Ford 3000 Holley Carb

My Ford 3000 3cyl starts good with choke all the way out but then requires the choke 1/3 to 1/2 way out in order to drive or pull. It sputters if the choke is not out. I have new plugs and points and also went through the Holley carb and did not find anything unusual when cleaning it. It seems like a big vacuum leak somewhere. The gas flow from the pump is fine.
I suspect the problem is related to the brass vacuum piston accelerator pump. It did not look worn but then I do not know how tight it is supposed to fit in the aluminum carb body bore. There seems to be a lot of complaints with this carb related to a vacuum leak type condition.
I wonder if anybody has really determined what is actually going on. I bet the thing would run better if the vacuum accelerator pump piston was completely sealed so as to prevent any vacuum leak there. In other words run without any accelerator pump at all! If it was not so difficult to remove the thing I would try that!
The other strange thing was that there is a rubber disc in mine that is located where the pump piston lands when the spring forces it down under low vacuum condition. It is just freely positioned in there and free to flop around when the piston is held up against the spring under high vacuum condition. This disc is not shown anywhere on the parts diagram. It does seem to be the same diameter as the recess machined in the pump piston face as if it were meant to be held in that recess, but there is nothing to hold it in that position.
Sorry to ramble on so much but I am hoping someone out there has figured this out and I wanted to provide all the info I had.

My experience has taught me that most of the complaints about the Ford Holley tractor carburetors are due to improper rebuilds, e.g., using low quality aftermarket kits with incorrect gaskets.

Dean

http://ytforums.ytmag.com/viewtopic.php?t=572172&highlight=holley

I have had good luck fix'n them with a TISCO kit but I have done more carb work than the average bear.. Those carbs can not be beat when they are right,,, I sold U-dawg a kit this summer and he reported a fix 8)... When you give up i would like to have the Holley... As far as the rubber seal I will have to look at a drawing when I get the time... I vote for a gasket issue if every thing is free and no restrictions... I have had to make my own gaskets in the past

There are only 2 gaskets on mine and only one of them has anything to do with the vacuum system. If the carb kit only contains gaskets, it is not worth the cost, I made the gaskets using using a good gasket material and they turned out fine. The rubber disc in mine is a mystery and does not show up on the new holland parts diagram!
It just seems to me that there will always be air sucking past the brass pump piston causing a lean condition. You would think there would be a rubber seal around the piston to prevent this like on most auto accelerator pumps!
I still wonder why this tractor needs an accelerator pump at all when most all others do not! I bet it would run better with the pump blocked off and the vacuum leak eliminated altogether.

(quoted from post at 18:49:06 11/11/11) There are only 2 gaskets on mine and only one of them has anything to do with the vacuum system. If the carb kit only contains gaskets, it is not worth the cost, I made the gaskets using using a good gasket material and they turned out fine. The rubber disc in mine is a mystery and does not show up on the new holland parts diagram!
It just seems to me that there will always be air sucking past the brass pump piston causing a lean condition. You would think there would be a rubber seal around the piston to prevent this like on most auto accelerator pumps!
I still wonder why this tractor needs an accelerator pump at all when most all others do not! I bet it would run better with the pump blocked off and the vacuum leak eliminated altogether.

Click to expand...

Its probably no good send it to me... A TISCO kit will have what you need to repair it (New pump plunger 2) when they are right they can not B beat... If you disarm the pump you mite as well buy another carb and cut yer losses...

The extra rubber part you found does not ring a bell with me...

The carb is on the tractor and it starts and runs good as long as you provide some choke. I will continue to operate it that way I guess. A new piston might help but I sure did not see any wear on it. I wish I had it apart again to determine how the pump works. I wonder how the gas flows from below the piston into the manifold and how the air gets to the piston and into the manifold causing the lean condition. I just hate to take if off again to find out! I wish there was a diagram somewhere that showed the gas and air circuits in this carb! Someone could do the Ford world a great service providing one since these are notorious problems as evidenced on this board.
The extra rubber disc probably just bobbles around beneath the piston as it is held up by vacuum normally. It is a prefect fit into the recess machined in the bottom of the piston however and looks as if it were intended to be held in there although there is nothing to retain it unless it were just glued against the piston bottom. Strange!
You sound like you have experience with these Hollies and I sure wish we could go through one together, I bet we could figure it out! Where are you located anyway?