How to Rebuild Accelerator Pump

[natem1270]

Just picked up my second ski after having a ton of fun with my 95 SPX I fixed up this summer. New ski is a 99 GTI. For my first ski I followed Middymac’s carb rebuild thread and the ski has ran great ever since.

The issue I’m having here is the accelerator pump section of the carb rebuild thread is marked as to-do. I’ve reviewed the manual and I’ve found how to pressure test and lubricate the accelerator pump’s plunger and cam.

I’m looking for any tips/tricks or resources on how to rebuild this pump. Does the OEM Mikuni kit have any accelerator pump parts I should replace? Are there any settings on the pump I should be wary of or is that all done through the throttle cable adjustment?

 

[Pedec]

I am interested also. About to rebuild carb on my 97 xp with Accelerator pump.

 

[etemplet]

If the pump works leave it alone. Make sure the nozzles in the carb throat at spraying an equal amount of fuel when you test the pump. Inspect the hoses and make sure they are in good condition.

There are threads on the forum where members were looking for the diaphragm for the accelerator pump. I've fought a few of these and recommend leaving them alone of they are pumping.

 

[Pedec]

Ok will check to make sure accelerator pump is working before taking carbs off. If it is working will leave alone. I did order a OSD back to stock carb rebuild kit wit a diaphrgam for pump. With OSD kit do i use stock spring for pop off or one that comes in kit. Thanks.

 

[etemplet]

I test the pump with the carbs off the ski. I just install a feed line with a little bit if fuel and let the pump do its job. It is easier for me to see what is going on. I've had some real issues with the nozzels in the carb throats. Those are check valves so you need to make sure they hold a pound or so. They will relieve at about 3psi or something close to that. When I say I had trouble it was generally the 951 dual carbs. You can eliminate the accelerator pump and just install a larger low speed jet. Don't ask me what size though. Maybe up 5 from the old one. Good Luck !!

 

[Pedec]

Just tested carb and pump is working was squirting fuel on both carbs. Used my home made pop off tester made from bicycle shock pump and mag carb pops at 25 psi. Going to check pro carb tonight. Thanks for help. Can defiantly hear seat leaking the reason I took carbs off under pressure.

 

[etemplet]

I looked on the site I goto for carb information and it says the range for pop-off is 22-37psi. You can check the manual on the desired pop-off. I find that Seadoo engines like the higher end of the pop-off spectrum. When you are on the low end (like 25psi) the carbs are on the rich side and are not as snappy as they can be. With the proper seat and springs you should be in the preferred range. If I was guessing I'd want to run about 33psi pop-off but that is just a guess. I once chased Pop-Settings on 2 Carb GTXs skis from 23 -37psi. I pulled the carbs and reset them 5 times starting at 23psi. When I got to 37psi the skis performed so much better. With that in mind I always choose the upper end but not the very top ofthe range. As I said, the proper parts should land you right in the sweet spot. Good Luck.

 

[Pedec]

Thanks.

 

[Pedec]

So I took apart my mag carb and everything looked great actually like new and is genuine mikinuni kit in it. I did try a pop off test before taking it apart and was 36 psi but was kinda slipping on way up and would lose pressure fast after pop. Notice when I took needle out some very very small black balls coming off needle. Took rest of carb apart and everything is like new so blew out stuff with brake clean. Decided to put back together and try pop off again. It pops at 37psi drops to 28psi and maybe drop the width of the needle in 5 mins. After bleeding everything off and putting 12 psi on carb it holds solid for a hour. So I am wondering if I should just run it. Maybe take apart PTO carb also and just clean up needle and seat and test also. The ski ran good before just if it sat for more than 3 mins after running it would need full throttle to start and a bit of cranking like it was flooded. I think it was just a litte dirt in needle. Thanks for any help. I just ordered my back to stock OSD kit so will not have it for couple weeks not that it matters to cold to ride it now.

 

[etemplet]

I'd replace the needles. If you look at them under a magnifying glass you'll see a ridge. that stops them from sealing properly. With new needles iff up pop at say 37psi they will often reset and not leak at the range where yours is resetting. Often about 30psi they are pretty tight. I alway spray the WD 40 and look for any bubbles around the seat area. That's where your gas leaks though when the ski is sitting and that causes flooding and makes it difficult to start. Then pressure the carb up to 15 or 20 psi and spray a soap mixture and look for bubbles. Good Luck !!

 

[Pedec]

Ok thanks

 

[POPPS]

Finding the orange umbrella check valve has been impossibe..it does NOT come with the mikuni kit.

 

[Pedec]

Took needle and seat out and put needle under magnifying glass and sure enough there a ring around it. happen to have new o-ring for seat and put it and tested again. Pop at 37psi stop at 29psi but bubbles coming up around needle so it needs a new needle still.

 

[etemplet]

You got it. That's what I find. I buy the needles and seat together but they are not cheap.... about $17 per carb but it's a "once and done." Good Luck !!