Carter YF Accelerator Pump

I'm rebuilding my Carter YF out of a 59 CJ5. The acc. pump was frozen so I wasn't getting any action to see how it operates. I put the new one in and it pushes down about a half inch although according to the manual it only goes half the distance when operating.

My problem lies in understanding its operation. There is the mechanical arm that is attached to the acc. shaft but it is set up so that you can not physically push the pump rod down. Are these only operated by vacuum? and if so, it seems like it would take a substantial vacuum to move it. Also, wouldn't this allow no action when stomping on the foot accelerator to prime the engine before start?

I'm thinking someone may have rebuilt with wrong parts since they used a wrong gasket already. So, basically I don't see how the pump can move without vacuum. I also followed the service manual and everything is in the right place.

 

Don't know specifically about your question. However, the YF was used well into the '70s on Jeeps. Look here http://oljeep.com/edge_74_tsm.html at the chapter on carburetors. The manual has an excellent description of the circuits of the YF and how they work together. If you got the right rebuild kit, there should be instructions in the kit for setting the various adjustments of the carburetor.

Also, there has been a lot of discussion of which kit to get for these early YFs, so that you get the right float needle and maybe other parts. Search old posts for more info.

hth!

 

x2 on "Brian P"