Satan causes intermittent power loss/bucking?

Discussion in 'Fox 5.0 Mustang Tech' started by Darkwriter77, Aug 15, 2005.

  1. It could be as low as 30-32 psi while cranking or priming.
  2. Anything less than 30 psi means no go, right? I can hear it click n' hum to prime with the key, but it must be so gutless now that it won't poop out enough pressure to feed all 8 injectors. It doesn't even TRY to cough or sputter when I crank it.

    I now have in my hands a nice, shiny, brand new Edelbrock 155 lph pump kit, and tomorrow (assuming the shipment arrives as scheduled) I'll having my groping mitts all over a brand new fuel level sending unit. Turkey Day will be Horsey Heart Transplant Day. Here's to hoping all goes well, and I don't blow myself up with a random spark while the tank's out... :D
  3. yea

    i feel your waisting time throwing parts at this car... countless dollars your sinking into this problem that isnt fixing your concern,.... Im telling you right now im a ford technician and have sat here for nearly an hour reading every post on this car AND I SAY YOU HAVE AN ELECTRICAL DEMON... and nothing more... check your eec harness where it passes throught the firewall.. check the injector harness for rubbing on anything sharp... if any 12v source grounds out to the ecm it will cause exactly what your complaining about... sometimes it happens sometimes it doesnt...

    Ive recently worked on a car where you would drive the car and it would occasionally feel like it had no power, buck, jerk, shutoff, idle bad,, everything your explaining and it ended up being the Hot 12 v signal wire going to the eec relay that powers up the computer... i thought it was something ignition related and started to do exactly what your doing, new coil, distributor, tfi module.. of course i didnt buy new i had other parts laying around to try out,,, but in the end i stopped throwing parts at it and started looking electrical.. as soon as i found the short the car idled perfectly, felt stronger then ever.. all concerns disappeared.. even the dreaded cold start stopped... and foxes are known for not staying running when cold...

    give it a shot... stop throwing parts at it ..
  4. I agree its a electrical problem, i got the same problem too :Damnit: I used to have a huge surging like it had a HUGE cam in it but i hooked up a fuel pump monitor signal since I never did when i did my mass air conversion, and now it runs soo smoooth, hasnt even hinted a surge or anything, its been about 4 days since i did it and so far so good. You have an 89 i think so you should already have this and not worry about it. Where is your timing at???? is it normal, or r u getting a ridiculously high timing like me? (60 degrees advanced :shrug: ) Mine started doing this as soon as i dropped my new engine in she had this timing problem and my bucking, well the bucking really didnt show up right away it took about a 1,000 miles for the gremlin to show its face at cruising speeds. Im getting a code 18 Spout circuit grounded and i checked all those wires and theyre not grounded, have high resistance or open :shrug: Also changed the tfi module and no change. I was thinking about the ignition pickup (PIP) besides that and the maf i dont no what else it could be. If you have a friend with a stang, start swapping suspecting parts to figure out what the problem might be. Im curious to see if u have whacky timing also.
  5. I agree, I've been throwing parts at it. Many of 'em were things that were needed, regardless - injectors, cap/rotor, plugs, wires, those sorta things - and considering the miles on the chassis, I haven't really been doing any harm to it, per se, by throwing 'em on there. All parts that I haven't been sure whether or not they were defective, I've kept in a little box that I stashed in the trunk for emergencies such as the one I had the other day.

    I was convinced it was an electrical problem, too, until it finally pooped on me the other day. I'm getting spark on all 8 cylinders, but I still have a no-start condition. It's getting air, of course, so there's only one part of the Triangle of Fire that's missing: FUEL. Even if I had one or two bad injectors, it would still start ... it'd run like crap, but it would start. But as it is now, I'm dead in the water.

    Only electrical item I can think of that might also fall under this would be the fuel pump relay ... but if the pump's kicking on with the ignition, then it would seem to me that it's doing fine, no...?
  6. A failing fuel pump relay normally sets codes 95 or 96.

