hesitation with acceleration

[68Mustang]

have a stock 200 with original carb. If you get on the gas quick it will bog down and actually cut off if you dont back off. Once you back off and ease back down it will take off and accelerate fine. Runs well at highway spedds and idles fine.
Thoughts??? Have not changed the fuel filter.

 

[rbohm]

8) several things come to mind;

the carb may need rebuilding
the ignition timing is off
the vacuum advance isnt working properly
vacuum leaks

chances are the carb probably needs a rebuild.

 

[bubba22349]

For sure check out that fuel filter

 

[Frankenstang]

I'll throw out another...accelerator pump. It manages the transition from low throttle to high throttle when you mash the pedal by delivering the shot of petrol the engine lacks, while vacuum temporarily plummets with the throttle plate flung open. If you can 'soft shoe' her from the low range to the high range and run steady at any static point along the way...it's a good bet. Good luck

 

[jimlj66]

I don't know if I'm using the right terminology here but....
Look at the actuator arm that presses on the diaphragm on your accelerator pump. There should be no gap between them. On my carburetor I had about .030 gap, which translates to about a 1/4" throttle opening. I had to remove the linkage that operates the actuator arm and bend it (make it shorter) until the arm touches the diaphragm. If it is adjusted properly you should be able to look down the throat of the carburetor and have a squirt of fuel AS SOON as you start to move the throttle. If not it acts like a huge vacuum leak like Frankenstang mentioned.

 

[68Mustang]

Great points. Im will work with it this weekend and see what I come up with. Thanks!

 

[jamerson84]

I had to remove the linkage that operates the actuator arm and bend it (make it shorter) until the arm touches the diaphragm.

Does anyone know the Spec length of this accelerator pump arm? Having a similar prob with my 1100 but only when the car is at running temp. When it's on the cool side, and the engine is still warming up it runs great, no hesitation or flatspot. As soon as it warms up the flatspot comes back.
Ive tried lengthening the linkage but it didn't seem to help. Ive replaced the Accelerator pump because the old one was leaking but that also did not have any effect. I have a feeling that it's just not getting enough fuel. Not sure what I can do to get more fuel out of the acclerator pump.

This is a 65 stock 200 with a T5 five speed and a stock 1100 from Pony carbs with one Accelerator pump.
I had this issue years before and sent the carb back to pony carbs and it was fixed for a while but now the problem has returned. few months ago I tried to call pony carbs about the problem but was very sad to find out that they had gone out of business.

 

[78merKri6]

Hello 6 8

In addition to these other good suggestions, use a flashlight,look in the carb throat and watch for early, full pump shot.
These carbs may use 2 sizes of check balls--- there could be one missing, missplaced or not right size for hole. I think there are 4 in all. 1 inlet, 1 check, 1 dis-
charge and if automatic,1 for dashpot.

Also the check(or inlet) ball may need reseating. Drop correct ball into passage to seat, use a blunt punch or similar object against it, then tap punch with maybe a medium screwdriver handle. if this helps but maybe needs more you'll have to make more tries.

Remember, as has been said, these are great cars and engines. They are old but not
useless. They will require care,patience,determination.

Another thing, you may have a leaking advance diaphragm.

Press on. Good luck.

Gary

 

[jamerson84]

Thank you. I will keep at it.

 

[Frankenstang]

Hey Jamie,
EDIT: Mike's Carburetors has some great info that can help you navigate around 1100 tuning, check out this page...
http://carburetor-blog.com/?page_id=246
The youtube vid linked on that page gives the correct 'how to' on the accel pump shot adjustment (depicted the same as described in the Fomoco Shop Man...IIRC)...here's the direct link to the vid...
http://www.youtube.com/watch?feature=pl ... VbZ1W1oNxA

When it's on the cool side, and the engine is still warming up it runs great, no hesitation or flatspot. As soon as it warms up the flatspot comes back.

If the flat spot is not present when she's cold (choked or partially choked), then that would make me think she's leaning out once warm. Could be the pump shot, but could also be something like float setting out of adjustment. Float inspection and float settings may be worth giving a look.
Good luck
EDIT 2: PS Also looks like he did a full rebuild vid relatively recently (May 2012)...this is labeled Part I, I assume there's a part II... 8)
http://www.youtube.com/watch?v=eAirfexk ... ure=relmfu

 

[jamerson84]

Went through the carburetor today. Turns out my float valve setting was off by a good bit (on the lean side). I adjusted it as well as the Accelerator pump shot adjustment. The acceleration is much better now. There is still a slight bog or flat spot if you really get on it without easing into it first, and I still need to retime the engine again, but these adjustments have made it a lot easier to drive. Thanks again for the help and info. :mrgreen: