HELP no spark off coil!!

Discussion in 'Fox 5.0 Mustang Tech' started by Teal_Deal, Feb 1, 2008.

  1. ok so i was driving to school yesterday when the car just completely died. now the car is turning over and Its getting fuel but no spark. so i replaced the coil. that wasnt it. so i looked on here and people were saying to replace the TFI sensor so i did that. still nothing. im running out of ideas of what it could be. there is no sparking coming from the coil but i have put 2 different ones on and nothing works. when i checked with the multimeter it said that there was 12v going to the coil but im not really sure on how to use the thing i could be doing something wrong cause that wouldnt make sense. thanks guys.
  2. ok so just messed with multimeter and the plug going into the coil has 12v on both the positive and negative sides when the ignition is on. is this normal?:shrug:
  3. Use a test light biased across the electrical connector to the coil. DMM's give inaccurate readings for a test like you're doing.

    See Jrichker's no start checklist for a systematic means of testing. It will save you money in parts swapping.

    Good luck.
  4. Cranks OK, but No Start Checklist for Fuel Injected Mustangs

    Revised 29-Jun-2007 to update TPS testing procedure for 94-95 Mustangs

    All text applies to all models unless stated otherwise.

    Note: 94-95 specific changes are in red

    1.) Remove push on connector from starter solenoid and turn ignition switch on. 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.) Coil
    C.) TFI module
    D.) PIP sensor in distributor. The PIP sensor supplies the timing pulse to trigger the TFI and injectors. See paragraph 5A - a noid light will tell if the pip is working by flashing when the engine is cranking.
    E.) No ECC or computer power - ECC or computer relay failure
    86-93 models only: ECC 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.
    F.) No ECC 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.
    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 with the switch in the Run position. No 12 volts and the ignition switch is faulty. If 12 volts is present in the Run position, then the fuse link is blown.
    94-95 models only: Check inside fuse panel for fuse #18 blown – 20 amp fuse
    H.) Computer
    J.) 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 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.

    See the following links for wiring diagrams... for 79-88 model cars
    Computer/fuel pump/ignition wiring diagram, 86 model
    Computer/fuel pump/ignition wiring diagram, 87 model
    Computer/fuel pump/ignition wiring diagram, 88 model for 89-93 model cars
    Computer/fuel pump/ignition wiring diagram, 89-90 cars
    Computer/fuel pump/ignition wiring diagram, 91-93 cars for 94-98 model cars

    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:
    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 5-20 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.

    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.) A noid light available from any auto parts store, is one way to test the injector wiring.
    The noid light plugs into the fuel injector harness in place of any easily accessible injector. Plug it in and it will flash if the injector is firing.
    B.) 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.
    D.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
    E.) No power, then look for problems with the 10 pin connecter (salt & pepper shakers at the rear of the upper manifold).
    F.) No power and the 10 pin connections are good: look for broken wiring between the orange/black wire on the ECC relay and the red wire for the 10 pin connectors.
    G.) 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-.99 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 (no airflow to start engine). Press the throttle ¼ way down and try to start the car.
    B.) Failed computer (not very likely)
    C.) Engine ignition or cam timing off: only likely if the engine has been worked on recently).
    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.
  5. I say just pull your distributor and buy a new or reman from auto zone, same thing hapened to my car and people kept saying to chech this and check that, but I couldn't find anything wrong with mine, so I just bought the new distributor and it fired right up, I think there around 60 dollars, just kep your caps and tfi module.
  6. im with dcurtis, i had a problem like this and it was the eye in the dizzy that tells the tfi to signal the coil to fire. i had the magnetic eye fixed but i still think i need a new dizzy.
  7. Sry to bring up an old post. But Im running threw the no start list and im at the point on checking my tps. Checking my ohm rating of my ground wire (black/white) and its reading like 5.0+. Aswell as my injectors are only at 8-9v +-. I checked the ground on my eec sanded off old pant and made sure it was clean metal. Battery is in the trunk i have 1 ground running to frame and 1 to roll cage. and i have solid motor mounts.

    When i spray some engine starting fluid the car seems to want to start realy bad. I guess i should mention this is a explorer motor i put the tfs stage 1 came in, with usual bolt ons. Its a reman distributor from advance. Now ive never done any of this type of work but ive spent allot of time watching and reading on how to. The car hasn't ran in about 12 years. I chopped up my old harness cause i decided to go carb. After a few years decided to go back.
  8. I guess i should also add im gotting 8-9+- volts off the orange white wire for some reason. When im reading it should be around 5
  9. The maximum resistance on The black/white wire should be less than 1.5 ohms. Be sure to take rsistance readings with the ignition switch off.

    Check and clean the salt & pepper 10 pin electric connectors. See for the how to do it with pictures.

    See the graphic for the 10 pin connector circuit layout.
    The injector power pin is the VPWR pin in the black 10 pin connector.
  10. Thanks i will try to clean them after work. But i checked by the computer and was still only getting 8v out of it at the red wire. The computer is out of my friends running car so im 99% sure thats good.
  11. ok just checked with key off 1.o ohm. silly me, didnt really think that mattered.
  12. Ok all is clean. still only seeing 8v on both wires going to the injectors. car started for a second with a shot of starting spray so i know this has to be a fuel problem. Im running all braided line up to a professional products fuel rails and regulator both the rail mounted fuel pressure gauge and cock pit gauges are reading 35 lbs.
  13. Are there fresh batteries in your voltmeter?

    If there isn't 12 volts on the red injector wires, you have a low voltage condition in the power feed circuit for the computer. The computer power feed relay also feeds the red wires for the fuel injectors. There is a voltage regulator inside the computer to supply 5 volts to all the computer circuitry and some of the sensors. If the voltage drops off too far, the voltage regulator inside the computer quits working and you will see strange voltages on the TPS ,MAP/Baro and EGR sensors.

    Diagrams courtesy of Tmoss & Stang&2birds



    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.

    Ignition switch wiring

    Fuel, alternator, A/C and ignition wiring

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

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

    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
  14. Ok after alot of yelling, kicking, and screaming.. Somthing told me to try my old eec relay. and wham! 12v to injectors!. still doesnt start though so im gonna buy a noid light tomorrow and make sure it flashes. And if thats good im gonna pull my timing cover off again and make sure i set my cam gear timing correct.
  15. Get a new computer;)
  16. Well like i said the computer is out of my friends running car so its not that.
  17. pip sensor in dizzy
  18. No flash on noid light. Tried 2 different distributors (reman from advance)
  19. Ok news update. so i did some more readings on my tps, and blk/w ohm reading with key off is 5.69. now ive moved the battery to my trunk so i cant get a negative lead straight from that but i went to motor. also pulled a wire straight from there and same reading. Ok now my volts from orange to blk/w was .15v but from orange to motor was 9.67. now my volts from blk/w to green was .13v. but from motor to green was 9.98v. i also did the blk/w to green and move the throttle and there was only a .8v change at wot.

    Now obviously it seems theres a ground issue here. Ive check all the grounds i could find. Also my haynes manual says pin #20,40,60,49 are all grounds. So i did a ohm reading from them to my eec ground and 2,49 was .02 ohm. pin 40 and 60 are showing 47.5 ohm.. Can i just jump all these together for 1 known good ground. This tps issue would have to be the reason my injectors arnt firing since its reading so high?
  20. Might be "hall effect" issue, its inside ur distributer