The check ball at the bottom of the accelerator pump piston chamber is for allowing fuel to enter the piston chamber via a passageway at the bottom of the float chamber. Atmospheric pressure will cause the ball to unseat and allow fuel to flow from float side to piston side when the pump piston is returning to the idle position. Thus, filling the pump cavity. When the pump piston is depressed during a throttle application, the ball is forced against it's seat to prevent the fuel in the pump chamber from escaping BACK into the float chamber via the delivery passage.
Got all that??...Ok....NOW...here is where the fun starts.
The engine will start....idle.....run....ACCELERATE....all that good stuff....even if the ball is MISSING!
As a matter of fact, if you left EVERYTHING out of that accelerator pump bore...The ball, the cir-clip, the piston, the return spring AND plunger...you would probably not notice much, IF ANY, difference in engine performance at all!!
That is...IF...IF.......all else is right with the carburetor.
Not trying to be a smart Alec with all the ...and all.... but I want to emphasize that these accelerator pump systems on these little carburetors are just not very good accelerator pumps. And, the engine will work really well without them even if you didn't put everything back "just so". So take comfort in knowing you didn't do anything "untoward" there.
I would guess that half the small displacement Honda engines running around right now have the accelerator pump piston SEIZED in the bore and the owner doesn't know it yet.
But here is where the "plot thickens". IF the accelerator pump PASSAGEWAYS are not COMPLETELY clean and fuel can easily flow through them.....the engine is not likely to run very well at all. That's right! The pump and check ball can be missing and the carb works fine. But leave a little blockage in the passageway and you will have problems.
It is almost as if the carb NEEDS those passages clear for the carb to BREATHE. That's the best way I can state it.
When I rebuild one of these, I use a pressurized spray can of cleaner and small wire to force the passages in the base of the float chamber clear. On the outlet side of the accelerator pump chamber, I make sure that passage is also clear. THEN where that accelerator pump passage MATES to the MAIN body, I use the spray to force cleaner into the accelerator pump OUTLET NOZZLE.
The outlet nozzle is in the form of a small brass tube that juts out into the carb throat at the front of the Venturi passage. The nozzle has a TINY orifice that points toward the back side of the carb. This is where fuel will spray out to enrich the mix when the throttle is opened up. IF THE PUMP IS FUNCTIONING.
I use a small, pocket type screwdriver to prop open the throttle linkage so that the throttle plate is completely wide open. Then I test to see if I have the accelerator pump passage clean enough by inserting the plastic straw that comes with the can into the passage so that I get a burst of cleaner coming from the tiny orifice in the brass tube. When the stream of fluid that comes out the back of the carb gets to be around 8 FEET LONG. I know I have the passage clear.
NOT 4 feet...not 5 feet....not 6 feet...but EIGHT FEET LONG! It's actually pretty incredible the first time you see it.
When you have that passage THAT clean, only then can you be certain the carb has a chance to BREATHE.
But first....let me ask you this:
Does your engine have the "fuel chamber" (item #2 in the parts link below)? If so, have you ever taken it off and cleaned it? If not, please do. it comes off by sliding it's little holder (item # 4) off of the engine oil dipstick tube. Take it off of the engine and shake all the liquid out of it until it is dry. Then reinstall and try the engine again. It just might run.
http://www.boats.net/parts/search/Honda/Outboard Engine/2004/BF15D4 LRA/FUEL PUMP (2)/parts.html
Good luck and let us know how you make out.
