Help With Fuel, And Ignition Switch

Discussion in 'Fox 5.0 Mustang Tech' started by louieb, May 11, 2014.

  1. Hi 1986 gt 5.0 coverted to mass air. had intermiten problems, not being able to start car by pressing clutch. i resorted to starting car by shorting sylanoid. now i have a problem it wont start any more. no fuel to system?
    i can hear the fuel pump kick on but i dont think its making it to the fuel rail.

    had the car at service station for 3 weeks, they refused to look at it. so i must fix it myself. it is an older car. but its got so many good poney left

    i need to know if i must first fix the switch, and then check for fuse links, and such. i dont know how to do it, but i need a recomented parts, and tools needed to fix, and dignose.

    so finnaly i have been having problems with the fuel cuting out, before it wont start. still cranks at syinoid,no fuel. also my MSD light is out with key on.

    thanks all..
  2. Fix the ignition switch first that may cure your other problems.

    Recall on Ford Ignition switches:
    Some of the symptoms of ignition switch problems are things that don’t work or are intermittent like radio, turn signals, wipers or heater.

    There was a FREE recall on Ford ignition switches. They overheat and sometimes catch fire. That burns up the steering column and sometimes the car interior. Since this is very old information, you may not be able to get the switch replaced for free anymore. The auto parts stores sell the switches for $13-$15.




    Saleen0679 was nice enough to dig this up for us awhile back: Replace a 1979-1993 Ignition Switch Assembly
  3. ok will do, i have the new switch, but i was told i need a trux key or somthing for 2 safty bolts.

    i guess i will start here after all thank you.

    what do i need to look for at the ignition switch if anything else may be faulty as i replace the switch?
  4. Watch the video, it is very helpful.

    Torx bit set from Advance Auto Parts


    Autocraft torx bit set – have small hole in tip for tamper proof screws.
    Part No. AC571/W1386 Cost approx. $12 +tax

    Diagrams courtesy of Tmoss & Stang&2birds

    Ignition switch wiring

    Fuel, alternator, A/C and ignition wiring

    See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Everyone should bookmark this site.

    Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs

    Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

    Ignition switch wiring

    Fuel, alternator, A/C and ignition wiring

    O2 sensor wiring harness

    Vacuum diagram 89-93 Mustangs

    HVAC vacuum diagram

    TFI module differences & pin out

    Fuse box layout

    87-92 power window wiring PowerWindowWiring.gif

    93 power window wiring

    Visual comparison of the Ford Fuel Injectors, picture by TMoss:
  5. hihi well bad news i changed the switch and now i dont even hear the fuel pump kick on. when i push clutch and turn on key nothing , but have jice at the sylonid to crank.

    my biggest fear its also clutch related, some linkage? or the steering colum is messed up. when i took off switch i could see play between the colum if i put pressure on the wheel.

    but wires looked ok.
  6. How much do you know about automotive electrical systems?
    The 2 diagrams I posted will get you started if you understand how to read them and how automotive electrical systems work.
  7. very little, can you recomend someone in nj, or i might have to sell the car.
  8. I can help, but you may need to request assistance from a friend.

    Automotive circuits are mostly simple stuff: a power source, a connection path, a control device, a load, and a ground.
    The battery/alternator is the positive power source.
    The wire and fuses are the connection path.
    Control devices are switches, relays and sensors.
    A load is a light, motor, solenoid, relay coil or heater element.
    In automotive circuits, grounds are the return path so the electrical power can flow from the load to the negative side of the power source.
    Electricity flows like water:
    Voltage is like pressure,
    Current in amps is like volume,
    Resistance is like the kink you put in a garden hose to decrease the pressure or volume.
    Power is pressure multiplied by volume or voltage multiplied by current (amps)

    Digest that, and you just got the first 3 days of Electricity 101.

    Use some jumper wires (connection path and ground) to hook up a switch (control device), a battery (power source), a light bulb (load). Now make the light turn on and off with the switch.

