Wont Start Sometimes.

Discussion in '1994 - 1995 Specific Tech' started by 94coupe, Mar 6, 2014.


  1. 94coupe

    94coupe Member

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    not only will it not star sometimes.....I cant pull any codes. I can hear things cycling when I presss test, but reader just reads zeros.? now if I cycle the key a few times it starts right up. I just replaced the fuel pump, neew distributor wires and plugs. im thinking computer?
    thanks caam.
    #1
  2. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    `` 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 your way down. Jumping around will possibly cause you to miss just what you need to see to find and fix the problem. Don’t skip any steps because the next step depends on the last step working correctly.


    Revised 12-Dec-2011 to replace 10 pin salt & pepper connector graphic.

    All text applies to all models unless stated otherwise.

    Note: 94-95 specific changes are in red

    1.) Remove push on connector (small red/blue wire) from starter solenoid and turn ignition switch to the Run position. Place car in neutral or Park and set the parking brake. Remove the coil wire from distributor & and hold it 3/8” away from the engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
    Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.

    No spark, possible failed items in order of their probability:
    A.) MSD or Crane ignition box if so equipped
    B.) PIP sensor in distributor. The PIP sensor supplies the timing pulse to trigger the TFI and injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed. See paragraph 5A – Using a noid light will tell if the PIP is working by flashing when the engine is cranking.
    C.) TFI module: use a test light to check the TFI module. Place one lead of the test light on the red/green wire on the ignition coil connector and the other lead on the dark green/yellow wire on the ignition coil connector. If the TFI is working properly, the test light will flash when the engine is cranked using the ignition switch.
    D.) Coil
    E.) No EEC or computer power - EEC or computer relay failure
    86-93 models only: EEC relay next to computer - look for 12 volts at the fuel injector red wires.
    94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
    Both 86-93 and 94-95 models: No 12 volts with the ignition switch in the run position on the fuel injector red wires. The relay has failed or there is no power coming from the ignition switch. Make sure that there is 12 volts on the red/green wire on the coil before replacing the relay.
    F.) No EEC or computer power - fuse or fuse link failure
    86-93 models only: Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid. Look for a 20 gauge blue fuse link connected to 2 black/orange 14 gauge wires.
    94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
    G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire. No 12 volts, blown fuse link or faulty ignition switch. Remove the plastic from around the ignition switch and look for 12 volts on the red/green wire on the ignition switch with it in the Run position. No 12 volts and the ignition switch is faulty. If 12 volts is present in the Run position at the ignition switch but not at the coil, then the fuse or fuse link is blown.
    Note: fuses or fuse links blow for a reason. Don’t replace either a fuse or fuse link with one with a larger rating than stock. Doing so invites an electrical fire.
    Ignition fuse links may be replaced with an inline fuse holder and 5 amp fuse for troubleshooting purposes.
    94-95 models only: Check inside fuse panel for fuse #18 blown – 20 amp fuse
    H.) Missing or loose computer power ground. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery.
    In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
    In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
    You'll find it up next to the starter solenoid where the wire goes into the wiring harness
    I.) Computer. Don’t replace the computer just because you don’t understand how it works. Computers seldom fail, it usually is a sensor or wiring problem that causes the problems.
    J.) Bad or missing secondary power ground. It is located between the back of the intake manifold and the driver's side firewall. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges.
    K.) Engine fires briefly, but dies immediately when the key is released to the Run position. Crank the engine & when it fires off, pull the small push on connector (red/blue wire) off the starter relay (Looks like it is stuck on a screw). Hold the switch in the crank position: if it continues to run there is a problem with either the ignition switch or TFI module. Check for 12 volts at the red/green wire on the coil with the switch in the Run position. Good 12 volts, then replace the TFI. No 12 volts, replace the ignition switch.

    Wiring Diagrams:

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

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

    Fuel, alternator, A/C and ignition wiring
    http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

    Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

    Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

    Complete computer, actuator & sensor wiring diagram for 94-95 Mass Air Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/94-95_5.0_EEC_Wiring_Diagram.gif


    AutoZone wiring diagrams: You can navigate to the diagrams yourself via Repair Info | AutoZone.com and select the car year, make, model and engine. That will enable you to bring up the wiring diagram for your particular car.

    2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability: [/b]
    A.) Moisture inside distributor – remove cap, dry off & spray with WD40
    B.) Distributor cap
    C.) Rotor
    D.) Spark Plug wires
    E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil

    3.) Spark at spark plug, but no start.
    Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air duct off at the throttle body elbow, open the throttle, and spray the ether in it. Reconnect the air duct and try to start the car. Do not try to start the car without reconnecting the air duct.

    Two reasons:
    1.) If it backfires, the chance for a serious fire is increased.
    2.) On Mass Air cars, the computer needs to measure the MAF flow once the engine starts.
    If it starts then, you have a fuel management issue. Continue the checklist with emphasis of fuel related items that follow. If it doesn’t, then it is a computer or timing issue: see Step 4.

    Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 2-4 seconds and shut off. To trick the fuel pump into running, find the EEC test connector and jump the connector in the Upper RH corner to ground. The EEC connector is near the wiper motor and LH hood hinge.

    [​IMG]

    If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the Schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. Beware of fire hazard when you do this. In a pinch, you can use a tire pressure gauge to measure the fuel pressure. It may not be completely accurate, but you will have some clue as to how much pressure you have. If you have any doubts about having sufficient fuel flow/pressure, rent a fuel pressure test gauge from the auto parts store. That will tell you for sure if you have adequate fuel pressure.


    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
    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.
    C.) Clogged fuel filter
    D.) Failed fuel pump
    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.
    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.
    94-95 models only: 20 amp fuel pump fuse in the engine compartment fuse box. Look for 12 volts at the Dark green/yellow wire on the constant control relay module.
    F.) Engine seem to load up on fuel and may have black smoke at the tailpipe. Fuel pressure regulator failed. Remove the vacuum line from the regulator and inspect for fuel escaping while the pump is running. If fuel is coming out the vacuum port, the regulator has failed. Check the regulator vacuum line for fuel too. Disconnect it from the engine and blow air though it. If you find gas, the regulator has failed.

    5.) Fuel pressure OK, the injectors are not firing.
    A.) The PIP sensor in the distributor tells the computer when to fire the injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed.
    A noid light available from any auto parts store, is one way to test the injector circuit to see if the injectors are firing. The noid light plugs into the fuel injector harness in place of any easily accessible injector. Plug it in and try to start the engine: it will flash if the injector is firing.

    I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles. Cheap if you have the stuff laying around, and works good too.
    B.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
    C.) No power, then look for problems with the 10 pin connecter (salt & pepper shakers at the rear of the upper manifold).

    See the graphic for the 10 pin connector circuit layout.
    [​IMG]
    The injector power pin is the VPWR pin in the black 10 pin connector.


    D.) No power and the 10 pin connections are good: look for broken wiring between the orange/black wire on the EEC relay and the red wire for the 10 pin connectors.
    E.) TPS voltage exceeds 3.7 volts with the throttle closed. This will shut off the injectors, since the computer uses this strategy to clear a flooded engine. Use a DVM, a pair of safety pins, and probe the black/white and green wires to measure the TPS voltage.
    On a 94-95 Mustang, probe the black/white and grey/white wires to measure the TPS voltage.
    It should be .5-.1.0 volts with the key on, engine not running. Note that if the black/white wire (signal ground) has a bad connection, you will get some strange readings. Make a second measurement using the battery post as the ground to eliminate any ground problems. If the readings are different by more than 5%, you may have a high resistance condition in the black/white signal ground circuit.

    6.) Spark & fuel pressure OK.
    A.) Failed IAB or improperly set base idle (no airflow to start engine). Press the throttle ¼ way down and try to start the car. See the "Surging Idle Checklist for help with all your idle/stall problems.
    B.) Failed computer (not very likely)
    C.) Engine ignition or cam timing off: only likely if the engine has been worked on recently. If you removed the distributor, there is a good probability that you installed it 180 degrees out of time.
    D.) Firing order off: HO & 351 use a different firing order from the non HO engines.
    HO & 351W 1-3-7-2-6-5-4-8
    Non HO 1-5-4-2-6-3-7-8
    E.) No start when hot - Press the throttle to the floor & try starting it if you get this far. If it starts, replace the ECT.
    F. ) Engine that has had the heads off or valves adjusted. Do a compression test to make sure the valves are not adjusted too tight. You should have a minimum of 90 PSI on a cold engine.
    #2
  3. 94coupe

    94coupe Member

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    #3
  4. 94coupe

    94coupe Member

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    so I changed the distributor and it seems to start everytime but after 5 -10 minutes of ddriving it, it dies...I pull over pull the spout drive it home, I haven't had time to read anything on it im moving 1000 ks and im towing it....got a checklist for "dies when running?" anyway anything will help thanks
    #4
  5. Gearbanger 101

    Gearbanger 101 Straight Outta Locash Super Mod

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    Starting and running cold, but shutting down shortly after warm up sounds like a bad TFI module. They've got a habit of going bad after a few years. The one on your SN95 is located in the wiring harness underneath your airbox.
    #5
  6. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    See the link to a PDF document in the bottom of this code definition. It sounds like what you are seeing happen. Dump the codes and see if you get a code 14.

    Code 14 - Ignition pickup (PIP) was erratic – the hall effect sensor in the distributor is failing. Bad sensor, bad wiring, dirty contacts.

    Revised 10-Dec-2012 to add PIP diagnostic testing & Wells info

    The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. They are often heat sensitive, increasing the failure rate as the temperature increases.

