55 Tbird - hesistation on acceleration

TommyDanger

TommyDanger

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Joined
Jan 29, 2019
Thunderbird Year
1955
My 55 tbird is having acceleration issues. The motor hesitates and sometimes dies out when I push on the gas pedal from a stop. It is more heavier of a hesitation when the motor is cold. I can drive the car but I have to slowly accelerate from a stop or I risk stalling the motor. I recently rebuilt the carb with a carb kit and maybe I didn't install something correctly. Any ideas on what I should check first? The fuel filter seems fine. There is fuel in the float bowl in the carb. Oh and I have the stock Teapot carb. Thanks
 

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Have you Checked the acceleration pump? Work the throttle from Idle position to wide ope with the engine not running and see if the pump is squirting fuel into the venturies (sp). If that is working check for any vacuum leaks or vacuum line that maybe didn't get reconnect after the carb rebuild.

Take care
Ed
 
I had my carb professionally rebuilt by Larry's. It made a world of difference in how mine runs and idles. I still have a very slight hesitation when coming off a red light, but never stalls. The problems when cold are probably caused by the auto choke. I had attempted to fix the choke before the rebuild, and even bought a new choke coil. But I could not get the adjustments right. The rebuild also fixed the cold-running problem.
 
Is the accelerator pump putting out a strong enough "shot"? I would increast the shot to see if that makes a difference
 
From your description it sounds as though your carburetor has very poor or no transition from idle to ventura boost. Poor transition is usually caused by an ineffective accelerator pump. Some of the causes are the inlet check ball and its retainer. Does the ball seat properly? Is the pump discharge needle valve in place and does it seat? Is the float level high enough? It should be 1/4" below the top edge of the fuel bowl. If set too low, the carburetor will have poor transition.

Another cause of poor transition is a too lean idle mixture. This is most often caused by atmosphere leaking into the idle passageway at the point where the fuel bowl foot attaches to the throttle body. Proper assembly at this point is critical. The protruding foot of the fuel bowl is usually warped so bad it will not seal.

doug7740
1955 Thunderbird Blue
 
Before everybody goes off the deep end. Check this out. I had a 1956 Chevy 6 cylinder and it got to doing the very same thing that TommyDangers Tbird is doing. I could press on the gas and it would take off and then die. I could slowly press on the gas and it would get up to 60 with no problem. What I found was a failing fuel pump. It was pumping just enough gas at idle to fill the fuel bowl and then if i took off fast it would die. You have a bad fuel pump. Cheap and easy to change. Let me know what you find out.
 
Agree with Dale and would add that the float may not be adjusted correctly and the fuel level in the float bowl could be too low.
 
Thanks for all the help.

I checked for the ‘squirt’ from the accelerator pump. Looks like a good shot on both sides.

Float bowl has fuel and float is set correctly.

Next I’m going to check for vacuum leaks...

Then idle mixture screw setting...

If that checks out, then I’ll look into the fuel pump.
 
Just remember what I said in my post. Everything was normal except for the fuel pump.
 
TommyDanger said:
My 55 tbird is having acceleration issues. The motor hesitates and sometimes dies out when I push on the gas pedal from a stop. It is more heavier of a hesitation when the motor is cold. I can drive the car but I have to slowly accelerate from a stop or I risk stalling the motor. I recently rebuilt the carb with a carb kit and maybe I didn't install something correctly. Any ideas on what I should check first? The fuel filter seems fine. There is fuel in the float bowl in the carb. Oh and I have the stock Teapot carb. Thanks
Click to expand...
Most likely the jet is not aligned to shoot straight down and is hitting the wall
 
Oly Bob R said:
Most likely the jet is not aligned to shoot straight down and is hitting the wall
Click to expand...
Remember it was running good and then started having this problem. Jets don't get out of adjustment unless they are messed with.They don't bend out of adjustment on their own.
 
Dale Leonard said:
Remember it was running good and then started having this problem. Jets don't get out of adjustment unless they are messed with.They don't bend out of adjustment on their own.
Click to expand...
Agree however he said he rebuilt the carb and may have it slightly out of alignment
 
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