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  1. #26
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    qikgts's Avatar
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    Quote Originally Posted by danco86 View Post
    unfortunately does not give a very good description s to where this splice (s127) is.
    I could be wrong but I have a sneaking suspicion that this splice is going to be found in the EEC harness on the pass side, under the hood, right around the tape out for the AC pressure switch.
    '85 GT

  2. #27
    FEP Super Member erratic50's Avatar
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    The dealer said the power lead we were blowing the fusible link on was the fuel pump power. Wrong- it was the EEC power which of course kills the fuel relay.

    I added the blow/glow fuse to the blue 20 ga link wire.

    I found there is also an auto-reset breaker before the fusible link going to the fuel pump that we kept tripping. We found several problems on the fuel pump circuit that are now all fixed and this part is now all fine.

    The fuel pump relay was intermittently shorting causing the EEC fuse to pop immediately when the key was turned on. Fixed this with a new relay.

    Then we drove it for a week trouble free before it started blowing EEC fuses again.

    Trouble corresponded with a rain storm. I found a soaked EEC and relay due to shoddy workmanship. The relay just hung off the relay wires and antenna cable instead of being secured to the bottom of the dash. The antenna lead didn't have a proper seal or drip loop - that's where the water was coming in.

    The relay was full of rain water. The EEC looked like it was found at the bottom of a lake but was still somehow working.

    We pulled the factory soft tune VR1 EEC-IV and swapped in a known good aggressive tuned VM1 EEC-IV and a new EEC relay.

    Also added a new ignition switch because the old one was well worn and occasionally had failed to act properly when we first got the car.

    I thibk the behavior stinks of an ignition problem so I bought all the stuff to redo it but before I installed any parts I added a fuse at pin 4 of the EEC relay that's smaller than the fuse under the hood. It's blowing the fuse at the EEC relay which says to me that something is wrong on the EEC side.

    Chasing lots of gremlins on this car. The previous owner screwed up everything he touched- literally. How damn hard is it to cut a hole in new carpet for the fuel relay or seal up an antenna wire, for example.

    I didn't follow your post entirely Dan. Are you saying that I missed a wire and there is something ignition related pulling power from the EEC? I ask this because my money was on a faulty ignition module overworking the coil and this causing the problem.

    I thought surely I had it when I found the AC wire melted.

    I know we have been battling multiple things because with each "fix" the condition improves but it's still not cured. It does let you put in a 10 amp fuse under the hood and a 5 at the EEC and not blow either instantly like it did when we started fighting this and 30a was the only thing we could keep in it under the hood.

    one thing that's interesting is it doesn't seem to matter how nasty or nice you drive it - 20 miles is the outer limit of what you get on a fuse.

    I might take the distributor out and put in all new stuff just for my own satisfaction in knowing the parts are new. I've had decent luck with the top of the line Autozone ignition parts in mine. I found the value craft stuff to be pure garbage.

    i wonder which breakout box is correct for the 86 5.0L EFI running a speed density EEC-IV. At this point I'm willing to buy one.
    Last edited by erratic50; 04-11-2017 at 12:10 AM.

  3. #28
    FEP Super Member erratic50's Avatar
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    Eventually is going to have to hurry up. I am way beyond fed up. I'm working 100 hour weeks out of town on the road then spending every day of my weekends fighting with a blasted broken mustang that is my son's daily driver. I am at my limit!

    If anyone is in the Omaha NE area that's talented with this stuff and wants to make a buck or two I'd gladly pay cash money by the hour for a fresh set of eyes.

    It seems like at the Ford dealers nobody knows what they are doing on these old cans anymore except for the old guy in the corner that's weeks from retirement and doesn't care to work on an 80's classic anymore. Let's face it - the car is nearly as old as the average mechanic on staff that's still turning wrenches instead of chasing parts or advising.

    Fresh eyes might just might be what the doctor ordered. I feel like my son and I are looking past the obvious subconsciously right now because we've been fighting to too long.

    one observation we made yesterday is that none of this was happening until a few weeks after we had welded in subframe connectors. I don't see any correlation-- but who knows.
    Last edited by erratic50; 04-11-2017 at 12:20 AM.

