Stalling when slowing

Discussion in 'Technical' started by Mlover, Jun 3, 2019.

  1. Mlover

    Mlover Member

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    Hey Maverick/Comet community. I'm back again with another headache right before an important weekend. My 1974 Maverick, with a 250 inline and automatic transmission, has been stalling on me on occasions.

    I first noticed it shortly after getting my exhaust fixed. I was taking it on a cruise and when I was nearly home (about a 20/30 min. drive) it stalled out on me when I slowed down to make a turn right before my house. It idled rough when I let go of the gas to cruise to the red light and it fully shut off when I pressed the gas when making the turn.

    The second time occurred on a different day. About 10 minutes after driving, I was in slow traffic and my car started idling a little rough. I tried to keep it going by pressing the gas very lightly when moving slow, but it stalled when I came to a complete stop.

    The last occasion happened about 10 minutes in the drive. Again I came to a stop, and it shut down when I fully stopped. Since then I have not driven the car.

    Some factors which I'd like to mention, not sure if they could factor in are:

    1. My carb choke plate seems to be stuck open. (Although I read this wouldn't affect it given that it is normally hot where I live California?)
    2. I have a small transmission leak


    I have the stock carb which if not mistaken is the Carter RBS. When I remove the air filter and press the gas I can see fuel going into the carb so I haven't replaced my fuel pump just yet.

    I'm not sure which tests to perform or how to perform them. Any advice?


    Thank you!!
     
  2. Hotrock

    Hotrock MCCI Member Supporting Member

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    Is all this stalling from the same tank of gas? Perhaps you have introduced water into your fuel system from contaminated fuel.

    Have you changed fuel filters along with any rubber fuel lines lately? Most likely stalling as you describe would be caused by a stoppage between the fuel pump and carburetor as opposed to issues between the tank and fuel pump.

    Even in southern California I would think your engine would also have a cold start stalling issue with the choke stuck in the open position. That should be easy enough to correct.

    Post several up close pictures of your carburetor, fuel lines and choke system.
     
  3. Acornridgeman

    Acornridgeman MCCI Wisconsin State Rep Moderator Supporting Member

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    4 out of 5 times this happens - low vacuum. Even a couple small leaks can do this. Check the timing too. A vacuum gauge is really useful here and can be used to diagnose many issues.
     
  4. Mlover

    Mlover Member

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    Thank you both for getting back to me.

    @Hotrock I have filled up once but the final stalling occurred again on a different tank of gas. The gas it currently has isn't more than a couple weeks old.

    In regards to the fuel filter, I don't think I currently have one. At least not one of those clear visible ones you see under the hood right before reaching the carb. Although, I think I will be adding one in the near future. I also have not messed with any lines or the carb (before stalling occurred).

    Cool. Would that require rebuilding the carb? The choke is stuck where you cannot wiggle it at all. Here are a few pictures I had available on my phone of the carb. I will post more from different angles, etc. today after work. I will also get pictures of the fuel lines and choke system.

    @ Acornridgeman I will invest in a vacuum gauge. Would the vacuum gauge identify the leak issue without having to do that propane leak test? Dumb question, how can I tell which line to connect the vacuum gauge to?

    In reference to the timing, do you know of a video tutorial / tutorial with images anywhere on how to check the timing on a car with specs identical or similar to mine? I've see videos on Youtube but most show how to check timing on more modern cars or different style engines. I thought I found an article but not sure it is referring to a 6inline ( https://itstillruns.com/time-ford-6cylinder-engine-7937809.html). It also has no images, so it is difficult to reference with my inexperience.

    Appreciate the help.
     

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  5. Acornridgeman

    Acornridgeman MCCI Wisconsin State Rep Moderator Supporting Member

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    I-6 just needs a timing light to check that, just like a V8. Most home mechanics have 1 or 2 of them, so just ask your car friends and maybe one of them can help you. Auto parts store might have a loner one too, depending on the store. As for a vacuum gauge, they are really handy to have for diagnosis and tune up, adjusting the carb, ect. They can tell you a lot about the internals of your engine like condition of the valve guides, rings, burned valves, improper timing - all sorts of things. Do an online search for "engine diagnosis with a vacuum gauge" - there are many youtube videos. The gauge goes to manifold vacuum. Lines get old and crack and even fall off on their own - so just because you didn't touch them doesn't mean they are OK.

    Good luck ……….. :thumbs2:
     
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  6. Hotrock

    Hotrock MCCI Member Supporting Member

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    I see you have a header on your in-line six and what appears to be a chrome valve cover.

    Your carburetor looks kind of crusty. Could use some carb cleaner. Also, I would think there is a fuel filter as part of the carburetor fuel inlet.

    You did not say whether your engine has a cold start issue? I have a feeling your choke may be adjusted to the full open position for some reason. I'm not all that familiar with what a stock Ford I6 choke wire looks like but that red wire on yours looks awful heavy duty. A simple choke adjustment may do the trick if you have a cold start issue. If cold start is not a problem, leave things as is unless you want to consider investing in a rebuilt carburetor.
     
  7. Krazy Comet

    Krazy Comet Tom

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    Lack of choke should not cause a stall problem on a warm engine(possibly cold).

    Incorrect timing could aggravate a idle issue but I doubt setting timing will be a complete cure. Possibly a idle mixture adjustment would help(adj for max vacuum) but probably it's time for a carb rebuild.
     
  8. Mlover

    Mlover Member

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    Thank you everyone for the input. A bit delayed, but attached are more images of the carb and lines. I can get more / better / different pictures if needed.

    Hoping to invest in a vacuum gauge and some carb. cleaner and get my hands dirty this weekend.

    The car has no issues on a cold start (although the weather TOO cold). But it starts up fine no issues. I will look into rebuilding the carb. I was going to either obtain a rebuild kit from Mike's Carburetor Parts or Summit racing does anyone recommend something different?
     

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  9. Acornridgeman

    Acornridgeman MCCI Wisconsin State Rep Moderator Supporting Member

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  10. Mlover

    Mlover Member

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    Thanks for the info!

    I went ahead and unplugged it from my carb and plugged up the ports. Hoping this might help? I would like to eventually remove it to get my engine cleaned up a bit. I will look into getting a plate to block it off. Do you know a part # for this?

    I ordered a vacuum gauge from amazon. Will update when I receive and test. For now I will also replace all my lines.
     
  11. Acornridgeman

    Acornridgeman MCCI Wisconsin State Rep Moderator Supporting Member

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    If it is stuck open, disconnecting it will not solve the problem
    When stuck open it allows exhaust back into the intake when you do not want it there.
    Cleaning them is a pain, as that carbon is very tough to remove.
     

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