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Bogging and won't make top speed.... Need some help!

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So my bogging issue ...

When hooked to the hose it runs amazing!

When I get it in the water, It idles great, when you squeeze the throttle at about 1/4 it starts to bog and sound alike it's running out of fuel. If you pump the throttle I can get it rev a little bit but still sounds like it's running out of fuel. If I pump the choke slowly when I'm pumping the throttle I can get it to run WOT. That is holding the choke open about 1/4-1/2. If I let off the choke it Boggs right down and wants to die.
 
I'm going to get all new fuel lines today and start replacing. Also, the check values ... Where can I get those.
 
Another thing to help troubleshoot this:
Turn the low speed and o 2&1/2 turns out.
If that helps, your dealing with the low speed circuit still.

Think of it this way. The only way your engine gets fuel is negative pressure and positive pressure produced by the engine.
This will allow the pump to prime the needle valve and assist in pushing it off the seat when there is a demand for fuel.

What creates this demand is negative pressure in the intake. By sucking fuel e out of the pilot circuit your creating a negative pressure on one side of the diaphram which pulls it in and that pushes on the lever that opens the fuel valve. Fuel pressure from the pump helps this along by forcing it off the seat a bit and supplying fuel to the chamber which pushes the diagram back and closes the fuel supply off again. This is metering. The pop off pressure affects this part of it. As in more pop off pressure means you need a stronger suction to get the fuel moving.


So if your pilot circuit is still partially plugged, you can't pull the diaphram down hard enough so you get a bogg until the main jet starts to flow which in that case has more than enough suction to open the fuel valve and give you a good supply of fuel all the time. Pulling the choke has the same effect. It creates a suction so strong that your going to get fuel no matter what.

A weak fuel pump can also do this. The check valves do wear out and it behaves like a heart murmur. Basically less pressure because the pressure isn't holding, so the fuel is moving one way and then moving back instead of building up pressure and then not looking pressure until there is a demand for fuel.


By opening the low speed to 2,1/2 your making the demand for fuel stronger and if this helps we are still dealing with a supply issue.

Those check valves should have been in the carb kit.
 
OK, so when it bogs down, if you simply go to full throttle (all the way) it will die or will it jump instantly? From what I read it will die. But if you "pump" the throttle several times, it will gradually get to speed?

And pulling the choke knob helps, right?

Benji.
 
I read it as throttle only causes bogging no matter if he's pumping the throttle or not but at first it does help because he'using up the fuel in the accell pump.
And holding partial choke means throttle now works properly but only works with manipulation of choke and throttle at the same time.
 
I'm just gonna keep replacing stuff I guess ... Gonna check tank pressure today too, cause I didn't hear a hiss when I took off the cap.
 
Here is my experience.

Rotary valve: the people who replaced my engine didn't align the rotary valve properly (yes, a Sea-Doo dealer...). Result was (1) that the ski was not starting very well, (2) that it would accelerate up to 15-20 mph and then wanted to die. If I try to go to full throttle it would die suddenly but if I pump the throttle gently, it would start gaining some speed. Dealer thought it was the carb so they rebuilt it and screwed it. When I got it back, it was working even worse until they realized that the rotary valve was not timed properly. Didn't try to pull the choke at this point.

Carb: so with the rotary valve fixed, now the ski would have the second issue. It would (1) start very well, (2) would accelerate just fine with going to idle to WOT and (3) if I would accelerate gradually, it would get stuck around 15-20 mph and as I keep on applying more throttle, it would jump to 30 mph. There was simply no way for me to cruise at 25. It was either 20 or 30. We tried ajusting the low and high screws without any luck and they told me it was because of the rebuilt engine... I also tried playing with the choke and it would make the ski run better but that was obviously not the solution. I did not accept that answer and ordered a new carb from OSD parts and the issue went away completely. Somehow, while trying to rebuild the carb, they replaced spring or jet with the one from the kit which was/were obviously not the right ones.

Hard to say what your problem is but it could be one of the two if symptoms are identical to my ski.

Benji.
 
Hey, what's the back story on this anyway?

Did it just start acting up one day? Was there anything that caught your attention before this issue started ?
 
Yeah, rotary valve will not start acting out of the blue (if it start acting, it will be a much more serious issue IMO), neither the carb (meaning the wrong parts). Someone had to try to adjust them or replace them.

Benji.
 
do t really know what the back history is. I got it the guy told me that it wouldn't run. And the wife liked the colors....
 
Well now that's something interesting. It could be exactly like Benji saying and the rotary valve is not timed correctly.
There are only two ways that that can happen. One way is if the rotary valve gear stripped. The other is if the person that installed it installed it wrong.

And one more thing not to rule out is ignition timing. I have seen several of these 717 engines stripped the Woodruff key on the flywheel and that causes the ignition timing to be retarded. But in most cases when I've seen that the machine will still start and run good but it will stop making power at half throttle. In other words it would just run 5-10 miles an hour barely on plane and then stop revving any higher.
The ignition timing doesn't describe what's happening to yours but it's just good information to know.

If the rotary valve timing is off that could affect the vacuum signal going to the carb as in it's not getting enough when it needs it and then running lean unless you give it enough restriction with the choke.
 
Then I seriously think it is one or the other. Sounds so much like mine last year. It sucked so much with bad timing. It was even worse than a bad carb rebuild.

Benji.
 
Well, it is either: replace the carb or check rotary valve. At this point, I would start with the rotary valve. Checking rotary valve will take you 2-3 hours of your time and if nothing is stripped and it was just bad alignment, then you will know right away. Once you open the cover you will find the rotary "disk" and will have to inspect it for groove or extreme wear (mine had a small dent in it). This is where my knowledge ends. ;) Some people on this forum will be more skilled at telling you if the valve and cover are alright (post some pictures).

Like I said, if you have to "pump" the throttle to have the ski go to WOT, it resembles more a timing issue.

Benji.
 
Some experts can do it by eye. I was told that the real tool is about a few hundred bucks. You can order it from a BRP dealer I believe. I wanted to buy that tool myself as well because my ski may not be aligned dead on as well (it was done by eye by a really really good mechanics).

Benji.
 
Rotary is clean as a whistle, i aligned it by eye, it was really close but I moved it a few degrees. I found an article about lining it up
 
To align the rotary valve you set the MAG cylinder to Top Dead Center. Then you have to align the valve with a degree wheel per the manual. You can print the degree wheel out on paper and cut it out so there is nothing to buy. It can't be aligned "by eye". Those pointers on the case are not alignment marks.
 
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