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Thread: Hesitation or chugging when getting on gas

  1. #1
    Join Date
    Aug 2009
    Location
    Logan, Iowa
    Posts
    2

    Default Hesitation or chugging when getting on gas

    I have a 1976 Scout 2 with a 345. Since I have owned it, (about 3 years) it has always hesitated or chugged for a moment when i touch the gas but only when I am in drive. In neutral or park I don't have the problem. I have been told it is not a big deal especially since it is most noticeable only when moving from a stop. On the highway it doesn't occur as much. If i get on it a bit say going from a stop sign, it will hesitate for a second or two and then take off, it has really began to get on my nerves. I am not extremely mechanicly inclined so I am unsure of the problem. I am guessing the problem is in the carb. I put a carb kit on it when i bought it and drive it pretty frequently so i am confused on what it could be. A mechanic buddy has told me i should use the highest octane gas but this has not made a huge difference. Any help or suggestions would be great. Thanks

  2. #2
    Join Date
    Jun 2009
    Location
    Hurlburt Field, FL
    Posts
    495

    Default

    Start with the simple stuff. Fuel pump, fuel filter, good plugs and wires, good cap and rotor, you get the picture. Then check your mixture in the carb. It's quite possible that you're dumping too much of one (fuel or air) in and not enough of the other to compliment it, so it takes a second or two to catch up with itself.

  3. #3
    Join Date
    Jul 2009
    Location
    Jacksonville, FL
    Posts
    18

    Default

    The carburator would be my first suspicion as well.

    When you step on the gas, a lot of things have to happen to get a correct increase in the amount of fuel and a correct increase in the amount of air. If any part of carb is leaking air or fuel, clogged, or misadjusted, it may still run fine under steady load but fail when you step on the accelerator.

    What exactly was your carb kit? Believe it or not, these can acutally cause problems like what you are describing. "Bigger jets" or "smoother airflow" all sound like good things, but a carburator is all about balance. Sometimes these kits are designed with a particular goal in mind, like MORE POWER!!!!, but they do it at the expense of a properly balanced fuel/air flow under normal driving conditions.

    Also, Drive is different than Neutral or Park because there is only a small load on the engine in N/P.

    If there are tuning instructions that came with your carb kit, I would start there. If not, I would look at the factory carb tuning instructions. I can post the service manual instructions if you need.

    To test for air leaks, you can open the hood with the engine idling. Spray a few puffs of aerosol starter fluid at various gaskets and hoses of the carburator. If it is pulling air where it shouldn't be, it will kick up the idle RPM for a second.

    I don't know of any good tricks to test for fuel leaks internal to the carb, but you should definitely follow lindstromjd's advice to check fuel and ignition systems.

  4. #4
    Join Date
    Jun 2009
    Location
    Little Rock
    Posts
    40

    Default

    What carb is on your scout?

    I had the same problems with my 73, it had a motorcraft carb. I did everything you could think of to fix it...except replace the carb. When I threw a brand new holley 2 barrel on it that pretty much fixed all the problems I had.
    Again, do start with the easiest, most obvious should be first on the list. I would definatly rule out all other problems before buyin something your not definatly sure will fix it.

  5. #5
    Join Date
    Aug 2009
    Location
    Logan, Iowa
    Posts
    2

    Default

    Thanks for all the advice, it has been awhile since the carb kit was put on and I do not know what kind it is or the specifications for it. The carburetor is a holley 2 barrel and i am really not sure if the mixture is set correctly. The factory carb tuning instructions would be helpful. This sounds like it could be the problem because the feul pump, filter, plugs wires and the cap and rotor have been replaced since I have owned. If you could post the service manual instructions for the carb it would be great. Thanks again for all the help.

  6. #6
    Join Date
    Aug 2009
    Posts
    23

    Default

    To me it sounds like the accelerator pump. That is if it is the same exact rpm that flutters every time at take off and it never happens before or after. Just a splutter that kicks in every single time. If that sounds like what is happening, it has been years but I believe you replace a diaphragm.

    They give a quick squirt of gas when taking off. Most of the time there is a small hole in the diaphragm and you can get by with just that. Sometimes you have to replace the whole accelerator pump. You can try a little dab of rtv sealant on the diaphragm for trouble shooting.

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