Hot Start Issue Choke stuck?

Discussion in 'Fuel and Air Systems' started by bisblue, Nov 14, 2018.

  1. bisblue

    bisblue FABO Gold Member FABO Gold Member

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    Hey folks,
    New member. I fired up my 74 duster 56k miles, for the first time yesterday. It would run amazing then stall and not want to start when warming up (gauge just reading 120 degrees). Eventually I noticed the choke still engaged slightly, I fiddled to get it open all the way and it would fire up.
    I was using a gallon gas tank with a hose tossed in it, since I ordered a new tank that won't get here till Monday. I know the second owner replaced lots of parts when their grandpa died, but not the tank. It got rear ended in the 80s and parked till 2015,then they tuned it up then sat till I got it. My buddy drove it down the block then said the bad gas clogged it up.
    They replaced the VR, ignition module, fuel pump, alternator, coil, distributor, plugs, wires, starter.... I checked for spark when it was stalled and hot and got it.
    I replaced the VR as the gauge was wavering and reading high, and the ignition module as my buddy thought it was likely bad. He thought it was going to have some ignition stuff to work through. He bought it did a burnout and parked it for the last 6 months or so.
    Is there an easy way to adjust the choke thermostat to get it to open earlier on a Carter 2 barrel? Is it possible that some gunk got past the fuel filter, do I need to rebuild the carb after the bad gas tank?
    Sorry didn't get a picture without the air cleaner on. I'm way more of a diesel guy and have limited experience with carbs so all help is appreciated.
    Thanks in advance,
    Adam
    Barrel IMG_20181111_153659019.jpg IMG_20181111_154850590.jpg
     
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    • lilfontleroy

      lilfontleroy lilannoyingLeRoy FABO Gold Member

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      try some carb cleaner
       
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      • bisblue

        bisblue FABO Gold Member FABO Gold Member

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        I gave it a fair bit before starting, but I will hit it again.
         
      • lilfontleroy

        lilfontleroy lilannoyingLeRoy FABO Gold Member

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        while running give it some RPM and run a few shots in there also hit the choke pivot points
         
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        • halifaxhops

          halifaxhops It's going to get stupid around here! FABO Gold Member

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          You should have a choke pull off on the carb. Either bad or needs a adjustment.
           
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          • Garrett Ellison

            Garrett Ellison Amateur driver on public roadway, do not imitate..

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            Check and make sure your vacuum break is working properly and that the hose is not split/leaking. Choke temperature adjustment is done by bending the the rod out of the choke well on the intake to lessen or increase spring pressure. A good primer on these is on YouTube under Chrysler Master Tech
             
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            • bisblue

              bisblue FABO Gold Member FABO Gold Member

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              Thanks folks
               
            • Mattax

              Mattax Just the facts, ma'am FABO Gold Member

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              A relatively complete on-line set of Master Tech Booklets and filmstrips.
              Master Technician Service Conference - Chrysler's Training for Mechanics
              Be sure to check out '73 get em started, CAP, and Drivability.

              Old fuel sitting will leave varnish like residue. Fresh modern high detegent fuel may clean some but not likely all of this varnish. Winter fuel has high RVP and is problematic in hot weather.* Summer fuel isn't as bad but may have cold weather start difficulty. Reformulated fuel has components that may or may not deteriorate some seals and gaskets. Plan on cleaning and replacing seals and gaskets of the carb at some point sooner than later.

              *Fuel is different in different parts of the country. Your part of NV may not have a winter fuel.
              Date of switch to summer-grade gasoline approaches - Today in Energy - U.S. Energy Information Administration (EIA)
              Help Gasoline Characteristics, Street/Pump, then and now?
               
              Last edited: Nov 14, 2018
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              • Tooljunkie

                Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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                If choke was hanging up, it would be clearly visible with air cleaner lid off.
                Depending on ambient temperature it could be icing up too. The 318’s like the heat stove attatched and working.
                 
