Car dies, acts like its running out of gas

Discussion in 'Fox 5.0 Mustang Tech' started by Neltech, Jun 14, 2011.

  1. Little back story. Every once in a while when i'm really rodding on my car it would just die out. It would start back up if i just coasted for 3 or 4 seconds (5sp so its just like it was getting bump started)

    fast forward to this week. It died out of the blue at a stop light. took me 3 or 4 tries to get her back started but it did and i drove it home. the next day i started it and it died a few seconds later. fired it up and putts down the road at about 20 and it died again out of nowhere. started up after a few tries and i turned back around and parked it.

    i drove it to work today (only 2 miles) and it drove fine. then when i went to lunch i barely made it out of the parking lot before it died.

    Now it sitting in the bay at work. It'll run for maybe 10-20 seconds and then start sputtering/revving up/dying and then it will die like it runs out of gas.

    my fuel pressure regulator stays right at 40 (with the vacuum unplugged) and then the car will die and it will go down to 20.

    Fuel filter was just changed last week. I took it out today to see if the new one was plugged or something but it was just fine.

    fuel pump primes every time I turn the key.
    i get 12 volts at both sided of the wire at the inertia switch while its running, while dying, and after it dies

    the fuel pump relay wasn't clicking or anything while it dies but it click a second or two after it dies.
  2. I would suspect the TFI ignition module. You can take it off and have it tested at most of the car places, but I'm not sure they can duplicated the heat that usually causes them to act up.
  3. where is this module?
  4. It's mounted on the front of the distributor.
  5. You will need a special tool or a thin wall socket to get to the screws, but there are ways around that even.
  6. took the TFI in, tested good twice.

    its not starting at all now.

    it ran a little better when i was spraying it with carb cleaner
  7. Sounds like you are making progress....

    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 16-Jan-2011 to clarify testing the EEC relay in paragraph 1E .

    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.
    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:

    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

    AutoZone wiring diagrams: 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.

    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).
    See the graphic for the 10 pin connector circuit layout.
    The injector power pin is the VPWR pin in the black 10 pin connector.

    F.) 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.
    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. 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.
    #7 jrichker, Jun 15, 2011
    Last edited: Jun 26, 2015
  8. found the problem. bad spark plug wire from coil to distributor. thanks for the info though!
  9. Is that the wire that goes from dis. to plugs or a diff wire that go to the dist. to coil? You said plug wire an it kind of threw me off. What is it? i am in the same boat but i have replaced fuel filter, fuel TANK, fuel pump, cleaned fuel injecters ,changed plugs and wires, i have spent about a grand an got no where but made it all worse. my next thing i was goin to try was the cats an o2 sensors but they are on my set of flowmaster set i bought brand new a month ago for my red mustang an i wrecked it an bought this so i was goin to do a swap cause it was all new out of the box from a high end exhaust shop where i live. so if i can do this like you did it would be a miracle cause as of now im just about close to have done replaced so much stuff the car might be as new as it was when it sat at the dealership in 98. plez let me know what you did an how cause i am very desperate.
    #9 B Jordan, Jun 25, 2015
    Last edited by a moderator: Jun 26, 2015

  10. What model is this car? What year? What engine? It could be a Chevy dump truck for all we know.

    Proper punctuation would help to communicate what your problem is. As it stands, the run on sentence makes it difficult to understand. How do we know what you have, what you have done and what diagnostic work has been done?

    Read the Cranks OK, but No Start Checklist for Fuel Injected Mustangs I
    posted above , do the checklist in sequential order. Do the diagnostic work and you will find the problem. Throwing parts and money at it is not the answer. READ, DO, TEST, MEASURE, OBSERVE, then replace or repair what failed the tests.
    #10 jrichker, Jun 26, 2015
    Last edited: Jun 26, 2015
  11. Ok. Sorry i made this hard to understand i was just in a hurry and really didn't see that it would be that hard to understand. So my car is a 98 Ford Mustang 3.8 V6 and my prob is the exact same as the problem in the start of this trend. First things First the car only did the running out of gas kind of die out like explained from the original trend when it is hot outside an the car runs awhile. The car ran just fine all winter long as it was cold out then summer hit I stared having my problems. So before i could be driving along and it start to die an slow down i would cut the car off a second or 2 and crank it back. Then it would run a min or two an start acting up again but wouldn't never cut off on its own. The car would be taking off from a dead stop an be OK then the tach hit 4 grand an the car would just fall on its face. It wouldn't get over 25 mph to 30 mph when it is going on. So I figured that the car was starving for fuel and the first thing I went for was the fuel filter. So i changed the filter and as i did i pored the gas out of one side and the gas was clear turned to the other side and it was brown gunk. So it told me it was rust in the tank and went bought a NEW tank. I replaced the TANK and doing so i wont not going to change the FUEL PUMP. so i changed FUEL TANK, FUEL PUMP, FUEL FILTER and CLEANED AND TESTED THE INJECTORS. Doing so i made sure all was new an clean an I tested the injectors before putting them back in the car. That being said it only made my car die out more common and made it faster to messing up to the point now it cuts off. I put the code reader on the car and I seen on the code reader that the number 2 cylinder was miss firing as well as the system running to lean. As of that I did my tune up Plugs wires oil change and also changed my coil pack. As of now the changing of the coil pack and plugs wires and all the car still has a miss fire in cylinder 2. What else would cause that? As of all the things i have done an put on it has not fixed a thing. My next step to my problem was to change out the exhaust because i suspect the cats are clogging up. So I Have a set of flow masters along with new cats an o2 sensors all is about a month old. But as of the car die out as i give it throttle i have done all i could possibly think of and then some. With all that done the only out come was making the car worse. Now i am Lost on it besides doing the exhaust i have done everything in the fuel i can think of. Weather it fixed the prob or not it really all needed to be done but im still stuck with my problem . Its so bad now i cant even trust it to go out of the road of mine. Because now the car with die till the point it cuts off now. So what else could i have possibly missed? I haven't thought about the wire as he explained so what wire would i be looking for an what would i look for as my problem?
  12. B Jordan - you posted the 5.0 Tech forum. - That means that most of the guys here are primarily 79-93 Mustang guys with V8 engines. The 98 V6 is a completely different engine and electronic control system. That means you may not get a helpful answer since that isn't what most of the guys here work on.

    @madmike11157 Please move this to the appropriate forum.
  13. OK my fault i read it wrong i searched for my car year an all and this is what i got. kinda why i was wondering about the Chevy pos dump truck. but thanks for your help anyways.
  14. nm found it>