Technical ROCHESTER BC ACCELERATOR PUMP ISSUES

I recently opened my rochester bc (shouldn't have looking back...) to replace the gasket as it was leaking slightly. While I did that I figured might as well replace the accelerator pump cup with the (1) from the rebuild kit (second mistake). My problem now, is I can't get a full squirt with the pump. Passage is clear, check ball is fine, pump bore is clean, etc. When it's apart and I activate the pump, it moves very slowly/not the full travel and no squirt, just a dribble. If I actually move the pump plunger, I get an appropriate squirt. It's like the delayer (think that's what it's called) spring is too weak. Do these springs need replacing? All the replacement pump****embles I've seen don't include the spring.

Thanks in advance.

Ryan

 

Is the cup out to the edges of the pump chamber?

 

Maybe put the pump in gas outside the carb to swell slightly then install it in the carb. You probably don’t remember the old leather pumps. You absolutely had to do that on them or they flat would not work.

 

Jimmy-yes the cup is all the way out and making a seal.
Kevin-yes I presoaked the rubber replacement cup.

That said, the new cup is plenty tight in the pump well, almost too tight as like I said the spring seems too weak to move it.

Let me find some photos.

Thanks,

Ryan

 

This is just the spring pushing the plunger.

This is after I “assist” the plunger.
The spring is obviously not pushing the plunger through its entire travel.

Thanks for the input so far!

Ryan

 

Took it apart again and per carburetor mike's youtube video, put some lithium grease on the cup. This worked until the grease went away and now I'm back to where I started. Getting to the point where I'm just going to replace the carb...

Thanks again for the input,

Ryan

 

Maybe the passage is blocked, and what you were essentially doing is hydraulicing the circuit. Pull that spring and check ball out and see if it will squirt out of that chick ball hole. Sounds to me like the circuit is blocked causing excessive pressure in the well.

 

Damm this sounds familiar and horrible. I went through this and after losing a few more of my irreplaceable hairs, found the solution. Take a piece of crocus cloth and polish the inside of the pump bore-totally. Do not use any form of fine sandpaper as it will leave scratches that drag the pump. When finished, get it totally clean and then put some light oil or lithium grease (very light coat) on the bore just for the initial start. Make sure the pump part is right-not crooked or*****ed.
Didn't work?
Look for huge dumpster.

 

Clean smooth bore is key. Had a 2G Rochester act up like yours. Polished the bore AND also replaced cup seal again not using the prior cup seal that had been getting stuck in unpolished bore.

 

Thanks guys! I’ll try both of these and report back!

Ryan

 

If you put anything other than gasoline in the tank (ethanol, octane boost, heet, etc.) a genuine leather accelerator pump is your best friend.

Jon

 

Well, upon closer inspection the bore is fairly scored. With my initial visual and finger feel, I didn't notice it was scratched. I polished it, new cup (new****emble as cup alone was not available), light grease, and reassembled. 1 thing I noticed was the new cup was visibly small in diameter. Careful measuring of the 2 showed .02 inches. New one went in the bore a lot easier. I've tested it, and I have a good squirt for now. If it starts acting up again, probably time for a new carb.

Thanks again for all the insight!

Ryan