help with 404 stalling with hard braking
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  1. #1
    Tadpole
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    Default help with 404 stalling with hard braking

    Hey guys,

    I am perplexed. Finally did a successful rebuild of the hydrovac on my 66 Peugeot Cabriolet (had a blown diaphragm). Brakes work great again, but when I'm driving and come to a stop light, holding my foot on the brake almost always causes the car to stall out. I always have my foot on the clutch (essentially keeping the car in neutral). At rest, if I leave the car in neutral, it always idles a bit unevenly, and putting my foot on the brake definitely slows down the engine and will sometimes stall it out. It always seems to stall when driving and suddenly stopping at a light, for example.

    This problem started about 5 months ago when the brakes stopped working well. I found the diaphragm in the hydrovac had ripped, and assumed this was causing excessive draw of vacuum causing the stalling. Now with a rebuilt hydrovac, the same problem exists except the car brakes well. I am guessing the problem is related to too much vacuum being sucked when the brakes are applied? I can't find any vacuum leaks, and even tried finding a replacement PVC valve. That seemed to help a little bit, making the idle smoother, but the car still stalls with hard braking in neutral. Any suggestions would be great.

    note: The engine was rebuilt last spring and the car was working great until the brake problems started in the fall. I don't want to risk rupturing another diaphragm, but don't think this problem caused that rupture. The car has a carb, which I replaced about 2 years ago. If I greatly increase the idle speed, it doesn't stall, but a resting idle of 2000 is rediculously high.

    Thanks- Paul

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  2. #2
    1000+ Posts Mike Tippett's Avatar
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    Sorry I couldn't help you with that one, Paul, so I will post this question at Le Club 404's forum and see what they say.
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  3. #3
    1000+ Posts Wildebeest's Avatar
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    Paul,
    The carburettor mixture adjustment may be set too rich to compensate for the vacuum leaks?
    This may also explain the need for the extreme idle speed?

    Cheers.
    John Wily.

    PS. A tip given to me. Always make sure the manifold to booster hose has an upward curve. This will prevent petrol vapour from entering the booster shortening the life of the booster diaphragm.

  4. #4
    1000+ Posts Mike Tippett's Avatar
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    The first reply at le Club 404 suggests temporarily disconnecting the booster vacuum coupleing and plugging both sides, the driving (slowly!!) in conditions to simulate the circumstances in which the problem is occurring now. If the car does not stall, the booster is defective (torn diaphragm)...... I know this seems impossible though, in your case.
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  5. #5
    Budding Architect ???? pugrambo's Avatar
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    Quote Originally Posted by Mike Tippett View Post
    The first reply at le Club 404 suggests temporarily disconnecting the booster vacuum coupleing and plugging both sides, the driving (slowly!!) in conditions to simulate the circumstances in which the problem is occurring now. If the car does not stall, the booster is defective (torn diaphragm)...... I know this seems impossible though, in your case.
    i'd go for setting the carb mixture and idle before heading down that path
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  6. #6
    Tadpole
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    Default Braking issue: Hydrovac hose

    Bendix recommends a check valve between the booster and carb to prevent any fumes reaching the booster. I bought one a few years ago from them and have it installed.

    I agree it seems to be a carb problem, and regret I discarded my old one which was very worn but functioning. It would have been nice to swap it out as a test.

    The only other symptom I neglected to mention (which probably has nothing to do with this), is the ammeter vibrates very finely. I saw in a different post about braking problems that someone speculated a poor ground wire could cause the ammeter to vibrate and at idle produce a very weak spark? I installed electronic ignition last year but that didn't fix the problem either. Any chance this is related to the stalling?

  7. #7
    Budding Architect ???? pugrambo's Avatar
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    Quote Originally Posted by redwood View Post
    Bendix recommends a check valve between the booster and carb to prevent any fumes reaching the booster. I bought one a few years ago from them and have it installed.

    I agree it seems to be a carb problem, and regret I discarded my old one which was very worn but functioning. It would have been nice to swap it out as a test.

    The only other symptom I neglected to mention (which probably has nothing to do with this), is the ammeter vibrates very finely. I saw in a different post about braking problems that someone speculated a poor ground wire could cause the ammeter to vibrate and at idle produce a very weak spark? I installed electronic ignition last year but that didn't fix the problem either. Any chance this is related to the stalling?
    give the car a tune up

    set the timing and then set the carb then go back and reset the timing again

    once you get the carb and timing right you shouldn't have any more dramas
    3 x '78 604 SL

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    1 x '99 406SV 5spd wagon, time to burn more fuel

    1 x 1994 605 SV3.0

  8. #8
    Tadpole
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    Default 404 brake and stalling

    I will try the complete tune-up: Timing, new wires and plugs. I recently installed electronic ignition. I agree the carb is a suspect and wonder if anyone knows if a Solex34BICSA/3 would fit. I think these cars have a Solex32, but I saw a 34 advertised as for a 404.

  9. #9
    1000+ Posts Mike Tippett's Avatar
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    Is your replacement carb from Argentina? The Club in France has condemned them because they are kind of crap.
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  10. #10
    Tadpole
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    Default Brake stalling and Carb

    Mike,

    Funny you should mention the lousy carbs from Argentina. I replaced the carb about 2 years ago with one from Argentina and I seem to recall now that it has never run that smoothly since the change. The old one was very worn and leaking a bit of gas so I discarded it.

    I see "new" solex carbs for sale from China. Do you think these are any better or do you have a source to recommend? Also, is it the 34BICSA that will fit correctly? As for the China ones, if you look at a site Alibaba.com they mass sell these carbs for about $40 if you buy a large quantity. This might say something about the quality?

    Thanks

  11. #11
    1000+ Posts Mike Tippett's Avatar
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    I doubt the Chinese ones are any better. I could ask the Club what the best option would be to get a new French one, or a good rebuilt one, if you like.
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  12. #12
    1000+ Posts Mike Tippett's Avatar
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    The Club indicated that the preferred way to deal with a worn butterfly (throttle plate) axle is to have it rebored and an oversized axle fitted, which in Europe costs about 70 Euros. With your original carb gone, you would need a core from a parts car etc, but this could well be the way to go. I am not sure how the Argentines made their cars run with those crappy carbs, or maybe they were not OE but are just aftermarket copies. I am thinking that there is a possibility that this (carburation) is the only problem that you still have.
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  13. #13
    Tadpole
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    Default Problem solved- Thanks to everyone

    Mike Tippett gets first prize for proper diagnosis! It was a faulty carb causing the car to stall with hard braking. I assume the carb didn't make enough vacuum to run the booster and engine? I was able to find my old original carb and rebuilt it (used to leak some gas). When I re-installed it, the car runs like a charm and doesn't come close to hesitating with hard braking.

    Lesson learned:

    1. Several in the forum suggested that the Argentinian carbs are not great. I think this is spot on. I bought this carb about 4 years ago from Argentina. It looks original and worked well for 2-3 years, but now this explains why the car hasn't run smoothly for at least a year. No idea what happens to these with use. I've only put on 1000-2000 miles with it.

    2. I also purchased a very inexpensive Solex from China (on Ebay) for about $70. I used it for a few days and it seemed to work fine, but looks cheap. The choke mechanism is greatly modified with this large metal plate and the accelerator cable needs to be about 3 inches longer to work. If you're desperate for a carb, I would probably so try the inexpensive Chinese one first, but you will have to extend the cable if you don't have much extra.

    Thanks to all.

    Paul

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