  4. #29
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    If I was troubleshooting this here are some options I would consider doing now. Not listed in any particular order.

    1- Find the splice mentioned above and simply do a temporary install of five fuse holders, one for each circuit powered up from that EEC relay. The one that blows would indicate the branch with the issue.

    2- Disconnect all of the solenoids ID'd by danco in his post and ohm them out and see if you can find an issue with one. If that didn't show a bad one, then drive the car on a "20 mile" test with all the solenoids and the WOT AC relay disconnected. If the fuses are still good after that, then repeat the "20 mile" drive but this time I'd add in one (any one) of the solenoids/AC relay. If the fuses you have already added in the car (the 10 and 5) survived then I'd repeat this test drive process adding in another solenoid until you find the troublemaker. The only other thing I would do is up the fuse sizes, reasonably, as I added more solenoids back in. I think this would be a legit test based on you saying it's now consistently doing the same thing over and over on the "20 mile" drive. If the fuses still don't blow, then I'd start looking for a wire fed by that splice, being intermittently shorted to ground as it's unlikely that injectors on their own would draw enough current to pop a 30 amp fuse. The same can be said for the fuel pump relay coil, the IAC and the individual pins on the EEC.

    3- Disconnect the battery, disconnect the computer, disconnect the fuel pump relay, all the solenoids, the WOT AC relay and start ohming out every branch of the circuit.

    4- Make the kid do all this. It's his car. lol
    '85 GT

  5. #30
    FEP Senior Member danco86's Avatar
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    Now that you've explained the fuel pump relay scenario. That all makes sense.
    In my post I was saying that I agreed that the issue wasn't ignition switch related. Your relay is staying energized. The only way to burn up the coil would be by applying too much voltage to it, or not enough so it would be chattering on/off. Neither is the case here from the sounds of it.
    The 9 things I listed are all supplied power by the eec relay. So I suspect one of these circuits is causing this. Hence the idea of finding the point where the wire from the relay splices into all the seperate circuits, then fuse each individually to determine which one is causing the issue.
    The fact that it lasts 20 miles or so makes me suspect it would be the tab/tad solenoids, or egr, as these are temperature dependent.
    Do the fuses last less time once the engine is at operating temperature?
    Does the car still have the thermactor system intact? Maybe try unplugging the tab/tad solenoids and see if the fuse holds. I'm just trying to think of quick, possibly easy checks for now. Having them disconnected will not affect the operation of the motor, just might display codes - I think.
    As far as taking anything this old to a Ford dealer, you are bang on. None of these guys nowadays knows anything about these cars unless a laptop can tell them. You have to find someone who specializes in these cars nowadays.
    I wish I could link you the pages of the evtm so you could see the circuits and splice for yourself. However the link I posted earlier is a fairly accurate single line diagram of what the eec relay feeds.
    Dan

    http://vb.foureyedpride.com/showthre...ng-GT-restomod


    1986 Mustang GT Cobra
    Lotsa stuff, lotsa work. Check my thread above.

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  6. #31
    FEP Senior Member danco86's Avatar
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    Yeah, the manual says it's by the t/o,as I'm sure you've read. I can't think of what that is. You?
    Dan

    http://vb.foureyedpride.com/showthre...ng-GT-restomod


    1986 Mustang GT Cobra
    Lotsa stuff, lotsa work. Check my thread above.

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  7. #32
    FEP Senior Member danco86's Avatar
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    Quote Originally Posted by qikgts View Post
    I could be wrong but I have a sneaking suspicion that this splice is going to be found in the EEC harness on the pass side, under the hood, right around the tape out for the AC pressure switch.
    Ha. My last post was referring to this.
    Dan

    http://vb.foureyedpride.com/showthre...ng-GT-restomod


    1986 Mustang GT Cobra
    Lotsa stuff, lotsa work. Check my thread above.

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    2012 F-150 Ecoboost Screw FX4

  8. #33

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    I had a bad inertia switch once. Somehow it was grounding randomly. The car always had a bit of a miss and then randomly cut out. Turns out into the inertia switch was 12v and out was about 8v. I ended up bypassing it and the intermittent miss went away, probably low fuel pressure.

