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Thread: 1986 Cougar 3.8 L won't idle.

  1. #1
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    Question 1986 Cougar 3.8 L won't idle.

    My 1986 Cougar 3.8 L V6 won't idle on its own. The milage is 135,000, which is relatively low for the age. If I manually spray starter fluid down into the throttle body the car starts right up and runs great until the fuel is burned off. I have replaced or done the following:
    1. replaced the fuel pressure regulator
    2. replaced the fuel injectors
    3. replaced the control module
    4. replaced the pick up coil
    5. replaced the fuel filter
    6. replaced the computer
    7. replaced the battery cables
    8. fuel pump is ok and fuel pressure is good
    9. Bought a tune up kit for the throttle body and did that

    After doing all of this there is no change and the car will not idle on its own. ANY ideas on how to get this car running again???

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    Still waiting on what codes are being thrown...

    http://www.foxtbirdcougarforums.com/...idling-problem

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    Yes, same car - and very frustrating. And now it's over at a car repair shop and they say it's not showing any codes. Maybe this could be because the battery was disconnected over the winter therefore all codes would have been lost? Also, since they put a new computer in it would it show codes without being driven? The car hasn't been driven any distance since the "it won't idle" problem started last summer. The mechanic said the only thing they can think of doing is to replace the throttle body…this doesn't make sense to me since the throttle body has already been rebuilt/cleaned when I installed the new injectors. What do you think?

    Also, I never did pull a spark plug to see if they could be the problem. Could new plugs solve this? I am lost…

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    Did they actually check the codes or just look to see if the check engine light was on? These cars can still have fault codes with the check engine light off.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
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    Quote Originally Posted by thunderjet302 View Post
    Did they actually check the codes or just look to see if the check engine light was on? These cars can still have fault codes with the check engine light off.
    The check engine light hasn't worked in the car for years. The mechanic I had the car towed to has the diagnostic equipment to check for codes even if the light isn't working or so I am told. He said it was throwing no codes. Besides, wouldn't the car need to be driven for a certain amount of time (miles) before it would show codes after the battery was disconnected for months (during the this past winter)?

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    Won't run or won't idle?

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    Quote Originally Posted by softtouch View Post
    Won't run or won't idle?
    If I spray starter fluid (or pour in gasoline) directly into the throttle body the car runs great until it burns the fuel off. Also, I replaced the throttle body sensor (TPS) as well but it hasn't made any difference. Any ideas?

  8. #8
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    Well it sounds like a fuel delivery problem.
    You said (maybe in your other thread) that you had good fuel pressure.
    Was this checked at the Schrader valve test point in the CFI (throttle body)?
    If you have pressure at the fuel filter and not at the CFI, check for a crushed fuel line between the two.

    If you have pressure at the CFI, check if the injectors are spraying fuel while cranking. Look, smell. dangle something in there to see if it gets gas on it.

    If the injectors are spraying you may have a vacuum leak that is making the fuel/air mixture too lean to run.

    "Good" fuel pressure is 39 psi.
    Last edited by softtouch; 04-21-2018 at 12:52 PM. Reason: add fuel pressure

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    Parts artillery, Ready, Aim, FIRE!
    or
    You could try testing. You've got lots of really technical guys here, who understand the product deeply and have very valuable insights and advice.
    You were asked if it doesn't run, or runs but doesn't idle. Translation: If you DON'T give it alternative fuel, will it start and remain running with throttle applied?
    This is a critical distinction, because if it runs with your foot on the gas, you could have one set of problems (such as a failed idle speed control motor or a large vacuum leak), but if it doesn't run at all, you could have a DIFFERENT set of problems (like no injector pulse, poor fuel volume, a failed MAP sensor, etc).
    1988 Thunderbird 5.0
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    Thanks to all trying to help me with my Cougar. I am not a mechanic so please forgive my ignorance. To be clear, it will not start with the throttle applied. It will only start if fuel is manually sprayed or poured directly into the TBI.

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