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  1. #1
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    Default New guy with an electrical problem--maybe several electrical problems

    Hello--68 year old, life-time Ford fan, stumped by electrical problems.
    Car is 1986 Mustang GT. My 40 year old son bought this car a few years ago with hopes of restoring it-with my help. (Yes, i was flattered!)
    But then ( tell me if you've heard, or lived this story before)...wife got pregnant, job responsibilities increased--in short no time, and no $$ for the Mustang. I put a new convertible top on it, more as a gesture toward preservation than restoration. Until recently, the car ran and drove--solid performer, and essentially stock--no poorly done boy racer mods.
    I was cleaning it up, and then i had to replace a brake line. I was hoping to get to the Ford Carlisle weekend, but ran out of time. ( Wasn't that a great show!)
    Then, with the car sitting on my lift, I started it to drive it outside and electrical problem #1 hit. Three seconds after starting, the wipers go into intermittent mode, and the dash amp meter audibly pegs to the discharge side. This cycle continues, but I did not keep it running long, maybe 30 seconds. If I pull the rectangular plug from the top of the alternator, the problems both stop--but of course, the car is running on the battery. If I turn the key to "ON" with the engine not running, the problems do not occur--with the alternator plugged in, or not. I then unplugged the W/S/W harness, and the multi-function lever harness from under the steering column--no change. I even removed the W./S/W switch--no change.

    While this was going on, electrical problem #2 raised its ugly head... Now the car is a "No Start". It cranks normally, but not a hint of trying to start. I removed the air intake hose from the throttle body and dumped in a little gas, and it immediately started and ran for 2 or 3 seconds. OK, so the problem is lack of fuel, right? Ignition side seems to be OK.

    One more observation....After I tried cranking for 10-20 seconds, I listened under the hood and heard "clicking" sounds. Almost like a relay, but also like when the engine sheet metal heats up and makes those little crackling sounds. I removed the battery cable, and the clicking continued, so its likely NOT electrical. Is it related to the other issues, or just a false lead?

    I did check the fuel pump shut off in the trunk, and the button was depressed--not raised as if it had triggered. I have some hearing loss, so i am not certain I hear the fuel pump run, but I think it runs for a couple of seconds when I switch the key to "ON".

    I wanted to check the fuel pump pressure, but I can't even find the schraeder valve connection, nor the fuel pressure regulator. Where did they bury them?

    I am out of my element on the SEFI stuff. Give the ubiquitous Ford 2V or 4V carb, and I know what to do. I do appreciate that the SEFI gets more power from less fuel, and thats all good, but its just too new for my experience.

    I have played around long enough, now its time to ask for help from the guys and gals on this forum.

  2. #2
    FEP Power Member Ourobos's Avatar
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    Shrader valve is on the fuel rail, beside the regulator, near the EGR.. Harder to reach than the 87+ but doable.

    I'd suggest checking the ignition switch on the column, see if it's separated. Requires you to remove the column cover, 15 minute job. Worth replacing with a quality motorcraft part if original and 30 years old regardless.
    1986 CHP SSP Coupe

  3. #3

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    X2 sounds like a classic ignition switch, which also plagued the last of the carbed ford trucks btw.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  4. #4
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    Is there a way to test the ignition switch before replacing it?

  5. #5
    FEP Super Member 84StangSVT's Avatar
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    Quote Originally Posted by Pilgrim View Post
    Is there a way to test the ignition switch before replacing it?
    The easiest way honestly is to visually look at it to see if it is separating. If there is a gap between the plastic and metal parts of the casing when turning the key, then it is most likely separating and causing the issues. It is a weird deal and does all kinds of sporadic goofy things when it is going out.

    If/when replacing, make sure you go back with a Motorcraft or high end switch as the McParts store cheapies do not get the job done for long. I just replaced mine on my 84 due to the same style issues.
    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?

  6. #6

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    Undo the 4 philips that screw into the column cover underside. Pull off the cover and tug on the wires. If they move at all, you have a fire hazard.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  7. #7
    FEP Super Member erratic50's Avatar
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    If it has sat for a long time the map sensor can just up and fail. It's the little black box with wires and a vacuum line on the firewall near the intake. I've had them test fine on the code scanner but turn up bad. If your 86 did this too, the bad map will cause it to make all the right noises but not start.

    +1 on ignition switch

  8. #8
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    OK, thanks for ALL the replies.
    Looks like the ignition switch needs a "security" torx?

    I finally did find the fuel schraeder valve, and hooked up my tester--no pressure. none, not a flicker. So where do i begin to look for power to the fuel pump? Isn't one of the fusible links near the battery for that circuit?
    I need a logical, step-by-step. I can't afford to simply replace parts--shotgun style. I need to be efficient in this repair.
    Remember, my goal is to sell it. Not that I want to leave a bunch of problems for someone else. But neither do i want to spend a couple of hundred$$ on parts that I may not need.