    Here's what I would do, you know you have a fuel pump feed problem. You have a fuse going to the eec relay. This in turn trips the fuel pump relay and then hits the inertia switch and then goes to the fuel pump. You could easily replace just the 12v feed wire going to the inertia switch if you can find a short in it, or maybe just a temp wire to rule it out. You could also jump the fuel pump relay to be always on and check the power in and out. It should not get any lower voltage and you can just stick a paper clip in it.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  9. #34
    FEP Super Member erratic50's Avatar
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    Thanks for all of the ideas guys!

    Any further details on where to insert fuses - maybe a picture or a diagram?

    As time permits we will dig in. I just keep going back to the areas I know the previous owner screwed with because he did such a terrible job on everything he touched.

    The only time the fuel pump relay kicks off or the fuel pump stops now is when we lose power at the EEC-IV. I'm confident in the repairs we made there except we still don't know why the fuse I added at the ECU relay going to the ECU blows.

    Tempting to disconnect the wire going from the ECU to the inertia switch at the ECU then make the pump always on temporarily. That's the best wire to suspect because it passes right through one area where the previous owner messed with. Just thinking maybe I missed some damage?

    If that's not it I'll have no choice but to deep dive on the under hood circuits. I think we will start by unplugging anything not absolutely critical.

    While I do have another 1986 in the garage that runs great I'd hate to end up with two broken cars.

  10. #35
    FEP Super Member erratic50's Avatar
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    I spoke with a service advisor at Woodhouse while having one of our Lincolns worked on after mixing it up with a pot hole. $1100 later it has a new rim and doesn't shake anymore. Arg
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    I'm told one of their mechanics has the required breakout boxes for SD EEC-IV and LOVES working on these old EEC-IV cars - especially the old fox HO Mustangs. I'm going to try some stuff this weekend because the car has seriously torqued us off - but it's good to know there are options.
    Last edited by erratic50; 04-12-2017 at 09:56 PM.

  11. #36
    FEP Senior Member danco86's Avatar
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    Cool. Please keep us posted to the results. I am very curious as to what this will end up being.
    Dan

    http://vb.foureyedpride.com/showthre...ng-GT-restomod


    1986 Mustang GT Cobra
    Lotsa stuff, lotsa work. Check my thread above.

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  12. #37
    FEP Super Member 84StangSVT's Avatar
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    Quote Originally Posted by erratic50 View Post
    If anyone is in the Omaha NE area that's talented with this stuff and wants to make a buck or two I'd gladly pay cash money by the hour for a fresh set of eyes.

    Fresh eyes might just might be what the doctor ordered. I feel like my son and I are looking past the obvious subconsciously right now because we've been fighting to too long.
    I didn't see this thread before and I'm in the area, but I'm not very talented.

    Seriously though, I might be able to help look things over and trace some things out with you guys if you wanted. You are 100% correct that sometimes you can stare at something too long and overlook the obvious. I've done it plenty with mine. I might have some time Friday evening or Saturday, after that I will be out of town all next week for work and moving into a new house the following week.
    Brock
    1984 Mustang LX Convertible 3.8L V-6/Auto (SOLD)
    1984 Mustang GT Hatchback 5.0 V-8/5 Speed

    I'm an FEP Supporter and proud of it. Are you?

  13. #38

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    Quote Originally Posted by erratic50 View Post
    I spoke with a service advisor at Woodhouse while having one of our Lincolns worked on after mixing it up with a pot hole. $1100 later it has a new rim and doesn't shake anymore. Arg
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    I'm told one of their mechanics has the required breakout boxes for SD EEC-IV and LOVES working on these old EEC-IV cars - especially the old fox HO Mustangs. I'm going to try some stuff this weekend because the car has seriously torqued us off - but it's good to know there are options.
    Just beat it back straight and start a collection. Once mom hits 3 more potholes you'll have 20" Lincoln rims for your fox

  14. #39
    FEP Super Member erratic50's Avatar
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    Totally!