    Mass air conversion cars can set this code even though there is no problem. The mass air conversion requires the adding of a wire for the fuel pump sense.

    For a systemmatic troubleshooting approach, this this:

    Cranks OK, but No Start Checklist for Fuel Injected Mustangs

    1.) Remove push on connector from starter solenoid and turn ignition switch on. Place car in neutral or Park. Remove coil wire from distributor & and hold 3/8” away from 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
    E.) ECC relay next to computer - look for 12 volts at the fuel injector red wires
    F.) 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.
    G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire.
    H.) Computer

    See the following links for wiring diagrams... for 79-88 model cars for 89-93 model 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 ECC test connector and jump the connector in the lower RH corner to ground. See for a description of the test connector. 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 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.

    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.) Blown fuse link in wiring harness. Look for 12 volts at the Orange/Lt Blue wire on the fuel pump relay. The fuse links live in the wiring harness near the starter solenoid.
    F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect for fuel escaping while pump is running.

    Fuel pressure OK, the injectors are not firing.

    A.) A Noid light available from Autozone, is one way to test the injector wiring.
    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.

    a.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
    b.) No power, then look for problems with the 10 pin connecter (salt & pepper shakers at the rear of the upper manifold).
    c.) 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.

    4.) 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.
  7. Instead of dealing with sucking out gas and dropping the tank, etc., I tested some of the above stuffs first (many thanks again, jrichker). The good news is...

    Fuel pressure with key on, without cranking: 20 psi
    Fuel pressure with key on, cranking: 40 psi
    Pressure does not drop while sitting. Fuel pump relay clicks just fine., chances are it isn't the fuel pump/system.

    The bad news is...
    No spark at any cylinder. No spark from coil. Already swapped coils AND coil wires. Still no spark.

    I suck. Y'all are right. It's an electrical issue. I hate electrical bug hunts. :(

    Okay, so with handy-dandy voltmeter in hand, what shall I begin probing at next? I yanked the whole computer out, completely, trying to find this fabled relay that's supposed to be somewhere around it. I see no such animal in there. Where, exactly, is this little beastie located? Autozone listings point to "Passenger side kickpanel, below Engine Computer Control." The only thing below the ECC is a bunch of carpet lint, road dust, and a really old, crusty penny someone dropped down there ages ago. Nothing above, either, except the bracket that holds the "brain" and some sound deadener. There's about four or five multi-wire connection plugs around there, but no relays. Anyone got a pic handy?

    Things I checked:

    A.) MSD or Crane ignition box if so equipped (N/A)
    B.) Coil (MSD and OEM swapped, no change)
    C.) TFI module (new)
    D.) PIP sensor in distributor (new0
    E.) ECC relay next to computer - look for 12 volts at the fuel injector red wires (WHERE IS THIS THING?)
    F.) 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. (Checks good.)
    G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire. (Checks good.)
    H.) Computer (Hmmmm...)

    Also, is there any true way to test the computer, or is it just a process of elimination? Sure, I can blast away $90 on a reman Cardone unit, but if it's not going to get my 'Stang back up and running, then... I dunno.

    I'm so close to fixing this, I can taste it! ... er, wait, no. That's just dust in my face from crawling around under the dashboard with a multimeter... :)
  8. The ECC relay lives above the computer. It is hard to see & hard to get to unless
    you have small hands. I ended up removing the passenger side dash speaker to be
    able to see it & help get to it.

    Are you getting the 12 volts at the red wire on the injectors? If so, the ECC relay
    is working. If not, then either the relay or the fuse link that feeds it has failed.

    Are you getting 12 volts at the ignition coil red/green wire with the ignition switch
    on? If not either the fuse link or ignition switch has failed. See the second
    diagram from Tmoss for more help.

    Don't forget the TFI (even though it may be new) as a possible culprit.

    See the following website for some help from Tmoss (diagram designer) &
    Stang&2Birds (website host) for help on 88-90 wiring

    Diagram courtesy of Tmoss and Stang&2birds.

