Car won't start, Not getting a pulse to the injectors

Discussion in 'Fox 5.0 Mustang Tech' started by mongol, Nov 21, 2009.

  1. So I take off work on friday to go to the dyno. I drive the car to the gas station and fill it up. Get back in the car and nothing. It turns over great but it won't start.

    In the parking lot I ...

    Can hear the pump priming when I turn the key on

    Have fuel pressure at the schrader valve on the fuel rail, drained in a bottle and cycled the key and getting great pressure.

    Getting a nice blue spark at the plugs, unhook msd box and return it to factory setup. Still good spark.

    I get my test light out and check and I have battery voltage at the injectors but the computer is not grounding them when the car is being cranked.

    So, a hour goes by and the car starts up out of no where and I drive it home. Cut it off and it will not start back. So if I let it set, later it will start back once. Let it run for a while and cut it off and it will not start back for a while. (HEAT SINK)

    This makes me think that it is a TFI module ot a Pick up problem(PIP)

    Everything that I read says that if a pip goes out I will not have a pulse but I will not have spark either.

    Then I read that if the tfi sends the signal to the computer for the pulse and the firing of the coil and the computer splits that signal and sends it back to the tfi to fire the plugs. So if I understand that if the tfi wasn't sending a signal to the computer then I would not have spark?

    I have tried two different computer with the same result.

    Tps can cause a no pulse at the injector if reading more than 3.6 volts at startup. But all is well there as its only reading .985.

    If i am wrong please let me know.
    Please help if you can, Thanks in advance Kris
  2. Cranks OK, but No Start Checklist for Fuel Injected Mustangs

    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 19-Jun-2009 to clarify ignition switch & coil power states.
    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 - 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 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 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. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire. You'll find it up next to the starter solenoid where the wire goes into the wiring harness
    I.) Computer.
    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 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:

    Sorry, the AutoZone wiring diagram links no longer work. You can navigate to the diagrams yourself via | Repair Info and select the car year, make, model and engine. That will enable you to bring up the wiring diagram for your particular car.

    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

    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

    Complete computer, actuator & sensor wiring diagram for 94-95 Mass Air Mustangs

    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 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.) 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.
    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-.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).
    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.
  3. I went to the auto parts store today and bought a tfi module and a PIP sensor. I installed the tfi module because its the easiest and it did not fix the problem. I'm going to install the PIP tommorow and see what happens.
  4. 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.

    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. Then you drive out the roll pin that secures the gear to the shaft. When you go to press the gear back on it has to lined up perfectly with the hole in the gear and shaft. I have been told that the hole for the pin is offset slightly from center and may require some extra examination to get it lined up correctly.

    Most guys just end up replacing the distributor with a reman unit for about $75 exchange

    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 and for verification of this little detail from Wells, a manufacturer of TFI modules and ignition system products.
  5. Thanks for sticking with me. I work at a shop but I'm a diesel mech. I'm not that good with this stuff but I can follow directions. Thanks, I will let you know how it turns out tommorow. Kris
  6. The situation smells of pick-up coil to me, from my experience.

    Follow JRichters advice, but I think it will lead you there anyway.
  7. i have the exact same problem as you do, except i didnt have spark, so i installed my msd 6al box and distributor and i had great spark but my injectors still werent working, i have great fuel pressure but as i said the injectors are not working. i also need some help haha
  8. Will your car start once it sits for a while or does it never start?
  9. no it doesnt.
    im just now finishing my engine build so now im tryin to get it started
    the previous owner of the car had it carburated so he ripped out the wiring harness so when i got it i put a computer and wiring harness back in and i went to try and start it and my fuel pump wouldnt turn and i had no spark so i hot wired my fuel pump to a switch real fast just to see if it would start and i put my msd 6al box and msd distributor in....
    so now i finally have fuel pressure and spark but my injectors are not working

    any idea what the problem is? lol i think maybe the computer or something is not grounded out

    i know this is more of a problem then what yours is but this is my problem lol
  10. Computer ground is located behind the factory battery, on the inner fenderwell. Another is located right below the ECM itself.
  11. jricher,

    I installed the new reman distributor today and it did not fix the problem. BUT...

    In the later part of your first post is say that if the car starts when the pedal is mashed to the floor than it is the ect sensor.

    My car does the same thing but guess what. When it doesn't start if I mash the pedal to the floor ot starts every time.

