only runs with full choke

Discussion in '1947-1954' started by dan cocomise, Mar 16, 2012.

  1. dan cocomise

    dan cocomise Member

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    235 will only run with choke close,but with gas tank half full runs much better than full tank. but still fully choked.I checked for vacume leaks carb manifold vacume lines none.new filters gaslines tank gas cap is vented.cold it be my fule pump,pump is rather new or vacume advance.thanks
     
  2. Lakeroadster

    Lakeroadster Member

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    Might be an intake leak. Spray some carb. cleaner around the intake manifold and the base of the carb. and listen to see if the engine rpm's increase. If they do you have located the problem.
     
  3. Blueflame236

    Blueflame236 Member

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    Thinking of the same here but check fore condence aswell

    Water condence in the fuel acts like that and a carb that needs to be looked over fore particals. Halv tank of fuel could mean you have a vacume problem related to the dust in your tank or your gas tank filter is greasy ?. Full tank makes the vacume (gas concentration ) go out at the neck .Ad some Isopropanol fluid to your fuel once in a while , wait 15 minuttes and se what happens ! It brings the water particles down to the bottem and you can empty it out at springtime.

     
    Last edited: Mar 17, 2012
  4. dan cocomise

    dan cocomise Member

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    i have a new tank new sender new lines new fillter .whith the old tank i hade 2 filters to carb.i opend bowl it looked clean.i will clean carb jets i know someone who has cleaning tank .thanks
     
  5. coilover

    coilover Member

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    First, eliminate fuel as the problem. Take line loose at carb, plug onto a vacuum/pressure gauge (they're cheap) and spin engine over with switch off---probably will show 4-5 #'s but 2.5-3 is enough. Next hold open line over a can and spin over 8-10 times, should put out 1/2 cupfull or so. If both fuel pressure and volume are okay then YOU HAVE AN AIR LEAK. It takes 15 parts air to one part gas for an engine to run so if it's air supply is cut off with the choke at the carb being closed then air HAS to be coming from somewhere else or it wouldn't run at all. Now hook your vacuum gauge to the windshield wiper nipple on the intake and start with the choke on to make it run and then open the choke and follow the gauge reading. If it drops below 15 inches there is an air bleed somewhere which prevents the cylinders from drawing in an air/fuel charge. If it runs ok with the choke closed this pretty much eliminates other low vacuum causes like timing, valves tight or bad, and restricted exhaust.
     
  6. bigtimjamestown

    bigtimjamestown Member

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    What Even says....

    Quote:
    Originally Posted by coilover View Post
    First, eliminate fuel as the problem. Take line loose at carb, plug onto a vacuum/pressure gauge (they're cheap) and spin engine over with switch off---probably will show 4-5 #'s but 2.5-3 is enough. Next hold open line over a can and spin over 8-10 times, should put out 1/2 cupfull or so. If both fuel pressure and volume are okay then YOU HAVE AN AIR LEAK. It takes 15 parts air to one part gas for an engine to run so if it's air supply is cut off with the choke at the carb being closed then air HAS to be coming from somewhere else or it wouldn't run at all. Now hook your vacuum gauge to the windshield wiper nipple on the intake and start with the choke on to make it run and then open the choke and follow the gauge reading. If it drops below 15 inches there is an air bleed somewhere which prevents the cylinders from drawing in an air/fuel charge. If it runs ok with the choke closed this pretty much eliminates other low vacuum causes like timing, valves tight or bad, and restricted exhaust.
    Also just to add a couple of things .....17-21 in. of steady vacuum is considered normal and you might also want to check the hose going to your wiper motor for breaks... Even you are one of the few people that I have heard of that knows that a vacuum gauge can also be used for other things and what the readings mean....Big Tim :cool:
     
  7. dan cocomise

    dan cocomise Member

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    only runs with choke closed

    before i clean carb .i will do the gas volume test and vacume test .when running at idal 17 -21 psi is that with choke open or closed. thanks
     
  8. bigtimjamestown

    bigtimjamestown Member

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    17 - 21 in. of steady vacuum would be normal at a idle. If you crack the throttle the vacuum will decrease. At a fast steady idle it will increase slightly.
     
  9. vwnate1

    vwnate1 Member

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    Vacuum Gauges

    FWIW ;

    I find the best ones cheaply in thrift stores , pawn shops and used tool places , they'll be American or German made and will usually have a rotted hose ~ who cares ? bargain the price down to where you like it (I rarely pay over $1.00) and look in the box of tools / junk for the tapered hose tip , that comes in really handy when you're using it .

    Or , buy a cheapo " Mity - Vac " brand vacuum tool , it's a combination vacuum pump and gauge , very handy , can be used to bleed the brakes too .

    Follow the use instructions given above to the letter ~ don't get creative nor think too much until you get familiar wit this handy tool and it's usage .
     
  10. Wolf

    Wolf Member

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    Could be a similiar issue to what I went through. There are tons of great diagnostic advice in here
    https://talk.classicparts.com/showthread.php?t=10753

    My solution was on Page 4.

    Let us know what you end up finding, just remember to eliminate variables. Make sure you have fuel to the pump from the tank. Then make sure you have fuel on the back side or coming through the pump. If that is ok, make sure you have fuel right at the carb inlet. If you do, then you have an issue in the carb. Clogged jets or passages. Or an air leak or some where. Get you a can of carb dip, sounds like you are. I use it all the time.
     
  11. dan cocomise

    dan cocomise Member

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    only runs with choke closed

    volume and vacume test was good at carb. i still must test vacume at manifold wipper outlet.then i will check cleaning carb. i will keep you posted i do not have ez acsess to inter net.thanks
     
    Last edited by a moderator: Apr 1, 2012

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