    Attached Files:

  9. Cool beans. Many thanks. Checking into it now; will have results shortly...
  10. I'm still at a loss, here. Doing some car-to-car comparisons, I get 12 volts on my Lincoln Town Car, but on the 'Stang, I'm getting nothing at the coil for voltage. I finally found that lil' bugger of a relay for the ECM, hiding behind that far-up layer of sound insulation over the top of the plastic ECM bracket. I spent 30 minutes just trying to get the friggin' connector to let go of the old one - had one hand in through the speaker hole, and the other up through where the ECM was sitting (thanks for the tip on checkin' behind the speaker, btw). I swapped on another relay to see if it would change - first a used one, then a new one. No go with either one, still no juice to the coil.

    Just for kicks, I cruised over to my store and bench-tested both TFI modules I've got. Both pass with flying colors. I know that the Wells bench tester isn't always 100% right, but I'm highly doubting that THREE modules (my old OEM, and my two new Wells units) back-to-back are bad right out of the box. Besides, I doubt it would account for there not being any voltage going to the ignition coil, anyway, as that's higher up in the food chain than the TFI, it would seem.

    Every fuse link I could find checks good for continuity - they're all in a bundle under the coil there, so it took a lot of peeling back of ancient electrical tape to get at 'em (I hate that nasty tar-like adhesive they always use). I followed back every single wire on every major connection. Only bad connection I could find was the wire leading to the push-on connector of the starter solenoid, as the plastic sleeving was dry-rotted and cracked in a few spots. I spliced/soldered in a new foot-long length of wire, but it changed nothing; disconnecting that wire completely only resulted in the starter not engaging at all, of course, so that venture was merely wishful thinking.

    So, unless the ignition switch, itself, has crapped out (doubtful, but who knows), I'm guessing it might be the computer. Weird, as I've always heard of ECM's dying while sitting still, not while you're running down the road. That, and the whole intermittent surging/power loss thing doesn't quite seem in line with it, or the way it gave about 15 seconds' notice before giving up the ghost, but ... oh, hell, what do I know. :(

    Sure wish there was a real test of some sort for the ECM. I dunno, some kinda Wells tester that just plugs into the back of the sucker and pulls a full diagnostic. Relying upon the ol' code reader hasn't gotten me far in that sense - first points me to a rich condition, then a lean one. Being that time is of the essence, and I'm sure that I can't depend upon bumming rides offa' folks forever, I went ahead and ordered an ECM today ($95 part with a $90 core, woo!); if I figure this thing out before it arrives, then no loss, I'll just return it. Otherwise, the new one's gettin' plugged in there tomorrow night. Can't figure what would kill off the computer, or what would cause it to have the whole sporadic power loss/surging problems beforehand, other than perhaps just general old age - it's been sitting in its happy home there since the fall of 1988, and it's seen 200+k miles, so who knows.

    I figure I'm officially out of options, after this. If the computer isn't the final Holy Grail for which I've searched so long, then I guess it's time to pass on the crusade to someone else and give the dealership (and another friggin' tow truck) a call. *le sigh*

    Results to be posted within 48 hours...
  11. I vote for the ignition switch. The +12V to the coil and power to energize the starter solenoid do not connect to the PCM.

    When my ignition switch acted up and I changed it out it literally flew apart in my hands when I removed it. You'll need a special torx bit with a hole in the center to get the switch out.

    Good Luck, Don
  12. Are you getting 12 volts at the ignition coil red/green wire with the ignition switch
    on? If not either the fuse link or ignition switch has failed.
    Diagram courtesy of Tmoss and Stang&2birds.

    Attached Files:

  13. Whelp, seeing as FedEx (aka SPED-Ex) has decided to delay shipment of my ECU for THREE MORE DAYS, I can give the ignition switch a shot. Not trying to sound argumentative, but I can't figure how the ignition switch would cause the power loss symptoms I was experiencing beforehand - the surging, perhaps, if it was cutting out the ignition completely off and on, but the power loss and exhaust popping...? Although it does make sense as to why I'm not getting voltage to the coil, so ... in goes a new one.

