DS21 Starting problem
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Thread: DS21 Starting problem

  1. #1
    Tadpole
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    Default DS21 Starting problem

    I would appreciate some help diagnosing a starting problem with my 68 DS21.
    IF she sits for more than 2 days without being used she won't start . Turns over fine . However if I remove the air filter hose from the carby and put my hand over the carby then she will kick over and start. Then no problem starting again unless left for a few days or more.

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    Thanks in anticipation.

  2. #2
    Fellow Frogger! JAJEA's Avatar
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    Quote Originally Posted by pale View Post
    I would appreciate some help diagnosing a starting problem with my 68 DS21.
    IF she sits for more than 2 days without being used she won't start . Turns over fine . However if I remove the air filter hose from the carby and put my hand over the carby then she will kick over and start. Then no problem starting again unless left for a few days or more.

    Thanks in anticipation.
    When you "choke" an engine you get a rich air fuel mixture to the combustion chambers and hence the firing and subsequent running.
    Check the choke mechanism (no idea what the Ds21 has), is it manual or automatic? .
    And make sure that you have no leaks in the carburetor. Some require a pump on the accelerator to squirt a dose of that rich fuel
    /Air mixture for starting purposes, the process of choking accelerates fuel getting into the carburetor.
    John

  3. #3
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by pale View Post
    I would appreciate some help diagnosing a starting problem with my 68 DS21.
    IF she sits for more than 2 days without being used she won't start . Turns over fine . However if I remove the air filter hose from the carby and put my hand over the carby then she will kick over and start. Then no problem starting again unless left for a few days or more.

    Thanks in anticipation.
    Have you tried pulling the choke out ................................................
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    The first thing for me that comes to mind is to check the fuel pump. It may have diaphragm leaking internally.

    Maybe an original replacement or an electric one may be the answer. The electric type although not original is better as they supply fuel to the carby quickly and saves wear on the starter-motor and they start much quicker. They can be fitted discreetly leaving the original one in place.

  5. #5
    Fellow Frogger! ds21bvh's Avatar
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    Pale,
    When you say won't start - do you mean after about 5 seconds of cranking?
    My DS21 after sitting for weeks sometimes takes 30 seconds of cranking to bring the fuel back up.
    This happening after a couple of days tells me there is probably a joint in the carby line which is not sealing properly, that or as DS/ID says a fuel pump valve or diaphram.
    Kind regards,
    Mark

    John - manual choke on a DS21.

    BTW guys - can we sign off with our names? Just like to know who I'm talking to.

  6. #6
    Fellow Frogger! JAJEA's Avatar
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    Quote Originally Posted by DS/ID View Post
    The first thing for me that comes to mind is to check the fuel pump. It may have diaphragm leaking internally.

    Maybe an original replacement or an electric one may be the answer. The electric type although not original is better as they supply fuel to the carby quickly and saves wear on the starter-motor and they start much quicker. They can be fitted discreetly leaving the original one in place.

    Agreed however beware, electric fuel pumps generally "pump" at higher pressures than the mechanical ones attached to the car's engine and may thus require a pressure regular to match the original. There is a limit to what the carburetors float valve can hold back.

    John

  7. #7
    Tadpole
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    Mark,
    Put a one-way valve between fuel filter and pump inlet. It'll prevent fuel from going back to tank. I put it on all cars with mechanical fuel pumps.
    Or go electric, fantastic solution.

    pale,
    Check the choke cable. Is it fastned nicely on the carb (m4 on the cable and m5 on the outer sleeve), does the flap close when you pull on the choke from cabin?

    Sent from my FRD-L09 using aussiefrogs mobile app
    DS/ID likes this.

  8. #8
    Tadpole
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    JAJEA,
    I have one from Land Rover that is for carb use. Diaphragm, built in filter, stops pumping fuel when pressure rises. And, it's quite quiet.

    Sent from my FRD-L09 using aussiefrogs mobile app

  9. #9
    Tadpole
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    Choke engaged and working. Cranked more than five times and sufficiently.
    I suspected fuel pump, checked it after the filter and it pumps when cranking.
    Thanks Terry

  10. #10
    Fellow Frogger! ds21bvh's Avatar
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    Quote Originally Posted by Zlexa View Post
    Mark,
    Put a one-way valve between fuel filter and pump inlet. It'll prevent fuel from going back to tank. I put it on all cars with mechanical fuel pumps.
    Or go electric, fantastic solution.

    pale,
    Check the choke cable. Is it fastned nicely on the carb (m4 on the cable and m5 on the outer sleeve), does the flap close when you pull on the choke from cabin?

    Sent from my FRD-L09 using aussiefrogs mobile app
    Hi Zlexa,
    Is there a specific brand of one way valve you use? A link or two would be wonderful.
    Cheers,
    Mark

  11. #11
    Tadpole
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    Quote Originally Posted by pale View Post
    Choke engaged and working. Cranked more than five times and sufficiently.
    I suspected fuel pump, checked it after the filter and it pumps when cranking.
    Thanks Terry
    So, fuel is ok, choke is ok, but fails to start...
    But she works fine afterwards? No breaking up or rough revving after warming up?
    I doubt that carb is clogged, since you have filter, and there isn't much that can go wrong with it, except wear over time. The shaft can become too loose so it's draws extra air.
    Maybe, just maybe, distributor might need some tuning. Or condensator is failing, or contact breakers are out of tune (0.4-0.45 mm).
    I'm throwing some ideas, but I do it that way as well, go around and cross stuff that is ok and working.

    Sent from my FRD-L09 using aussiefrogs mobile app

  12. #12
    Tadpole
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    Quote Originally Posted by ds21bvh View Post
    Hi Zlexa,
    Is there a specific brand of one way valve you use? A link or two would be wonderful.
    Cheers,
    Mark
    The one I have on my daily, Fuego, is a aluminium alloy one from aliexpress, been there for a year at least. No problems with it. A friend of ours has one of these (same looking, just bought in a store), for at least 4 years without problems. We had to clean it because of messy tank, but it still works.

    https://s.click.aliexpress.com/e/3H1LfDR6
    One of these. It can be taken apart and cleaned, checked...
    You could check automotive stores, they should have them.



    Sent from my FRD-L09 using aussiefrogs mobile app

  13. #13
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    Choking or putting hand over the carburettor is sucking the fuel via the compression of the engine and helping the pump get fuel to the carburettor. I believe when this has been achieved the pump is able to supply fuel probably at a lesser rate than it should. The fact it starts ok if run regularly indicates to me that the fuel is still in the line long enough to allow those starts.

    Left for a period of two days or more seems probable the fuel has drained back down the line and the pump cannot on its own bring the fuel back to the carburettor.

    To test this, leave the car not started for two days or more and before trying to start undo the fuel fitting to the carburettor and see if by turning over as if to start the fuel does get to the carburettor. If it does then it’s not the pump and look elsewhere.

    Doing this test should be done with the help of someone else and you must be careful.

    My bet is that this is what may be the problem and a new pump is the answer. A one way valve is also an excellent idea.

    Cheers and good luck

    Andrew

  14. #14
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    I fitted a facet electric fuel pump in the fuel line on my Alfa. I fitted a a press button switch mounted under the dash and this only operates before startng after a few days /weeks . It brings fuel up then the mechanical pump continues as per normal. A non return valve is a good idea - very cheap. I fitted one to my traction
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