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  1. #1

    Default About to push car into a lake

    So I picked up a 82 mustang GT a few weeks ago. I am a guy that used to own camaros then spend a long time in srt4 and volkswagen world. Decided I wanted to get back into some muscle and has it not been so fun. Running a 5.0 with a 4barrel carb.

    Had issue other night where car was stumbling and I try to limp it home and she died and I pushed her home. Wife asked if I ran out of gas I said no way. Next day I bought 5 gallons just for hell of it threw it in and she fired right up. Drove fine for a few days then started to feel it sputter like it was missing. Went out and seemed like plugs 2,5,8 were not sparking ( wasnt noticable change in idle and plugs were dark). So went out got a new module, coil, cap, rotor, and plugs (already had ford performance wires last owner put on). Car fired up after install ran ok again for a day. This morning got up gave it no gas before cranking just turned key and about the loudest backfire I have ever heard. Then car just turned over but wouldnt fire. I was over it so I took a different vehicle to work.

    What you guys think I should look at or for. I going to check timing today if I can get ahold of a light. So used to newer cars with fuel injection and all the electronics. People say old cars are easy fuel spark compression. Sucks when you dont have something though cause then you have to look at everything not just scan see pxxxx and bingo. This whole carb and distributor world is a whole new game for me.

  2. #2

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    Hi JF,

    Don't push it into a lake, give it to me!

    Seriously, one easy thing to check is the wiring at the Duraspark module, if original. It should be mounted on the driver side fender apron just above the frame. The wires are exposed to heat and the insulation tends to cook dry and fall off. The car is 36 year old, you know. Make sure the wires are separated and insulated. My car would quit when I made a right hand turn. I wasn't a stumble then quit, just a quit. I may not be the problem but it is an easy fix.
    W

    As always, "It ain't what you don't know that gets you, it's what you think you know that just ain't so."

  3. #3
    FEP Member endub's Avatar
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    Check your wiring harness. If it has a bare spot in the wiring it will ground out and make it run crazy. I had it happen on my 85. I ended up getting a used harness from a member here and re loomed and taped it while it was off the car. Those old early 80s wiring harnesses will really rot if any oil or other corrosives come into contact with the plastic coating.

    Sent from my SAMSUNG-SM-G920A using Tapatalk

  4. #4
    FEP Power Member 4-barrel Mike's Avatar
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    Old coils can get wonky when they get warm. BTDTGTS*'

    Mike

    *Been There, Done That, Got The Shirt

  5. #5

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    Yeah I checked wiring at plug all looked good no broken insulation but maybe Ill ad some tape see what happens.

    I have been debating pulling harness and either cleaning it up or going with a new aftermarket one.

    Coil is new so that shouldnt be issue and the car wasnt warm.

  6. #6

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    I had a fairly new mechanical fuel pump go out on me a few weeks ago. Was a 1year old carter, I replaced it with a Delphi that is designed for use with blended fuels. Check the carb too, be sure the bowls are not too low or maybe even flooding with sticking floats. Also If the choke closes when the engine is hot it will die then later restart. I’m going fuel issue on this one.
    Last edited by Lowetlx; 06-20-2018 at 12:46 PM.
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  7. #7

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    Yeah see I have that feeling as well and no absolutely nothing about carbs. I was told it had a fairly new mechanical pump and it has a clear filter which was full so I do belive carbs is getting fuel. A tuning issue with carb or choke could definitely be a possibility. Last owner is a friend of mine and he races a foxbody and is coming by tomorrow to help me sort it out.

    One question I do have is. PS valve cover has a tube venting to air, and DS VC vent has one nipple going to carb and another nipple just open to air. Does that sound right>

  8. #8

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    what kind of carb and air filter set up is in this car? Holley or edelbrock. You should have a passenger rear valve cover breather running to back of the air filter housing. This draws in fresh air into crankcase. The driver side front should have a pcv valve with a vacuum line to the base of the carburetor. The second pcv valve port should be capped off. If it’s not you may have a large vacuum leak there.
    Last edited by Lowetlx; 06-20-2018 at 01:46 PM.
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  9. #9

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    Quote Originally Posted by Lowetlx View Post
    what kind of carb and air filter set up is in this car? Holley or edelbrock. You should have a passenger rear valve cover breather running to back of the air filter housing. This draws in fresh air into crankcase. The driver side front should have a pcv valve with a vacuum line to the base of the carburetor. The second pcv valve port should be capped off. If it’s not you may have a large vacuum leak there.
    I believe he said edelbrock but Ill confirm in a few when I get off work. Intake is Oem setup dual to fenders.

    Yeah PS is just a tube floating around maybe I pulled it off breather when I changed coil ill look for a spot for it to connect.

    DS pcv bottom goes to carb to does have huge leak I had finger on last night. Ill throw a cap on it tonight.


    Thanks a bunch for help. I am just so used to newer cars and all the electrical stuff and EFI. Been doing as much carb 101 on google as time permits.

  10. #10

  11. #11

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    Sold the black GTI beside it after I got the mustang. Total opposite 4cyl turbo 20psi vw to this carbed 5.0 lol

  12. #12

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    Looks like a great car, don’t give up on it, carbs are easy once you learn about them. I see the mirror coating fell off the back of the high beam headlamps. Grab some new headlights and it will look even better with out the grey lights.
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  13. #13

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    Quote Originally Posted by Lowetlx View Post
    Looks like a great car, don’t give up on it, carbs are easy once you learn about them. I see the mirror coating fell off the back of the high beam headlamps. Grab some new headlights and it will look even better with out the grey lights.
    LOL i didnt even think about that. I assumed they were just like that cause it matched. Once I get it running i going to fix the roof, clean up interior, suspension, rearend, then motor and tranny build. Nothing crazy just a fun street car

  14. #14

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    What kind of carb? If it is a holley, you will want to check the power valve if equipped after the backfire. They like to rupture and can cause several issues.