    That's the electrical lab for the first week of Electricity 101.

    For free automotive electrical training, see Automotive Training and Resource Site . I have personally reviewed the material and it is very good. If you are new to automotive electrical troubleshooting, I highly recommend you spend a hour or so going through the material. You'll save at least that much time troubleshooting problems.

    Using a Multimeter to measure resistance
    Almost every meter has a different method for showing an open circuit. An open circuit is one with a break in it somewhere. That break can be a switch turned off, a fuse blown, a lamp burned out, a bad connector, a damaged circuit board or a cut or burned wire.

    Without reading the instruction manual that came with your meter, I would not try to guess what your readings mean.

    Step 1.) Find the instruction book that came with your Multimeter. Read it and familiarize yourself with how it works and how use it. If you lost the book or didn’t get one with it, do a Google search on the web to find the manufacturer’s web site & download a copy of the manual. Remember that while some meters auto-range to find the correct voltage range, the Ohms function ranges are usually set by the selector switch. Most of the resistance testing done in automotive troubleshooting uses the lowest Ohms range possible.

    Step 2. ) Make sure that you know what test lead plugs into which jacks on the Multimeter. There are usually several different jacks on most Multimeters, and they have different functions. Make sure that your battery(s) in the Multimeter are good: if you have any doubts, replace the battery(s).

    Step 3.) Once you are sure that the Multimeter is functional and you have the leads plugged into the jacks for Ohms ( the Ω symbol), do some simple measurements to make sure that you know how to use it correctly. Set the switch to the lowest range and touch the leads together: you should not see “nothing” but you should see 0.3-1.0 ohms. Measure a 60 watt light bulb: cold it will measure about 17.5 Ohms. It you measure it while it is hot, the reading will be greater.

    Step 4.) Make several test measurements using the ohms function and the DC volts function. Remember all resistance measurements must be done with the power off the circuit. This avoids false readings and possible damage to the ohmmeter.. Repeat steps 3 & 4 until you are sure that you can do it without making any mistakes.

    Step 5.) Then see and carefully study ALL the information under the Heading Chassis Electrical, Basic Electricity – Understanding & Troubleshooting

    Step 6.) Go back and carefully re-read both of my previous posts and download and print the diagrams from the link posted. for wiring diagrams.

    You will need a good volt/ohmmeter with fresh batteries and some simple hand tools.

    Locate the yellow wire on the ignition switch using the diagram I posted. LOOK for loose or damaged wiring or connector pins. Gently tug on the wires to make sure that they aren't loose and not making connection.

    Set the voltmeter to the proper range and DC volts put one wire on the bare metal ground and the other on the yellow wire metal pin for the ignition switch. you should see 12 volts or whatever you have for battery voltage.

    Turn the ignition switch to Run and look for 12 volts on the red/green wire on the ignition switch connector. No 12 volts then the ignition switch isn't working or the red/green wire isn't making a good connection..

    Turn the ignition switch to Start and look for 12 volts on the white/pink wire and red/green wire. No 12 volts, look for damaged wiring , loose connections. since you already replaced the ignition switch, it shouldn't be a problem.

    Turn the ignition switch to Run and look for 12 volts on the red/green wire on the ignition coil. No 12 volts there but good 12 volts at the ignition switch means a blown fuse ink in the ignition wiring. See the second diagram I posted.

    No Crank checklist for 5.0 Mustangs

    Revised 05-Oct-2010 to update Fluke references.

    No crank. slow crank and stuck starter solenoid problems have the same root causes – low battery voltage and poor connections. For that reason, they are grouped together.
    Use the same initial group of tests to find the root cause of both no crank and stuck solenoid problems.

