How Tight Should Accelerator Pump Plunger be in the Bore? (1 Viewer)

[katwalk]

So I got a call from the re-builder and discussed what I was seeing. As mentioned above he felt like there was trash blocking the nozzle, but would send me another plunger if I wanted. I told him to hold off until I had a chance to clean out the nozzle. Cleaned the nozzle, still no joy, so I pulled that carb of the and back to the work bench. I pulled the top off the carb and cleaned the nozzle again. With the top of the carb removed, I noticed when I pushed the plunger down, fuel would spit back into the bowl via the hole at the bottom of the bore (assume the hole is to regulate the amount of fuel in the bore) and also bubble up around the discharge weight stopper, but nothing would come out of the nozzle. I pulled the discharge weight stopper out, put my finger over the hole the stopper was just removed from and pushed the plunger down - lo and behold I got a nice healthy squirt out of the nozzle. Thinking I had maybe dislodged a piece of trash, I put the discharge weight stopper back, pushed the plunger down but no fuel coming form the nozzle again. Back on the phone with the rebuilder tomorrow...

 

[thebigredrocker]

Was there a steel ball under that weight? If carb is still apart you could confirm the big steel ball is under the weight in discharge chamber. And the small steel ball is under "e clip" in the plunger chamber. As FJ40Jim has said "small ball -big hole , big ball -small hole"

pic of discharge contents

 

[Mark W]

What you are calling "the discharge weight stopper"... the aluminum piece with a spring and check ball underneath it... If not trapped in place by the carb top, will let fuel bleed up out of the well and not build enough pressure for a strong (or any?) squirt out of the jet. The test with your finger on top was more accurate. tested with your finger holding it all in place would be the best.

If fuel is flowing back into the bowl through the inlet passage for the pump at the bottom of the pump bore, then the check ball is missing. There should be a spring clip holding a check ball into a seat at the very bottom of the bore.

If the fuel is flowing back from the relief cut at the top of the bore... that is normal.


Mark...