  15. #40

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    With the help of 84StangSVT, erratic50 and I were able to identify issues with the connector on the ECU ground (after the ring connector) and a bad engine ground. We redid the ground, reusing the factory location (previously it was using the bolt by the A/C) and also tying it to the body using the convertible brace that attaches to the K member. And we strung a new wire going from the splice point, to the battery, for an ECU ground. We took it for a test drive, and while it did not leave us sit, I would like to test it for a week or two so I know if the results are conclusive. I would once again like to thank 84StangSVT for coming and being a fresh set of eyes. The help is greatly appreciated.

  16. #41
    FEP Super Member JTurbo's Avatar
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    Wow - interesting thread. Fingers crossed that you guys got it fixed.

  17. #42
    FEP Super Member erratic50's Avatar
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    84StangSVT - it was a real pleasure to meet you!! I like your 84 - it's coming right along.

    Noticing the car was showing resistance between the battery and its grounding locations was a HUGELY important find. That means that the stiffening cap could aggressively try to recharge from whatever gives the path of least resistance- even if it's the ECU related circuits and the ECU ground lead is nowhere near big enough for that type of current which may have been causing a ground loop style high current situation.

    Was really cool to be able to walk back and forth between an 84 and two 86's and see the differences and make decisions about how to do the best possible fix. Grounded battery to block to core support with heavy cable has made a real difference. The headlights are way brighter too BTW.

    Who would have ever thought that a ground cable to the AC bracket would show massive resistance while going to the block doesn't. Also who would have thought the factory ground connector for the ECU wound have been corroded and loose inside and the engine to body would have showed that much resistance on the flex cable even though it appeared intact.

    Let me know if you ever need anything. Help moving stuff, a buddy with a chain, etc. Also if you want to hit a local show or cruise together. I enjoyed turning wrenches with you on the old four eyed ragtop.

    Very grateful for a fresh set of eyes. Everything passed visual inspection with flying colors but that fluke meter of yours told a way different story. Awesome!

    .
    Last edited by erratic50; 04-16-2017 at 12:06 AM.

  18. #43

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    Quoting myself from post #13

    "Double check and clean the ecm ground on the firewall near the battery. I had a baddly corroded wire that kept blowing fuses, but caused by the ground"

    All joking aside, hopefully you got it licked. These cars are pretty simple and there is a ton of information out there. The proper tools and knowledge and you can fix anything. Too bad you guys are so far away.

  19. #44

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    Thank you for mentioning the ECU ground. I wouldn't have even known what that was had you not brought it up. When you mentioned it I took the bolt loose and inspected the connection between that lead and the car, but The bad ground between the battery and the engine (and thus battery to body), in conjunction with the bad connector after where the ground bolts to the body seemed to be a major gremlin. Ohmning out the ECU ground along the fender yielded nothing extraordinary with the leads disconnected, but the connector looked to be every color of green imaginable (and maybe some that arent?).

  20. #45
    FEP Super Member erratic50's Avatar
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    Hind site - watching the amperage numbers on the wires would have pinpointed this quickly. Ohms did show minor inconsistency but it didn't really tell the story. Wiggling wires while measuring amps did.

    my money is if we removed the stiffening cap the problem would have stopped popping fuses but the car still would have cut out at times.

    My recommendation as I look at this now - cut the connector out from fender ground bolt to the funky 4 wire "smash together" connection. Grab a loop connector and a nut that fits on the negative battery post. Smash the loop between the nuts, crimp and solder in a nice heavy wire from the loop to the wires. Add a ground cable between the factory ground attachment point and the core support or K member.

    so far so good on road testing.
    Last edited by erratic50; 04-17-2017 at 12:18 AM.