    Since some of the tests will bypass the safety interlocks, make sure that the car is in neutral and the parking brake is set. Becoming a pancake isn’t part of the repair process…

    1.) Will the car start if it is jumped? Then clean battery terminals and check battery for low charge and dead cells. A good battery will measure 12-13 volts at full charge with the ignition switch in the Run position but without the engine running.
    A voltmeter placed across the battery terminals should show a minimum of 9.5-10 volts when the ignition switch is turned to the Start position and the starter engages or tries to engage. Less than this will result in a clicking solenoid, or slow cranking (if it cranks at all) or a starter solenoid that sticks and welds the contacts together.

    Most auto parts stores will check your battery for free. It does not have to be installed in the car to have it checked; you can carry it with you to the auto parts store.

    The battery posts and inside of the battery post terminals should be scraped clean with a knife or battery post cleaner tool. This little trick will fix a surprising number of no start problems.

    The clamp on with 2 bolts battery terminal ends are a know problem causer. Any place you see green on a copper wire is corrosion. Corrosion gets in the clamped joint and works its way up the wire under the insulation. Corroded connections do not conduct electricity well. Avoid them like the plague...

    If the starter solenoid welds the contacts, then the starter will attempt to run anytime there is power in the battery. The cables and solenoid will get very hot, and may even start smoking. The temporary fix for a welded starter solenoid is to disconnect the battery and smack the back of the solenoid housing a sharp blow with a hammer. This may cause the contacts to unstuck and work normally for a while.

    A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection while trying to start the car: more than .5 volts across a connection indicates a problem.

    See for help for help troubleshooting voltage drops across connections and components. .


    2.) Check the battery to engine block ground down near the oil filter, and the ground behind the engine to the firewall. All grounds should be clean and shiny. Use some sandpaper to clean them up.

    3.) Jump the big terminals on the starter solenoid next to the battery with a screwdriver - watch out for the sparks! If the engine cranks, the starter and power wiring is good. The starter relay is also known as a starter solenoid.

    The rest of the tech note only concerns no crank problems. If your problem was a stuck solenoid, go back to step 1.

    4.) Then pull the small push on connector (small red/blue wire) off the starter solenoid (Looks like it is stuck on a screw). Then jump between the screw and the terminal that is connected to the battery. If it cranks, the relay is good and your problem is in the rest of the circuit.

    5.) Remember to check the ignition switch, neutral safety switch on auto trans and the clutch safety switch on manual trans cars. If they are good, then you have wiring problems.

    Typical start circuit...
    Diagram courtesy of Tmoss & Stang&2birds

    6.) Pull the starter and take it to AutoZone or Pep Boys and have them test it. Starter fails test, then replace it. If you got this far, the starter is probably bad.

    Starter solenoid wiring for 86-91 Mustang

    Starter solenoid wiring 92-93 Mustang or earlier Mustang with upgraded high torque mini starter.

    Electrical checks for the switches and starter solenoid

    Remove the small red/blue wire from the starter solenoid. Use a screwdriver to bridge the connection from the battery positive connection on the starter solenoid to the small screw where the red/blue wire was connected. The starter should crank the engine. If it does not, the starter solenoid is defective.

    If the starter does crank the engine, the problem is in the clutch safety circuit (5 speed) or Neutral Sense Switch (auto trans) or ignition switch.

    Typical start circuit...
    Diagram courtesy of Tmoss & Stang&2birds

    You will need a voltmeter or test lamp for the rest of the checks. Connect one lead of the voltmeter or test lamp to ground. The other lead will connect to the item under test.
    Look for 12 volts on the white/pink wire when the ignition switch is turned to the Start position. Check the ignition switch first.
    No 12 volts, replace the ignition switch.

    The next step will require you to push the clutch pedal to the floor (5 speed) or put the transmission in neutral (auto trans) while the ignition switch is turned to the Start position.
    Good 12 volts, check the clutch safety switch (5 speed) or Neutral Sense Switch (auto trans) for good 12 volts on both sides of the switches. No 12 volts on both sides of the switch and the switches are defective or out of adjustment. Check the wiring for bad connections while you are at it.