  15. #15

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    It's an Edelbrock 4 Barrell. Funny I got home cranked it twice and she fired right up. I tried messing with wiring on ignition module to see if I could make it better or worse but no change. I did plug that top vacuum line and she idles a little smoother. So I run the ps to the air breather? Pics below are how it is.

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  16. #16

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    Doesn't seem like ps one has any vacuum though like other side

  17. #17

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    The Passenger side should not have vacuum. It should clip into the back of the air cleaner. in your pic do you see the orange/ brown kidney shaped thing in the air cleaner pan? It clips into that. Where it sticks out the back of the air cleaner. That’s the breather. There should be a filter element in that orange holder also to keep the engine clean. The system takes in fresh air there where it is then sucked into the engine by the pcv valve on the other side.
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  18. #18

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    Quote Originally Posted by Lowetlx View Post
    The Passenger side should not have vacuum. It should clip into the back of the air cleaner. in your pic do you see the orange/ brown kidney shaped thing in the air cleaner pan? It clips into that. Where it sticks out the back of the air cleaner. That’s the breather. There should be a filter element in that orange holder also to keep the engine clean. The system takes in fresh air there where it is then sucked into the engine by the pcv valve on the other side.
    Thanks a lot. Yeah i must have knocked it off when i moved for coil. No element in air cleaner though. I guess if start up keeps being an issue ill look for an engine harness.

  19. #19
    FEP Senior Member
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    Don't forget to check for a broken ignition switch, of a bad fuel filter or rubber line.

  20. #20

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    Quote Originally Posted by teddy1500 View Post
    Don't forget to check for a broken ignition switch, of a bad fuel filter or rubber line.
    Yeah fuel filter is clear and visually looks clean but I may get another anyways. How would I troubleshoot if it were ignition switch. Everything seems to act normal other than no run. Am I right thinking to test for 12v on coil?

  21. #21

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    Ignition switch causes all kinds of strange running problems. Plastic and cast base will separate over time. They are available everywhere. This is what it looks like. It mounted on the column connected the the actual key switch by a rod.

    https://lmr.com/item/LRS-11572A/79-9...RoCwtoQAvD_BwE

  22. #22
    FEP Senior Member Matt J's Avatar
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    Everyone is giving you good advice about things that can definitely go wrong with your car, and with 30 year old parts, it's likely that you'll be replacing a lot of things over time while you maintain the car. My advice is to keep things simple before you start cutting up wires and digging deep into the mechanicals. From what you say, it seems like the car runs very well sometimes, then after using it for a time, something changes and it doesn't run well. It's entirely possible that you have problems with your wires or other things, but if it runs well sometimes, and you can't see any obvious damage to the wiring harness, then it's probably not as likely as other possibilities. This particular engine has things that adjust and change as it heats up, goes under load, switches the AC on, lots of things. Your timing can adjust too, which is one of those things that can change as you use the car. Many of them are controlled by vacuum lines, which undoubtedly have some cracks and leaks in them. Vacuum leaks will wreak havoc on things running well. There are other parts of the carb controls like the dashpot and the choke heater (pull-off), if they exist on the one you have, that have vacuum controls and bladders in them. If vacuum is ported to one to do something, it will create a leak and the motor will run like complete junk.

    It's good that you have a friend who knows the car and something about carbs that is going to help you out. That is your most likely culprit, unless you truly do have a spark issue. I assume you didn't actually test the spark to those cylinders you say sounded like they were dead, because pretty clearly if they were not getting spark, well there's your problem. It sounds more like fuel and vacuum related if it's not something due to timing or spark. If it starts and idles well, and even runs well for a time then starts to run poorly or quits, look for those things that would change as the engine goes from one operating mode (such as cold idle, cruising RPM, under load, wide open throttle (WOT), etc) and what controls them. Can be too much or not enough fuel, or maybe the timing is off. I think when you get a backfire it's usually timing and/or fuel.

    Anyway, start with the easy stuff first before you start pulling switches and wires. It's old, more than likely you're going to find that it needs a little bit of everything!

  23. #23

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    I checked voltage on coil today and when going from coil + to - I had between 3-4v from coil + to battery ground i had 11. Does that sound right. Wondering if that is my issue. I did have it running and had same voltages

  24. #24

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    Whenever I buy a used car, I replace EVERYTHING. All wires, hoses, PCV, coolant... you name it. I replace anything that can be brittle or need replacing to rule everything else out. I always change the fuel filter and run fuel cleaner periodically. I baby all my cars and they all run perfect. I am a huge stickler for maintenance. That is a super nice car and is worth spending the money on everything under the hood to make it road worthy.

  25. #25

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    If you've had a 30 year-old car for 2 weeks and are already wanting to push it in a lake, I would suggest putting that baby right back up on Craigslist. Old cars are a LOT of work to keep running. The newer cars are more reliable just as you suggested for very obvious reasons. They are newer. When a Toyota Prius (where you can just plug a code reader in it and a get a Pxxx and BINGO) turns 30, let's just see how much fun they are to daily drive. IF any of them are even running at 30 years old.
    That being said, that is a nice looking car. I see why you bought it. You are on the right path. Get the timing sorted and vacuum leaks all fixed and see where you are. And those Ford "performance" wires are Chinese garbage. But if you don't have a miss then they likely are okay for now. And as 4-barrel Mike said, I don't even trust an old coil that tests good if I'm having bizarre issues. It seems they "pass" one day and totally "fail" other days. As Mike said, temperature TOTALLY affects old coils too it seems like.
    Last edited by homer302; 07-05-2018 at 06:31 PM.

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