Accelerator pump

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JJinSC

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Ok, I have been on vacation this week and mostly trying to enjoy the Seadoo. I've been successful and the weather has been perfect here. I took the ski out of the water one morning just to check some thing's for a couple issues I am having. One is difficulty keeping it running on warm restarts after sitting for at least 15-20 minutes. I leak checked the carbs and they are not leaking. I have some more things to check on for that latter. The other issue - and they could be related -is a bog/hesitation from idle. So while I had it out, I checked the a-pump nozzles to make sure they are giving good squirts. I checked this extensively and the nozzles appear to be clear and open. The only thing is the a-pump seems to be iffy on whether it has a prime or not. It seems to come and go. I have checked the inline check valve after the pump for proper functioning and it is. Is there another check valve anywhere else? Can anyone list issues that may cause the a-pump to occasionally not pump? I know several of the most obvious things but most of these have already been checked. I am interested in other things in the carbs themselves that could be starving the a-pump from fuel.

Would a small pin hole in the a-pump diaphragm cause this symptom?


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Still would like input to the previous questions, but I have been doing some extensive reading about accelerator pump issues. I just replaced my a-pump fuel lines about two weeks ago trying to resolve this ever allusive issue of bogging/ hesitation off of idle. Before, it was a bog because the MAG carb nozzle kept getting clogged between seasons. Now after cleaning and changing the small lines it is a hesitation that will clear on its own if I either keep pressing throttle further (clears quicker) or if I hold it right at the hesitation spot (slower clearing and going). When I was changing the lines I remember reading about this little brass recharge metering jet. So I checked my lines (output) and did not find it. Then I read an article today that clearly stated it was in the input line and not the output line. Fortunately, I saved my old lines and came back to them to look. Lo and behold look what I found. (See below). Could this being left out of the new lines be causing my symptom?


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Yes. That's a restrictor, and without it... you are pumping in too much fuel.

If you had a hole in the diaphragm... you would have a leak on the pump cover, since there is a hole to let it breath.
 
Yes. That's a restrictor, and without it... you are pumping in too much fuel.

If you had a hole in the diaphragm... you would have a leak on the pump cover, since there is a hole to let it breath.

So if I understand you, you are saying this could be my hesitation problem and I most likely do not have a hole in the diaphragm or it would have leaked down in my test the other day?


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You defiantly need that restrictor. If the diaphragm had a hole it probably wouldn't squirt out the nozzles.
 
Been doing some research on this little brass restricter. It appears to be the result of service bulletin 99-03w. I assume this service bulletin is from mikuni as I have seen it referenced on other brand skis with accelerator pumps as well. Do a google search on that service bulletin number and you will find the exact wording of the bulletin. Unfortunately, based on what I have read I do not think this is responsible for my hesitation. It appears to be a fix for stalling during a deceleration and causing lose of steering. I do not experience this issue and now have doubts replacing this piece back in the hose ( which I still plan to do) will have any effect on my hesitation issue.


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