superjet malfunctioning fuel valve? CARB FLOODING WITH FUEL???????

[AdamOntario]

hey guys,

my buddies ski, just put exhaust on it and if the fuel valve is in the on position it floods the carb and by that I mean you can see waterfall of fuel from the venturi with the flame arrestor of.

BUT when switched to reserve works fine, what gives? I have never seen this before, it looks like the jets are bypassed when in "on" position because it litteraly pours the gas into the carb throat.

thanks in advance
Adam

 

[douglee25]

Sounds impossible, or weird shall I say. Have you tried venting the tank with the gas cap? Is excessive pressure built up somehow?

Doug

 

[AdamOntario]

not the pressure in the tank, i "remembered" to do that,

what would cause A LOT of fuel pouring into the carb all together, I mean the jets would limit the fuel and the way it looked it literarly filled the throat of the carb with fuel to the venturi :bigeyes:

 

[Speedfreak]

Maybe your reserve valve doesn't work because if your needle valves are stuck open (that is the only way that fuel can flow) then your reserve is clogged since on and reserve both feed the carb from the same tube. Also check the air hole on the side of the carb to make sure it isn't clogged or the exhaust tube hasn't sealed it off some how.

Is this while it is runnig? If so did you mess with the carbs and forget the spring. The pop off being way too low will let fuel flood in also.

 

[Shrivel]

I had that happen to me once and it was the freakiest thing. My friend and I finally decided I had some blockage in my fuel line, so we blew it out and it worked fine after that. But not before fouling two plugs and really running very strangely for a little while.

It was wild taking off the flame arrestor and seeing the fuel just pouring down the carb throat even with the engine off.

 

[#ZERO]

If the fuel tank is exposed to direct sunlight for any period of time, on a hot day, excessive pressure will build and force some fuel through the carb venturi.

There is more pressure at the bottom of the fuel tank due to the weight of the fuel and this is why the problem goes away when switching the reserve fuel selector.

The next time this happens, slowly remove the gas cap and the problem should go away.

 

[superramjet]

needle stuck open or pop off spring to weak

 

[RiverRat]

needle stuck open or pop off spring to weak

I had this happen to me before. Especially if the carbs have been sittting for a while. I also had a set of carbs rebuilt at JSS and he forgot to install the screws that hold the plate over the jets. That prevented fuel from taking any give route and made fuel jusp pour out of the carb.

Also try to blow into the tank through the check valve vent (remove check valve. If fuel pours out of the carb you know a Needle is stuck open.

 

[AdamOntario]

thanks for the replies,

after taking the carb apart for the n-th time the problem went away, how I don't know since I cleaned the needle and seat each time and we always vent the engine compartment and the fuel tank before riding.

so now the setting up starts, right now its running with 140 main 120 pilot and 115 g spring + 1.5 seat, since I have not been on it yet :bigeyes: I can't say anything.

thanks,
Adam