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vapor lock on a modified 53 coupe

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  • vapor lock on a modified 53 coupe

    Help!! Could it be possible that I am having a vapor lock problem with my 1953 c coupe? I am aware of the vapor lock problems inherent on 1953 studebakers as I had one while serving in the army in Kentucky in 1958 but never thought I would have that problem since I have modofied the car with a big block chev engine a 700r4 trans and a 9 inch ford rear and also used a phantom front end suspension package from slik street stuff. The only part of the original fuel system I am using is the gas tank. I have a holley blue electric fuel pump mounted in the rear near the tank and ran the fuel lines along the passenger side frame rail to a fuel regulator which maintains 7 pounds of pressure to a holley 750 carb. The exhaust system is dual and all new. I can start the car without any problems but when I drive 20 or 30 miles and shut it off it won't start until I let is set for 30 or so minutes and use jumper cables
    Any help would be appreciated.Thank you Joe Dipipi...joedipipi@msn.com

  • #2
    Try loosening the gas cap and take it for a drive.
    If a more modern gas cap was added, most of them are NOT vented, because the venting is done elsewhere.
    It doesn't take much of a vacuum to stop fuel flow, even with an extra pump.
    Worth a shot anyways...and it is a free test.
    Jeff
    HTIH (Hope The Info Helps)

    Jeff


    Get your facts first, and then you can distort them as much as you please. Mark Twain



    Note: SDC# 070190 (and earlier...)

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    • #3
      Question...
      When you say you cannot start it 30 minutes later...
      Does it crank?
      Does it crank fast?
      Your mention of jumper cables being needed points my feeble mind to a common GM starter issue....
      Heat soak.
      A lot of GM starters (solenoids) have a heat soak vulnerability when it gets real hot out.
      Adding a separate 'hot start' relay really does help in this situation.

      Google GM hot start relay.... Lot's of hits.
      I like this one (for obvious CASO reasons)
      http://www.oldengine.org/unfaq/solenoid.htm
      HTIH
      Jeff[8D]
      HTIH (Hope The Info Helps)

      Jeff


      Get your facts first, and then you can distort them as much as you please. Mark Twain



      Note: SDC# 070190 (and earlier...)

      Comment


      • #4
        yes it does crank over fast the use of the jumper cables probably wasn't needed just happened to have them with me the 2nd time it happened to me. the 1st time it happened I was driving the car and it acted like it was flooded and shut me down.
        That time I didn't have jumper cables with me and about a 1/2 hour later after several attempts to start it it started. Thanks for the help as soon as my grand daughters wedding is over this weekend I'll go for a ride and try to sort it out a little further. again thanks for the info.

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        • #5
          While i was doing the movie, the Conestoga vapor locked, I hand choked it till i got it running and had to keep chokeing it till cooler gas was flowing thru the fuel pump and/or carb to keep it running, once it picked up cooler fuel it ran ok. Going to ad an electric fuel pump and maybe even a mopar mechanical pump to try to cure this once and for all. extra carb gaskets will also help.

          101st Airborne Div. 326 Engineers Ft Campbell Ky.

          Comment


          • #6
            I agree with Jeff.
            Sounds more like "starting" problem than a fuel problem.

            1. Too light duty a battery
            2. Too old a battery (won't hold a charge)
            3. Bad connections (most anywhere in the starting and charging system)
            4. Long battery cables (battery in the trunk ?)
            5. Too small a diameter of the battery cable (battery in the trunk ?)
            6. Battery not grounded well (should have more than one, or straight to the starter)

            Could be any one of or a combination of the above.

            That gas cap DOES need to be vented ! I just drilled a small hole in the valve in mine...works fine now.

            Good luck.

            Mike

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            • #7
              I plan on working on the possibility that it may be the battery since it is and old battery but it always seems to turn the motor over and crank very good. grounds are all good, connections are all good, correct battrey cables were used will try removing the gas cap. Since this car is so modified i feel that you fellows are right and it could be another problem and a good chance its the battery. Thanks for the posts and I'll let you know the results..Joe Dipipi..... joedipipi@msn.com

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              • #8
                Make sure you have good connections on the ground between the body and engine. Make sure you don't have a bad freeze plug leaking water on the solenoid. And if you have carbon buildup causing preignition, you could try pumping the gas a few times before cranking it to cool down the carbon deposits.

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                • #9
                  I could be wrong, but if the fuel cap was creating a problem I think it would happen when the car was running, not only when the car is shut down. If the engine cranks over at a decent rpm then I think the battery, and associated components can be eliminated. The times I have experienced a starting system (starter, relay, etc) electrical heat soak issue, the cranking over of the engine slows down due to the added resistance caused by the excess heat; it acts like a poorly performing battery. Is this a new problem? One more thing to consider is electronic ignition modules(if you have one) , and coils, heat can affect the performance of these components.

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