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Author Topic: Accelerator Pump Woes  (Read 838 times)

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Offline theofam

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Accelerator Pump Woes
« on: March 15, 2012, 11:13:51 AM »
Anyone know why my 1 & 4 accelerator nozzles aren't getting fuel on my 750 K8?  The fuel tube from carb 2 to 3 fills:



but the tubes from carb 2 to 1 and carb 3 to 4 stay dry:



I had the carbs off the bike yesterday and the portions of the carbs that feed the accelerator pump's fuel tubes from carb to carb all flow fine when carb cleaner is shot through them.  As some history, a year ago I rebuilt the carbs and accelerator pump.  They ran fine from April-September before teardown #2.

Any ideas would be great!
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Offline mrrch

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Re: Accelerator Pump Woes
« Reply #1 on: March 15, 2012, 12:34:20 PM »
An accelerator outlet is plugged so it has an airpocket maybe??
Did carb cleaner squirt out the outlets?
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Offline TwoTired

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Re: Accelerator Pump Woes
« Reply #2 on: March 15, 2012, 01:01:54 PM »
Either there is blockage between pump pressure source and outlet. 
Or, the check valve at the pump is allowing the fuel to get sucked back into the pump on de-stroke of the pump.
Another thing to check is that the diaphragm's "ears" have the same hole size as the what it mates with in the carb bowl or pump body (no allowance for restriction).
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Offline theofam

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Re: Accelerator Pump Woes
« Reply #3 on: March 16, 2012, 06:14:28 AM »
mrrch/TT, thanks for weighing in.

mrrch, yep, carb cleaner squirt out the inlet/outlet tubes as well as the accelerator pump nozzles.  It was forceful, too, not just dribbles.

TT, I had cleaned out the check valves and enlarged one of the diaphragm ears to match the larger hole when I rebuilt the accelerator pump last March/April.  So, I didn't pull the carbs again to check those.

However, I kept pumping the accelerator pump and it cleared up the issue by pulling fuel into the other tubes.  I just needed to be more patient!  Haven't heard that before.
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