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Carb probs, 73 charger

Started by dolphinron, August 17, 2011, 06:42:58 PM

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dolphinron

I have to spray choke and link cleaner directly in my carb to get it going if my car sits for more then a day.  Otherwise it wont start no matter how many pumps of accelerator or lack of to prime.  I have a carter 4bbl on my 440.  Any suggestions to a rookie mechanic on what to adjust or do.  Also I use regular 87 octane.  Thanks

Chryco Psycho

Look in the throat of the carb & watch to see if it is spraying fuel in as the throttle is opened , it could be a bad or weak pump diaphragm , it could also be a worn fuel pump pushrod not cycling the fuel pump enough to refill the carb after the fuel evaporates , there is a stepped down section on both ends of the pushrod , they should be equal length on both ends  This can be tested with a fuel pressure guage but it is better to measure the rod . Also the fuel level could be set too low inside the carb , typically it will call for 7/16 on the tip of the float , I generally raise it a bit more to work best .

chargd72

Get a carb rebuild kit.  They come with step by step instructions that are very easy to follow.  I used to have to crank on my Eddy 600 to get it going, now three pumps at the pedal, turn key and it fires right up everytime. 

          '72 Charger SE 4bbl 318                          '76 Power Wagon 400 W200                                 2011 (attempt at a) Charger

flyinlow

I assume by Carter, you have the original Thermoquad carb. Once you get the car started does it run well and make good power?

I would check the carb accelerator pump first. After you run the engine for a couple of mins. shut it off and remove the air cleaner. Look down the primary throttle bores of the carb as you quickly open the throttle. You should see what looks like a small squirtgun of gas shoot into the throttle bore on each side as you open the throttle.

dolphinron

flyinlow, I will try that. When it is running it runs pretty good but does bog on some starts from red light.  It almost dies from start at light some times.

dolphinron

After I drove it a while came home with car off, looked in bowl while pumping throttle and saw no fuel shooting in bowl anywhere.   :shruggy:

Cooter

Gentlemens, Remember with Ethanol in the Swill they loosely call "Fuel" today, it allows the consumption of water. Therefore, the next time you pull up to the pump, how much of that 10 or so gallons of "Fuel" you just pumped into your tank was actually fuel? How much was water soaked up by the Ethanol?..

After shutdown, the fuel with alcohol in it evaporates VERY fast compared to the fuel of 10 years ago..Even as short as a couple days.
Not saying you might not have pump/carb problems, but the next time you are wondering why you are only getting 9 MPG, remember that it takes about 2 parts Alcohol to make the same power as ONE PART Gasoline....the translates into poor fuel economy for gallons purchased.

It kills me that at most of the pumps round here, we still have offered "Regular NON Ethanol" fuel for about 25 cents more Per Gallon, but people will buy that cheaper 15% Ethanol crap and wonder why their fuel mileage went down....
" I have spent thousands of dollars and countless hours researching what works and what doesn't and I'm willing to share"

flyinlow

Quote from: dolphinron on August 26, 2011, 08:19:28 PM
After I drove it a while came home with car off, looked in bowl while pumping throttle and saw no fuel shooting in bowl anywhere.   :shruggy:


Sounds like the accelerator pump is not working. When this happens the engine can hesitate from a traffic light and be hard to start which you have mentioned.

The pump gives the engine a little shot of fuel as the carb goes from its idle circuit to the main metering circuit to cover a temporary lean condition that most carbs exhibit. The pump also gives the engine a shot of prime on a cold engine start as you push the gas petal down to set the choke on the first start of the day.

Check that the rod that operates the pump is free to move. It is a rod with a couple of bends on the drivers side that goes between the primary bore linkage (front bores) to the pump lever on the top front of the carb. Again I am assuming you have a Thermoquad carb ,you said you have a Carter carb and that is what came on a "73.

flyinlow

does your carb look like this?

flyinlow

Things that can cause the accelerator pump not to work:

External, linkage missing,damaged or binding.

Internal, pump seal is worn or hardened from age, the pump check valve is gummed up or the small plastic tube that the fuel runs through from the pump to the discharge nozzles is damaged or fell off.

A can of Gumout in the tank might remove any gum in the check valve. Probable won't fix your problem ,but it is a simple ,cheap thing to try.

dolphinron

Yup flying that is my carb in the pic.  I will see if rod moves if I can figure out which one it is.  Is the rod in the pic of the carb you posted?  told ya I was novice mechanic.  I will also try the gumout.  Is putting a new accelerator pump hard to do?  thanks for help

flyinlow

The pump linkage is a bent rod ,a lever attached to the airhorn (top) of the carb with a screw at the pivot point and a S shaped link attacking the lever to the top of the pump plunger. As you open the throttle the pump plunger will descend into the carb body. In the picture the linkage is the closest to the camera. It is probably OK on your carb, it just the easiest thing to check and it is not inside the carb.
The Thermoquad can be a challenging carb to rebuild ,due to the many interrelated adjustments on it. I would recommend a '73 factory service manual, it has a step by step rebuild procedure with many pictures. Available on Ebay as a manual or CD. Carb kits are still available for the carb, but tuning parts are limited because it has been out of production for 25 years.
Do a search on Thermoquad or Demmon Sizzler for some info on the carb.           

dolphinron

flyinlow, you called it.  I finally got around to checking that linkage to see if it moves, and sure enough the arm linkage was just hanging there and not connected on the lower end to anything.  Thanks you got it.  You the man.  Dont have to rebuild anything now.  I love it.  Have a good one.

flyinlow

Glad you got it fixed.  :2thumbs:

Craig