1956 flooding/vacuum issue

[Pete G]

I have a 1956 with the original 312 V8 and Holley carb (which was rebuilt a few years ago). She starts up fine and drives beautifully, but after i turn her off, she doesn't want to start back up again unless i let her sit for several hours. I'm thinking it is a flooding or vacuum issue, but i'm not a mechanic and just guessing. Any help would be appreciated, thank you!

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[zeroroadkill]

Can you describe your re-start procedure?
Are you pumping the pedal? Holding it down? Sometimes a hot engine will evaporate the fuel in the carburetor requiring a few pumps. Flooding requires holding the pedal to the floor. So tell us how you try to restart.

 

[Pete G]

Can you describe your re-start procedure?
Are you pumping the pedal? Holding it down? Sometimes a hot engine will evaporate the fuel in the carburetor requiring a few pumps. Flooding requires holding the pedal to the floor. So tell us how you try to restart.

Hi Zero - I usually pump the pedal. I've tried not pumping the pedal, doesn't seem to work, and sometimes holding the pedal to the floor usually eventually works, only after a long period of time.

 

[Ward 57]

Hi Zero - I usually pump the pedal. I've tried not pumping the pedal, doesn't seem to work, and sometimes holding the pedal to the floor usually eventually works, only after a long period of time.

Make sure you have the proper gaskets under the carb. Heat soak will boil the carb dry when stopped if too much heat from the manifold is over heating the carb.

 

[zeroroadkill]

If you have to hold the pedal on the floor to get it restarted this may indicate flooding. Why this may be be happening after driving could be heat boil-over), or vapor lock maybe?

Is your fuel filter bowl full after sitting?
Like mentioned, do you have the proper stacked gasket under the carburetor? I just had to order mine.
Is your gas cap vented? Do you get rushing air sound when you open it?
Are your fuel lines away from the intake manifold?
Timing, are you tuned to the proper advance?

So many causes….

 

[Gail 56 bird]

If you have to hold the pedal on the floor to get it restarted this may indicate flooding. Why this may be be happening after driving could be heat boil-over), or vapor lock maybe?

Is your fuel filter bowl full after sitting?
Like mentioned, do you have the proper stacked gasket under the carburetor? I just had to order mine.
Is your gas cap vented? Do you get rushing air sound when you open it?
Are your fuel lines away from the intake manifold?
Timing, are you tuned to the proper advance?

So many causes….

What is the proper stacked gaskets under carburetor?

 

[zeroroadkill]

Post in thread '1955 Teapot float level'
https://forums.fordthunderbirdforum.com/threads/1955-teapot-float-level.15235/post-91774

 

[Pete G]

Post in thread '1955 Teapot float level'
https://forums.fordthunderbirdforum.com/threads/1955-teapot-float-level.15235/post-91774

Yep, that is the new gasket i put on after the carb was rebuilt. Ran great for a couple years. I'll try to go through the rest of the checklist you provided, thanks.

 

[doug7740]

Hi Zero - I usually pump the pedal. I've tried not pumping the pedal, doesn't seem to work, and sometimes holding the pedal to the floor usually eventually works, only after a long period of time.

Pete,

Here is the starting procedure that I use:

Cold Engine - Sitting Overnight - Sitting For A Few Days​

Do not touch the accelerator; crank the engine over for 5 seconds. This not only fills the fuel filter bowl with fuel, it also builds up oil pressure.

Slowly push the accelerator pedal to the floor and then slowly release the accelerator pedal. This closes the choke assembly and primes the carburetor with fuel.

Do not touch the accelerator; crank the engine over for 5 seconds once again. If the engine starts, rev the engine once slightly.

If the engine did not start, depress the accelerator 3 times, but only ¼ pedal travel each time. This primes the carburetor with additional fuel, but keep in mind, T-Bird engines flood easily. Crank the engine over once again and when the engine starts, rev the engine once slightly.

Warm Engine - Sitting Less Than An Hour​

Do not touch the accelerator; crank the engine over and when the engine starts rev the engine once slightly.

Warm Engine - Sitting More Than An Hour​

Depress the accelerator pedal ¼ pedal travel and hold it in that position. Crank the engine over and when the engine starts rev the engine once slightly.

doug7740
1955 Thunderbird Blue

 

[dustcollectorcoke71]

Why does my 1956 Thunderbird run great for ten minutes and then runs rough?

 

[zeroroadkill]

More details needed:
Temperature gauge reading?
Engine Hot?
Speed?
Outside temperature?
Type fuel?
Stock fuel pump?
Fuel filter condition?
Filter bowl level?
Vented gas cap? Not sure if the 56 had a vented gas tank vent unlike like the 55?

 

[Ward 57]

I'll go with the non vented gas cap.

 

[zeroroadkill]

If I’m not mistaken, the 56 and 57 have a vented gas tank so you don’t need a vented gas cap but the 55 does not have a vented gas tank and when I first got the car, I would notice a air rushing sound when I opened up the To fuel it up, which means it was forming a vacuum which could lead to fuel pump failures to pump fuel as it tries to overcome the vacuum.

 

[Ward 57]

If I’m not mistaken, the 56 and 57 have a vented gas tank so you don’t need a vented gas cap but the 55 does not have a vented gas tank and when I first got the car, I would notice a air rushing sound when I opened up the To fuel it up, which means it was forming a vacuum which could lead to fuel pump failures to pump fuel as it tries to overcome the vacuum.

They were fixing issues all through the three years in the production lines. That may have been one of them you don't hear about.

 

[dmsfrr]

'55 to '57 T-Birds do not have vented gas tanks and should have a vented gas cap.
'57 Bird's do have a vent tube along-side the filler neck to help let air bubbles out of the tank... But it's connected back into the filler neck below the gas cap, which needs to be vented.
.