Posted by Sherman in Idaho [24.32.202.166] on Wednesday, September 25, 2013 at 00:27:57 :
In Reply to: Accelerator pump adjustment. posted by Sterling Luttrell [99.58.180.94] on Wednesday, September 25, 2013 at 00:07:14 :
Depending on the carb, you only have a few choices, maybe 3 holes in the shaft that you can use. If the pump is not working, the engine will hesitate or die when you open the throttle suddenly. Make sure the pump has good soft leather. Old ones that have been dry for a long time don't work. To see if it works, look down the carb and open the throttle quickly, you should see a good squirt of gas go in. The engine doesn't need to be running for this. To adjust it, just try the middle position and see what happens when you tromp the gas. If it doesn't hesitate, it's good. If it does hesitate, try the "longer stroke" hole next and see if it gets better or worse. If it's still not good, try the other one. There aren't many choices so "trial and error" is fine. If you have a vacuum advance, make sure that's working right first, because if it's not, it will cause a similar problem.
When I think about it, the only real problem I've ever had with any old carburetor is the accelerator pump not pumping. I hate to buy a rebuild kit just to get the pump plunger, but that's all I end up really needing. In general, "works" versus "doesn't work" is the key thing, and you shouldn't have to work much magic into the adjustment. It seems like mine always end up getting set to the longest stroke position.