68 Coupe hard to start when hot
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RWD 19xx-1984 DeVille and Fleetwood,
1985-1996 Fleetwood and Brougham Forum Discussion, 68 Coupe hard to start when hot in Past Cadillac Vehicle Discussion; My 68 Coupe starts right up in the morning and after it cools some after driving it. But when I ...
  1. #1
    sober2day is offline Cadillac Owners Member
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    68 Coupe hard to start when hot

    My 68 Coupe starts right up in the morning and after it cools some after driving it. But when I drive 10+ mins and turn it off, come out, it slowly turns over like the battery is dead. I'll turn it a couple times and most times it will barely start. Other times it will start with a quick jump. The battery terminals will get hot during this. I know the wires on the starter need replacing. Could this be it or what could be causeing this? HELP!!

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    SafariOne is offline Cadillac Owners Fanatic
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    Re: 68 Coupe hard to start when hot

    Some possible causes of hard starting could be starter on the way out, fuel pressure regulator malfunctioning, you could try and retard the timing a couple degrees and see if that makes a difference. Sometimes a weak fuel pump will act like that as well. Good luck....

  4. #3
    csbuckn is offline Cadillac Owners Master
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    Sounds like heat sink in the starting circuit.

  5. #4
    carnut is offline Cadillac Owners Master
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    Re: 68 Coupe hard to start when hot

    Anything in the starting circuit that is loose, corroded or missing can cause this. Everything from the battery terminals to the starter connections must be clean and tight. There should be a ground wire from the engine to the frame or at least to the firewall as well. Timing too far advanced can cause this as well. Fix your starter connections 1st.

  6. #5
    Angry Matt's Avatar
    Angry Matt is offline Cadillac Owners Enthusiast
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    Re: 68 Coupe hard to start when hot

    I fought with the same issue on my '70 for over a year, replaced everything that everyone told me to replace (not that it didn't need it) and adjusted everything. Turned out it was the battery. When you go to get your new wires have them test it, most places will do it for free. Just saying, before you make yourself crazy like I did, start simple.

  7. #6
    SafariOne is offline Cadillac Owners Fanatic
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    Re: 68 Coupe hard to start when hot

    Good point AM......

  8. #7
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    erichthecatt is offline Cadillac Owners Fanatic
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    Re: 68 Coupe hard to start when hot

    I had this same problem on my 70 Eldorado. The shop where I always had my generators, alternators, starters rebuilt suggested that I install an additional starter relay (external ford type), and that would cure my problem. I just dont remember how he told me to wire it.

  9. #8
    j2rossit is offline Cadillac Owners Enthusiast
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    Re: 68 Coupe hard to start when hot

    This sounds like one of the common problems of this generation GMs (I had this on my 68 Wildcat). The starter solenoid gets stuck when the windings swell due to the heat. A new starter will have a better lubricated solenoid. As ericthecatt said, you can wire in a relay to give more power to the windings to help move the solenoid. It's a cheaper fix than buying a new starter. I've attach a pic of the fix.
    Attached Images

  10. #9
    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
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    Re: 68 Coupe hard to start when hot

    Try cheap stuff first. Make sure mechanical advance in distributor is not binding causing timing to be too far advanced.

    A good shop will be able to test your starter current draw and battery capability along with voltage drop to starter under load.

    Older Rottenchester carbonators leak gas from the fuel well when the lead plugs go west. This causes vapor lock. Well known problem.

    Good luck.

  11. #10
    SafariOne is offline Cadillac Owners Fanatic
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    Re: 68 Coupe hard to start when hot

    Had a hard start problem with my 81 with 368 c.i. when hot and I replaced the stock fuel pump with a Turbo pump and end of problem. Vapour lock of course.

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