96 xp running away

[Aftermath]

ok, first and foremost, thanks for having me here in seadooforum.com. this forum is awesome.

I recently replaced all of my oil and fuel lines and cleaned the carbs. once i got it all back together, it revs out of control and the usual choke, pulling the plug wires doesnt work. i have to choke and cover the carbs with a rag to slow it enough to kill it.

ive read all of the usual information posted here and checked everything ive read so far: tightened all fittings, checked pulse line, cant seem to find where air is getting in, carbs are super clean. low settings are 1&1/4 turns, highs on 1/4 turn.

I love this ski, had it since 99. Ive rebuilt the carbs many times since i first got it.

This is just a bummer.

any help is greatly appreciated,

Thanks :cheers::cheers:

 

[Bills86e]

Finding an air leak can be done with a can of carb cleaner with a straw. while engine is idle running gently spray the areas in suspect, like carb base gaskets and lower case seals, listen for an rpm increase.....you've found your leak.

 

[Aftermath]

Finding an air leak can be done with a can of carb cleaner with a straw. while engine is idle running gently spray the areas in suspect, like carb base gaskets and lower case seals, listen for an rpm increase.....you've found your leak.

No time to spray, runs away within 2 seconds

 

[Bills86e]

787/951's
Power Valve Engines run away because they are too lean for the amount of fuel being put into the motor. They get too much air, and not enough fuel. 951 engines will run away even without air leaks or lean condition. They will run away if the idle speed is set too high. You must have slack in the throttle cable at the idle position, and to set the on-hose idle speed to 2800 rpm, 1400 or so in the water.
If the engine continued to run without the electrical system (i.e. the lanyard was removed), the fuel has to be getting ignited from somewhere. Likely you have some carbon deposits in the combustion chamber that are getting hot enough to ignite the fuel. Carbon deposits are very common in two stroke engines. In addition to rebuilding the carbs, I'd suggest decarboning the engine using your favorite method. You'll likely need to replace the plugs afterward, but you should do that annually anyway.

1. Most common reason is out of the water and the idle set just 100 to 200 rpm too high. The confusing part to a 947 newby is that all other 2 stroke Sea doo engine models are set to 3000 rpm out of the water, but a 947 idles perfectly in the water when you set the idle speed at 27-2800 out of the water.

2. Allowing the head to get too hot becuasue it is running without water going through the motor when on the trailer.

3. And some of these next reasons could be a toss up in order, Replacing the carbs onto the engine for whatever reason and setting up the throttle cable adjustment too tight at the carb cable bracket, leaving the throttle plates slightly cracked open.

4. Clogged or partially clogged low speed jets.

5. Low speed adjusters are set too far in, not allowing enough fuel to pass at idle speed.

6. Water in the gas tank that ends up inside the carbs blocking fuel flow through the jets.

7. A poor job of keeping the carb base gaskets aligned when replacing the carbs onto the manifolds equals an air leak.

8. A pin hole or split in the plastic tubing that connects the engine case pressure fitting to the check valve in the rave valve pressure supply line, or a broken check valve in that same line. This allows air to go into the engine during up strokes, leaning out the mixture.

9. One stuck needle valve that will not open.

10. Rust inside the carbs, see #6.

11. A pin hole in the fuel pump pulse line.

12. I like Seafoam as a de-carbonizer

Bills86e

 

[Aftermath]

i do notice a large amount of oil coming from the exhaust or inpeller area leaking onto my driveway, not sure what thats about or if its related. there is still oil in the hull from where i changed the oil lines but not enough for the bilge pump to pick up

 

[Bills86e]

Its carb needle seats leaking, picking up soot in exhaust.

 

[Aftermath]

Its carb needle seats leaking, picking up soot in exhaust.

Is this causing it to run away? The carb kits have maybe 2 hours run time on them. How do I fix the problem? When I replaced the fuel lines and took the carbs apart, do you think I could have damaged the seats?

Thanks !

 

[Bills86e]

Remove carbs and recheck pop-off. Put sealant on the carb base gaskets. If you had the RV cover off, the large 0-ring should be replaced.

 

[Bills86e]

Open the gas cap. Do you have excessive gas tank pressure? If so clean or replace the check valve in expell line that exits under the rub rail.

 

[Aftermath]

i did check the vent line under going down the left side and there is blow through so im guessing that the vent is working. I also looked at a how to build your own pop off tester under the help tech section but there were no pictures and im not sure how that works. Do you have a link ? also the "RV" = rave valves? not had them out yet.

Thanks much for your help !!!!:bigear:

 

[Bills86e]

This type works very well on the Mikuni's:
http://www.watercraftsuperstore.net/PWC-Tools-Shop-Supplies/709SB021.html

 

[jhjesse]

X2 Bill
You are sucking air. If you just had the carbs off then it is most probably the gasket(s) leaking. Take the carbs back off and check the gaskets. Use sealer if you have to...anything to stop the air leak.

 

[Aftermath]

Replaced both gaskets. Nice and clean all surfaces. I dont think its leaking there but I will apply a thin layer of sealer to all sides and see.
Thanks!