    And hey, if it fixes it, I'll gladly take a $20 fix over a $200 fix, anyday. :) Once again, will have results posted within 48 hours...
  14. New ignition switch is in. Cranks and cranks, still no juice to the coil or plugs, still no start. So much for hoping for cheap fixes.

    If the new computer doesn't do it, then it's off to Ford with it. Anyone got an industrial-sized bottle of KY Jelly I can borrow for when they surely try to tell me I need a whole new wiring harness, or some other insanely-priced item I haven't yet replaced? :(
  15. Look for a failed blue fuse link. It is the one that feeds power to the coil.

    Diagram courtesy of Tmoss and Stang&2birds.


    Attached Files:

  16. I have an extra A9L. If you are interested, PM me.
  17. Something I've been wondering the whole time I've been poking around this thing: Why the hell did Ford use these goofy fusable links instead of just using plain ol' FUSES? It seems that all the later-model cars they've made use power distribution boxes with "mega" blade style fuses and the like, and they've been using the technology since the 70's or earlier ... so why utilize some undersized pieces of wiring that you can't always diagnose as good or bad without using extra equipment?

    Another thought: if these fusible links are supposed to act as "fuses," and fuses tend not to simply wear out from age, what could've popped the one(s) that are keeping my beast from getting spark?

    Being that my parts store is crapola and, three days after the order was placed, the computer I ordered STILL didn't even have a friggin' tracking number assigned to it, I canceled the order and bought a stack of fusible links. Again, I've checked just about every one I could find - probably overlooked the one bad one causing all my problems, surely - but I figure I'm just going to replace every single one of these stupid fusible links with either new ones or I'll splice in an in-line fuse in place of it ... although that, in itself, is a puzzle, being that fusible links are usually rated by wire gauge instead of amps. Ugh. :nonono:

  18. *sounds of joyous screaming and happy-dancing*


    ...and it still doesn't start.


    ...pulling out the distributor, itself, I gave it a spin by hand. It won't turn even 1/4 around without clicking up against something. Look up inside of there, and ... *GASP!* ... the magnet across from the PIP Sensor has friggin' detached itself from its place and is sticking itself against the blades of the neato-magneto-thingy-ma-doo-hickey (whatever the hell the technical name is for that rotor-ish thing in there). Seems obvious even to an idiot like me that something like that isn't a good thing.

    Sooooo ... swapping this turd chunk out with yet ANOTHER reman'ed distributor. Dunno if this'll cure the surge/power loss issue, but at least it should get me back on the road, again.

    FINALLY, the first good news I've had in weeks! *more happy-dancing* :D
  19. *more rejoicing and happy-dancing*

    It lives again... :D

    ...and Satan still inhabits my engine bay. :(

    Back to square one again. But at least I can get to/from work again, now. :)

    Still have the new fuel pump sitting in my tool room, along with a new fuel level sending unit. Since I've pretty much ruled out the entire ignition system at this point, having replaced and RE-replaced everything there is from end to end, it's either a fuel delivery or air/fuel mix issue (caused by some errant sensor), now.

    So ... back to the original issue: random bouts of surging and power loss. Ideas?
  20. I know you've checked and cleaned a number of thing including grounds. Did you check the ground from the injector harness to the back of the driver's side cylinder head? I fought similar issues as you, i.e. bucking, missing when cold, dies on cold start. During my head swap, I was removing the injector harness and noticed the ground mentioned above was very dirty. Cleaned it and the ground strap that goes through the same bolt, problem solved. Starts very well in cold weather. Revs to 1500 and settles into a 1100 rpm idle for approx. 90 secs and then to normal idle. Give it a shot its free. Just thought you might have over-looked it.

    Good luck and stick with it.