  9. #9

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    http://sbftech.com/index.php?topic=588.0

    I used some small vice grips on my fasteners. I had the earlier style bolts with a twist off head fastener.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  10. #10
    FEP Power Member Ourobos's Avatar
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    Key on, the ignition sends power to the ECU relay in the passenger kick panel, listen for it to click. That then sends signal to the fuel pump relay under the drive seat, listen for that to click, next to the inertia switch in the rear, check for 12v there.. Final piece of the puzzle is the pump if that is all good..
    1986 CHP SSP Coupe

  11. #11
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    Thanks, again--especially the link.

  12. #12

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    Yeah that link has gotten me and others home many many times. Joel is a good guy.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  13. #13
    FEP Super Member erratic50's Avatar
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    Security torx meet vise grip. Or cut down a straight blade bit until it just fits. There usually isn't very much torque there and they break loose.

    when you reinstall the screws with a new switch, medium hold locktight is a good idea.

  14. #14
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    OK, I THINK I got this figured out.......so please check me..

    I checked the fuel pump shut off relay ( in the trunk by the tail lights). I removed the 2 conductor wiring harness--red wire, red wire w/ black tracer--IIRC, red wire is 12V, red with tracer is switched 12 v, so i jumper 12 volts to the red wire w/ black tracer, and the fuel pump hummed. Still not showing any fuel pressure on the gauge at the schraeder valve behind the alternator even with the fuel pump running. I added another gallon of gas to the tank---just to be sure. Still no pressure--not even a hint or a fluctuation. Then I pulled the rubber air intake hose off the throttle body, and dribbled in a little gas, re-attached the air hose, and the car started! At this point, I see only 2 possibilities--either the pump is pumping and the fuel is leaking out somewhere, or the pump has failed. Since I see no evidence of fuel dripping under the car, it looks like i will have to drop the tank and replace the pump. I expect that if a filter somewhere had clogged, i would still see SOME pressure, but since there is NONE, I conclude the pump is fubar.
    At my age, dropping the tank on the ground is just too much, and since I have a lift ( just so i don't have to crawl around on the ground)....can I jumper the clutch switch and use the starter to drag the car onto the lift? Will that short time heavy load harm anything else?

    So what do you think...am I on the right track?

  15. #15
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    In looking at available pumps, I see complete assemblies and then just separate pumps ( at a MUCH lower cost). Can I simply replace the pump and re-use the rest of the existing assembly?

  16. #16
    FEP Power Member Ray Dog's Avatar
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    I haven't had a fuel pressure regulator go bad, but I have seen hydraulic pressure regulators
    Go bad and drag system pressure down.
    In other words pump maybe pumping but its all going back to the tank through a bad or stuck regulator?
    Ray
    86 Mustang LX 3.8 Convertible (bought new}
    65 Galaxie 500 XL 390 auto
    2A

  17. #17

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    Yes, replace just the pump. A kit with a lock ring new gaskets and a filter screen thingy is the way to go, but ignore parts stores. All crap for the most part. Get a walbro 155lph aftermarket for less then a stock pump.

    Also, buy a cheap fuel filter (you'll need it anyways after the pump probably) and the $12.99 fuel pressure tester at harbour freight. It reads plenty high and you can clamp a rubber hose to the filter. If its low to no preassure, swap in the new fuel filter just to rule that out.

    That way you can rule out everything except the short hose between the fuel pump and the filter.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  18. #18
    FEP Power Member Ourobos's Avatar
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    I would make sure the fuel filter is new, sometime they can clog.

    I had the same issue on an 86 SSP I just picked up.. Second time I had seen this.. There is a rubber 3/8" fuel hose that runs from the pump to the top of the pump bracket. Mine was rotted. I pulled the pump in anticipation of replacing it, but a piece of $2 fuel line solved it immediately. Since your pump is humming, it could likely be your problem as well.
    1986 CHP SSP Coupe

  19. #19
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    OK, and thanks again--I appreciate the experiences you all are sharing. Looks like i will be dropping the tank and replacing the pump, filter, and few little bits of hose.
    Much relieved--again thank you all for the guidance.

  20. #20
    FEP Power Member Ourobos's Avatar
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    Pump may be good if that hose is visibly rotted, will save you some cash
    1986 CHP SSP Coupe

  21. #21
    FEP Power Member BLK BRD 88's Avatar
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    If it was starting and running recently with no problems, I would do nothing until I had replaced the ignition switch with a motorcraft unit. These switches can cause some of the most "off the wall" problems imaginable.

    If it still doesn't start, then look at it as a possible fuel pump problem. The little hose on the pump that Ourobos mentioned has caused a bunch of us problems. Especially if the car has sat for a while with only a small amount of fuel in the tank it will rot and crack.
    Ron
    Last edited by BLK BRD 88; 06-11-2017 at 08:02 PM.
    I never seem to get the nut that holds the steering wheel fixed

  22. #22

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    He is bypassing relays, therefore the ignition switch
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  23. #23
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    I plan to get back on it Wednesday... even "semi-retired" old guys have to actually work a few days a week....and the heat is not kind to me. That should also break on Wednesday.
    I will keep you all posted on my progress and results.

  24. #24

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    Its 55º and raining here in utah, had a high of 64. The same jet stream is gonna carry right over ya.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  25. #25
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    Looking forward to that. It doesn't rain inside my garage!

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