    Is there any way to test the ect? Thanks Kris
  12. Dumping The computer diagnostic codes on 86-95 Mustangs

    Revised 19-May-2009 to update drawing for dumping the codes on 86-88 Mustangs with no check engine light.

    Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

    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.

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

    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 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.

    Here's the link 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.

    See Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical



    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.


    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.


    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.

    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.

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

    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 Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

    Code 21 or 116 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor.
    Note that that if the outside air temp is below 50 degrees F that the test for the
    ECT can be in error. This code may go away as the engine warms up, so don't dump the codes
    on a cold engine

    The ECT sensor has absolutely nothing to do with the temperature gauge. They are
    different animals. The ECT sensor is normally located it the RH front of the engine in
    the water feed tubes for the heater.

    The ACT & ECT have the same thermistor, so the table values are the same

    ACT & ECT test data:

    Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate

    Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

    Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is
    a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower
    intake manifold, the voltage readings will be lower because of the heat transfer.

    Voltages may be measured across the ECT/ACT by probing the connector from
    the rear. A pair of safety pins may be helpful in doing this. Use care in doing it
    so that you don't damage the wiring or connector.

    Here's the table :

    50 degrees F = 3.52 v
    68 degrees F = 3.02 v
    86 degrees F = 2.62 v
    104 degrees F = 2.16 v
    122 degrees F = 1.72 v
    140 degrees F = 1.35 v
    158 degrees F = 1.04 v
    176 degrees F = .80 v
    194 degrees F = .61
    212 degrees F = .47 v
    230 degrees F = .36 v
    248 degrees F = .28 v

    Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.

    50 degrees F = 58.75 K ohms
    68 degrees F = 37.30 K ohms
    86 degrees F = 27.27 K ohms
    104 degrees F = 16.15 K ohms
    122 degrees F = 10.97 K ohms
    140 degrees F = 7.60 K ohms
    158 degrees F = 5.37 K ohms
    176 degrees F = 3.84 K ohms
    194 degrees F = 2.80 K ohms
    212 degrees F = 2.07 K ohms
    230 degrees F = 1.55 K ohms
    248 degrees F = 1.18 k ohms

    Diagram 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 Mustang FAQ - Engine Information

    Ignition switch wiring

    Fuel, alternator, A/C and ignition wiring

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

    Vacuum diagram 89-93 Mustangs
  13. Got home today and checked for codes. I got a code 15 then a ten second pause and then I got a code 96.

    Code 15 says ecm processor read only memory failed self test. ( this is common with a custom chip I hear in which I have)

    Code 96, says fuel pump seconday circuit failure.

    Whats a good place where i can find a trouble tree to find out whats up. Or is there anything that I can do?
  14. Well guess what. I found that the code 96 can be because I lost power to the fuel pump relay at one time or another. Guess what, I have been playing with the enertia switch so I bet thats were that code is coming from. I guess I will have to wait until tommorow until I can do a running test.
  15. I did notice something last night though that I hadn't before and thats that all the plugs are BLACK AS COAL!

    Now I got to figure out if thats because of the condition I have or I have the condition because of the tune fouling the plugs?
  16. Hey guys well I learned a very valuable lesson today. NEVER use a test light as a noid light. I'm not saying that it may not work but in my situation it did not. This whole time I have been chasing a no injector pulse for nothing. Today on the way home from work I picked up a noid light and guess what. The injectors are firing even when the car won't start. I also have spark, but my plugs are black and soaked with fuel. I believe that I am having the problem of hard or no start because the frickin plugs are fouled.

    I think but I do not know yet.... The spark plugs fouled because of the tune was set to rich for a saftey factor. Take it to the dyno send the results and he reprograms the chip to back off the fuel off and presto. Perfect running car. I'll contact the tuner to see if he agrees.

    I also went ahead and bought a new ect for insurance. What do you guys think?

    Is this a possiablity. I have ran koeo and koer test multiple times with no codes.
  17. LOL......You sure the bulb in the test light is good? Used one many many times for a noid light.

    You might need to remove the chip and then run the KOER test while the engine is warm. ECT is a possiblilty for running rich.
  18. Yeah the test light is good because I tessted before I went back out to the car the day it broke down. This is by no means a nice test light though. Just my luck I guess.

    I'm putting in the new ect weather it needs it or not. The one for the computer is the one in the meatl tube correct? Thanks
  19. Pull all the plugs and clean them or put new plugs in.