    PIP Sensor functionality, testing and replacement:
    The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. A failing PIP sensor will often set code 14 in the computer. They are often heat sensitive, increasing the failure rate as the temperature increases.

    Some simple checks to do before replacing the PIP sensor or distributor:
    You will need a Multimeter or DVM with good batteries: test or replace them before you get started.. You may also need some extra 16-18 gauge wire to extend the length of the meter’s test leads.
    Visual check first: look for chaffed or damaged wiring and loose connector pins in the TFI harness connector.
    Check the IDM wiring – dark green/yellow wire from the TFI module to pin 4 on the computer. There is a 22K Ohm resistor in the wiring between the TFI and the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 22,000 ohms +/- 10%.
    Check the PIP wiring - dark blue from the TFI module to pin 56 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
    Check the SPOUT wiring – yellow/lt green from the TFI module to pin 36 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
    Check the black/orange wire from the TFI module to pin 16 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
    Check the red/green wire; it should have a steady 12-13 volts with the ignition switch on and the engine not running.
    Check the red/blue wire; it should have a steady 12-13 volts with the ignition switch in Start and the engine not running. Watch out for the fan blades when you do this test, since the engine will be cranking.
    If you do not find any chaffed or broken wires, high resistance connections or loose pins in the wiring harness, replace the PIP sensor or the distributor.

    The PIP sensor is mounted in the bottom of the distributor under the shutter wheel. In stock Ford distributors, you have to press the gear off the distributor shaft to get access to it to replace it. Most guys just end up replacing the distributor with a reman unit for about $75 exchange

    PIP problems & diagnostic info
    Spark with the SPOUT out, but not with the SPOUT in suggests a PIP problem. The PIP signal level needs to be above 6.5 volts to trigger the computer, but only needs to be 5.75 volts to trigger the TFI module. Hence with a weak PIP signal, you could get spark but no injector pulse. You will need an oscilloscope or graphing DVM to measure the output voltage since it is not a straight DC voltage.

    See http://www.wellsmfgcorp.com/pdf/counterp_v8_i2_2004.pdf and http://www.wellsmfgcorp.com/pdf/counterp_v8_i3_2004.pdf for verification of this little detail from Wells, a manufacturer of TFI modules and ignition system products.



    Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

    Dumping the computer diagnostic codes on 86-95 Mustangs

    Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

    Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

    Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

    Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

    Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
    Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

    [​IMG]

    [​IMG]

    If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

    [​IMG]

    The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

    89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.

    [​IMG]

    The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


    WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

    What to expect:
    You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

    Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

    Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

    Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

    Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
    See AutoZone Part Number: 25886 , $10
    [​IMG]



    Alternate methods:
    For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

    Or for a nicer scanner see www.midwayautosupply.com/Equus-Digital-Ford-Code-Reader/dp/B000EW0KHW Equus - Digital Ford Code Reader (3145It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $22-$36.
    #6
  7. 94coupe

    94coupe Member

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    so I changed the distributor and it seems to start everytime but after 5 -10 minutes of ddriving it, it dies...I pull over pull the spout drive it home, I haven't had time to read anything on it im moving 1000 ks and im towing it....got a checklist for "dies when running?" anyway anything will help thanks
    code 111 and 332 are the only codes i get??? i just drove 14 hours across i province and all that was chinese to me obviously i need sleep and revisit these procedures tomorrow,i know its not pip i put new distributor in it friday...unless its faulty?
    #7
  8. 94coupe

    94coupe Member

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    this problem also has caused a miss in a cylinder
    #8
  9. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Code 111 System Pass, no problems found

    Code 33 or 332 - Insufficient EGR flow detected.
    Look for vacuum leaks, cracked vacuum lines, failed EGR vacuum regulator. Check to see if you have 10” of vacuum at the EGR vacuum connection coming from the intake manifold. Look for electrical signal at the vacuum regulator solenoid valves located on the rear of the passenger side wheel well. Using a test light across the electrical connector, it should flicker as the electrical signal changes. Remember that the computer does not source any power, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit. Check for resistance between the brown/lt green wire on the EGR sensor and pin 27 on the computer: you should have less than 1.5 ohm.

    See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

    [​IMG]


    EGR test procedure courtesy of cjones

    to check the EGR valve:
    bring the engine to normal temp.

    connect a vacuum pump to the EGR Valve or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

    Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).


    apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

    if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.

    if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.

    if engine stumbled, connect EGR test jig to the hose coming off of the EGR Valve.
    Use your finger to cap the open port on the vacuum tee.
    snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
    did the vacuum gauge show about 2-5 in vacuum?
    if not the EVR has failed

    EGR test jig
    [​IMG]

    The operation of the EGR vacuum regulator can be checked by using a test light applied across the wiring connector. Jumper the computer into self test mode and turn the key on but do not start the engine. You will hear all the actuators (including the EVR vacuum regulator) cycle. Watch for the light to flicker: that means the computer has signaled the EGR vacuum regulator successfully.
    #9

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