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                • bisblue

                  bisblue FABO Gold Member FABO Gold Member

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                  What exactly is the heat stove. I ordered a copy of the Haynes manual.
                  I just sold an old C20 Chevy pickup I had but the carburetor was a random replacement with no factory choke. I rebuilt it but there's a lot more going on with this duster choke setup.
                   
                • Garrett Ellison

                  Garrett Ellison Amateur driver on public roadway, do not imitate..

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                  You may also want to check your float height, i set mine from 1/4 inch recommenced height by my 1971 Motor’s Repair Manual to 7/32 to improve the hot start characteristics in the near 90 degree weather last summer, not that that’s (unfortunately) really a problem for me now in our balmy 31 degree mountain weather today... cabin fever started early this season...
                   
                • Tooljunkie

                  Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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                  There is an opening on the bottom of air cleaner snorkel, a flexible metal hose connects to a shield on exhuast manifold.
                  On damp days below 65 degrees the carburetor will form ice inside,cutting off fuel.
                  I witnessed this on my power wagon,it would start fine,start to warm up, then out of the blue it would stall.
                  Wait 10 minutes and it would be fine.

                  The morning i caught on,i had hood open and could see base of carb frosting up on the outside.
                  Added the missing parts and to this day,still starts and warms up without issue. 17 years later.
                   
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                  • Mattax

                    Mattax Just the facts, ma'am FABO Gold Member

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                    TJ covered it nicely. If you'ld like an illustration it was introduced here:
                    Heated Air Intake and "Vapor Saver" (Session 271) from the Master Technician's Service Conference

                    The best book to have is the Plymouth Service Manual. You may find a scanned edition on line for 74. I personally like to have a print copy as well.
                    A lot of scanned original sales info as well as service bulletins are here:
                    The 1970 Hamtramck Registry Library Page (1970 - 1974)

                    Your car may have a sticker under the hood with factory tune up specs and vacuum hose routing. I forget what year that started.

                    Factory carbs and timing of these years are calibrated a bit different than you would do with an aftermarket carb. Late 60s they focused on reducing CO and HC at idle and on deceleration. Then on reducing NOx as well. Mentioning this so you understand the goals of the original setup which is the baseline regardless of what you do.
                     
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                    • bisblue

                      bisblue FABO Gold Member FABO Gold Member

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                      Thanks,
                      Definitely no moisture here in vegas.

                      I think I saw the factory settings sticker.
                       
                    • Tooljunkie

                      Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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                      Vegas? Oh well in that case, pay my air fare and i will come help you fix er up. May even bring a spare carb.
                      Unless you can wait, will be there oct next year (sema).
                       
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                      • Tooljunkie

                        Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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                        No, i dont think cool air and humidity is your problem.
                        Cold start in vegas is almost operating temp.

                        Put a vacuum pump on the choke pull-off and see what it does. Shoul pull it open about 5/16”
                         
                      • bisblue

                        bisblue FABO Gold Member FABO Gold Member

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                        Seems like the choke is working smoother. I can see the pull off slowly working as it heats up. I carb cleaned a good bit adjusted the air mixture screws a hair out. Running great and smooth, until I try to shift into gear, immediate stall. I can hold the brake and feather the gas and will not stall for a little bit then dies.

                        I checked some electrical stuff tonight but that is not my strong suit. I fired it up in the dark with a mist of water and didn't have anything grounding out. I've got 14-15 volts, 13+ to 14- at the battery up to 15- in the cab. Maybe a bad voltage regulator? It has a newer one on it, and I ordered a NOS from Ebay buy it won't arrive until monday.

                        Ignition Control Module is also newer, with a made in the USA one in the trunk. Wouldn't start with older one.

                        Gas tank will be a bit so I'm running a fuel line off the pump into a clean fuel can.

                        I'll toss some photos up but my cable isn't working

                        Thanks again for all the help folks
                         
                      • Mattax

                        Mattax Just the facts, ma'am FABO Gold Member

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                        Most of the carbs with idle scres that controlled air have a left hand thread. So turning them clockwise moves them out, leaning the mixture. This was to make it less confusing as turning a standard idle mix screw clockwise reduces the idle fuel mix.