  21. #46
    FEP Senior Member danco86's Avatar
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    I upgraded my grounds when I rebuilt my car and converted to the 3G alt and did the H1/H4 headlight upgrade.
    I ran #4awg from the battery to the block/block to fender apron an both sides, tied the ecu ground to the same point on the apron (shown in earlier post) and from block to alternator housing, as well as heads to block and to firewall using normal braided grounds. I then upsized my headlight grounds and bolted them to the rad support. Well worth the effort. I hope you have indeed found your issue.
    Good luck
    Dan

    http://vb.foureyedpride.com/showthre...ng-GT-restomod


    1986 Mustang GT Cobra
    Lotsa stuff, lotsa work. Check my thread above.

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    2002 F-350 7.3 Powerstroke crew 4X4
    2012 F-150 Ecoboost Screw FX4

  22. #47
    FEP Super Member erratic50's Avatar
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    I may eventually upgrade to a better alternator as well. Mine is a 65amp currently and if I crank up stereo for extended periods of time the amp/hour rating on a stock sized battery gets exceeded and the cores melt down plus my car browns out.

    Ive ran 1000-1100 CCA batteries in it since the 90's to make the lackluster charging tolerable.

  23. #48

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    I've put just shy of 150 miles on the car since we redid the grounds. Symptoms have not resurfaced in this time, so I am as comfortable as I will be in calling this issue fixed. I would imagine the bad ground on the radio that caused me to spice into the cigarette lighter ground is probably solved, and my head lights and gauges are night and day brighter.

    Here in a bit Ill probably swap out my 30A fuse (replacing the 20GA fusible link) and the 15A fuse (at the ECU relay) for either 15/10 or 10/5 respectively. At idle this circuit only pulls ~3A, so the fuses I'm currently running are far from optimal. Currently just happy to have the four eyed back on daily duty.

  24. #49
    FEP Super Member erratic50's Avatar
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    Got a scary reminder to watch yourself this evening.

    Someone in tried to car jack GliDeThuNDeR while he was in downtown Omaha. The team of guys that tried it were quickly reminded what hauling ass looks like as he was on the stick and paying attention. They were vaporized in the rear view before they could get their guns pulled out of their waist bands fortunately.

    I've been there myself and am happy that I taught my kids what to watch out for. NO fun!

    Thank god it didn't decide to start this fuse blowing crap again this evening!

  25. #50
    FEP Super Member 84StangSVT's Avatar
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    Quote Originally Posted by GliDeThuNDeR View Post
    I've put just shy of 150 miles on the car since we redid the grounds. Symptoms have not resurfaced in this time, so I am as comfortable as I will be in calling this issue fixed. I would imagine the bad ground on the radio that caused me to spice into the cigarette lighter ground is probably solved, and my head lights and gauges are night and day brighter.

    Here in a bit Ill probably swap out my 30A fuse (replacing the 20GA fusible link) and the 15A fuse (at the ECU relay) for either 15/10 or 10/5 respectively. At idle this circuit only pulls ~3A, so the fuses I'm currently running are far from optimal. Currently just happy to have the four eyed back on daily duty.
    AWESOME! I hope that it continues to be trouble free and the issue never comes back. I hate electrical gremlins.

    Quote Originally Posted by erratic50 View Post
    Got a scary reminder to watch yourself this evening.

    Someone in tried to car jack GliDeThuNDeR while he was in downtown Omaha. The team of guys that tried it were quickly reminded what hauling ass looks like as he was on the stick and paying attention. They were vaporized in the rear view before they could get their guns pulled out of their waist bands fortunately.

    I've been there myself and am happy that I taught my kids what to watch out for. NO fun!

    Thank god it didn't decide to start this fuse blowing crap again this evening!
    That sucks! I'm glad that the outcome was good and the car didn't decide to act a fool like the guys downtown. It's a scary deal to be in and not one I wish on anyone. I myself have been a victim of attempted carjacking, and the outcome was not so pleasant on my end. While I did keep my car and left the fool standing in dust and tire smoke, I also took a bullet to the chest and was in ICU for a few days. I got lucky as the bullet missed the main artery in the chest and arm by a width of a human hair, but it was an ordeal that I will never forget and hope to never have happen again.

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    Stay safe out there and always be aware of what is going on around your car. Again, I'm glad he got away unharmed.
    Last edited by 84StangSVT; 04-20-2017 at 09:51 AM.
    Brock
    1984 Mustang LX Convertible 3.8L V-6/Auto (SOLD)
    1984 Mustang GT Hatchback 5.0 V-8/5 Speed

    I'm an FEP Supporter and proud of it. Are you?

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