Help 85 Mustang Cranks, Won't Start

Discussion in 'Fox 5.0 Mustang Tech' started by jake anderson, Sep 15, 2013.


  1. jake anderson

    jake anderson New Member

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    Got an 85 mustang gt, the wiring in it was really messy and all over the place because it's had lots of owners and the guy I bought it off was going to turn it into a drag car, it wouldn't start a couple days after i got it and i got it checked by my mechanic. He put a new electric fuel pump in it and started it up fine, i went for a drive and took it home and the next day it wouldn't start. I've tried gas and starting spray in the carb and it won't start. When i turn the key the engine cranks but it refuses to start
     
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  2. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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  3. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    you may need to talk to a carb guru though, as lots of that list is directed at efi cars
     
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  4. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    There is a version for carb cars, but it's not as comprehensive...

    Cranks Ok but no start for carb’d cars.

    Updated 17-Jun-2008 to include firing order diagram

    Carb'd cars require an old time approach to troubleshooting.

    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 with the red wire 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.) Coil
    B.) Distributor PIP sensor or points & condenser
    C.) Bad ignition Box or Duraspark unit
    D.) No power to ignition system wiring or ignition box (if used)
    E.) Bad ignition switch
    F.) Bad fuse links.


    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.
    4.) Pull the air cleaner and sniff for fuel vapor - look for signs of flooding. If so, then press the accelerator to the floor and crank for a while – if the engine is flooded, this will clear it out. You may want to have a jumper battery & cables handy.
    5.) Electric fuel pump if you have one, is it getting power? Use a volt meter or test light to probe the wires at the pump.

    Don't see any evidence of flooding? Then pump the throttle - does the accelerator pump squirt fuel? If so then you should have enough fuel to start the engine. If not look for fuel delivery problems. Check the fuel pump, and fuel filter. Remember that most carbs have a fuel inlet filter that protects the float needle valve from trash.

    Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air cleaner, open the throttle, and spray the ether in it. Reinstall the air cleaner and try to start the car. Do not try to start the car without reinstalling the air cleaner. If it backfires, the chance for a serious fire is increased. If the engine starts now, you have a fuel delivery problem.

    A warning about backfires: Holley carbs may have damaged power valves as the result of a backfire. The engine may be hard to start. Other symptoms are that it may seem to load up on fuel and be slow to accelerate until it clears out a bit.

    6.) Fuel & ignition OK:
    The HO firing order is 1-3-7-2-6-5-4-8.
    Non HO firing order is 1-5-4-2-6-3-7-8

    [​IMG]

    Check to verify that it is indeed an HO engine. Remove the #1 & #3 spark plugs. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Slowly turn the engine until the TDC mark and the timing pointer line up. Mark TDC on the balancer with chalk or paint. Put your finger in #3 spark plug hole and crank the engine 90 degrees. You should feel pressure trying to blow past your finger. If you do not feel pressure, repeat the process again. If you feel pressure, it is a HO engine.

    No pressure the second time, remove spark plug #5. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Put your finger in #5 spark plug hole and crank the engine 90 degrees. If you feel pressure now, the engine is not a HO model, no matter what it says on the engine.

    Using a small carpenter or machinist square to mark the harmonic balancer off into 90 degree sections may be helpful here.

    A 15/16 deep socket & breaker bar or ratchet may be used to turn the engine.
     
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