                        Richer usually sounds smoother. Hard to explain. However not being able to accept load is usually too lean and too much advance. All I can suggest is keep careful track of the changes made and test at 1/8 or 1/4 turn increments.

                        Check at the voltage regulator. If it is 'seeing' 13 volts, when the voltage at the alternator output is 15, its because there is resistance in the wiring. The regulator is doing the correct thing based on the information it is getting (system voltage is lower than target of approx 14.2 Volts).

                        Not likely the issue based on the situation.

                        That's plenty. Gravity feed is fine for putting around. It just needs to keep the bowl full. It may be a little low since the pressure on the needle is a little less. Float setting is important but again since it was running before it doesn't point to this as the problem of dying in gear.
                         
                      • Dana

                        Dana FABO Gold Member FABO Gold Member

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                        What do you have the idle RPM set at? If you don't have a tachometer, then how many turns are on the curb idle screw? I'd like to know if you are idling on the idle circuit or the main circuit.
                         
                      • bisblue

                        bisblue FABO Gold Member FABO Gold Member

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                        Just hooked up a tach tonight. About 1000 when it runs smoother.

                        I turned the mixture screws counter clockwise about 1/4 turn to sound better. When it does stall I've gotta pump the gas a bit to get it going. Sometimes it will sound like it might start right when you let off the key, but then it doesn't. Almost sounds like it's dieseling as it dies.

                        Didn't get to test the regulator just yet.

                        Out of curiosity and not to sound too blasphemous, is their a mopar equivalent of the stand alone HEI distributor for SBC?
                         
                      • Mattax

                        Mattax Just the facts, ma'am FABO Gold Member

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                        At 1000 rpm, throttle is probably too far open to be getting much effect from the idle mix screw(s). Sounds like it may be on the fast idle cam, which means its still warming up.
                         
                      • bisblue

                        bisblue FABO Gold Member FABO Gold Member

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                        Here is how the idle screw is set. Not sure exactly how many turns.

                        Also whatever this metal covered line is coming off of the radiator, it's super loose at the connection. Man there sure are a lot of vacuum lines on this bad boy. I bought a couple feet of vacuum line and replaced any that looked worn.
                        IMG_20181114_173409912.jpg IMG_20181114_173415085.jpg IMG_20181114_200431660.jpg
                         
                      • bisblue

                        bisblue FABO Gold Member FABO Gold Member

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                        It was just getting over 120 degrees, I haven't really been able to get it super hot idling. It's about 55 degrees here in Vegas.
                         
                      • Dana

                        Dana FABO Gold Member FABO Gold Member

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                        That carb should not be a reverse idle system. Did you try backing the idle mixture screws out further than the 1/4 turn you mentioned? And how many turns out from bottom are they?
                         
                      • Mattax

                        Mattax Just the facts, ma'am FABO Gold Member

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                        I'll tell you what I see. But I think your best bet is to look through the tech bulletins to get yourself up to speed on the carb and choke concepts and what should be on your car. You'll probably be able to post some more photos with specifics on whats on there now.

                        The braided hose looks to be attached to an EGR valve on the intake manifold and a temperature actuated valve on the radiator. The EGR valve, if it is one, is opened when engine is warm, the throttle is at least slightly above idle, and the manifold vacuum is high. Since there is no hose to a vacuum source, its out of the picture for now.

                        Not sure what is going with the two idle speed screws in the right hand photo. Most emmissions era carbs have a solenoid actuated idle stop. Cars with A/C often have a two position solenoid for slightly higher throttle opening when the A/C is on.
                        The fast idle cam and fast idle screw is usually on the passenger side of the carb.
                        Verify my observations are specific to your car. Each year and combo is a little different. On your two barrel carb one may be for throttle stop[position w/o solenoid and the other might be fast idle.
                        There's a thread somewhere in the Tech forums, I think its at the top, titled something like Free Manuals. That should lead you to a '74 FSM. Dodge will be similar if you cant get a Plymouth one right away.
                         
                        Last edited: Nov 14, 2018