022
#5
  • Nov 16, 2022
  • #5
Here’s the 1988 factory EVTM. It’s about 99% identical to 1987 and should cover you.

1988 Mustang Electrical & Vacuum Troubleshooting Guide (EVTM)

File is too large to upload. Here is link to it on my Google Drive. View: https://drive.google.com/open?id=1on5czXKmpETzxUggWTGtoUuVkJT2UUxN
www.stangnet.com
 

CAMTWO1070

Active Member
Dec 17, 2021
232
76
38
NY
Nov 18, 2022
#6
  • Nov 18, 2022
  • #6
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.....



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......




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...



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....





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


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 ..



Good Luck
 
Last edited: Nov 19, 2022
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