Carbs flooding out from excess tank pressure??

Dave Geiger

Dave Geiger

I have a 07 SJ that seems to build a ton of tank pressure. It happens if it sits in the sun, sits in warm weather, every time you trailer or ride it. It’s enough to hear the pressure release (2-3x louder than my other SJs) when you take fuel cap off to add fuel. I’ve had it flood out (in 10mins sitting) to the point that it would take 45-60 sec of cranking to get it to fire up and then feather the throttle for 15-30 sec to get it to clean out. It’s also created enough pressure with selector in the off position to seep thru the brass t connections where my primer is put inline with zip ties on all fuel lines. Doesn’t matter how much gas is the tank either.

What I’m wondering is can a faulty one way valve on the tank cause this? Or is there a possible other problem. It does it with selector in both on and reserve position.

Stock internals
Bpipe
Ada head
Tauceti filters
Primer

Thanks for any input
 
Dave Geiger

Dave Geiger

Chase Musetti said:
Like you said, check one way valve. Pull it off and blow through it and make sure it’s installed properly.


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I’ve checked it, which it lets air in to keep tank from collapsing, and allows no air out, which I think is how it’s supposed to work?
 
Chase Musetti

Chase Musetti

Location
Winter Park
Dave Geiger said:
I’ve checked it, which it lets air in to keep tank from collapsing, and allows no air out, which I think is how it’s supposed to work?
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Yeah and it’s marked anyways pointing to the tank. I don’t have any other ski to compare to but here in FL my tank let’s off decent pressure when I take the cap off.


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D-Roc

D-Roc

I forgot!
Location
Dirty River Rider
The oem one way valves are actually 2 way. It works as a blow off after 7 psi which is low enough to not pop your n/s. That's why they cost more than cheap one way valves.


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Dave Geiger

Dave Geiger

TheBuzzard said:
if the carbs flood the motor, its always bad needle and seat. there is never going to be enough or excessive tank pressure to overcome pop off pressure. easy fix. replace the needles and seats. when a motor is flooded, always hold the throttle wide open until it starts and clears out.
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Normally I would agree, but I swapped complete motors in the ski this summer and it did the same thing to stock motor I put in the hull
 
Dave Geiger

Dave Geiger

TheBuzzard said:
I guess I've been doing it wrong all these years. instead of replacing needles and seats to diagnose the problem, I should have been just swapping motors.
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Lol.....I was testing the one with a pipe and head etc in a 13 hull to decide if I wanted to do mods to that motor also, just ended up showing me that it wasn’t carb related
 
WB1994

WB1994

Location
Amherst NH
If your tank builds preasure while the ski sits in the hot sun then the ONE way valve is working. Ive never heard of the one way valve having a secondary pop off to keep tank preasure down because the reason its one way is to keep fumes out of the bildge area so if the one way pops off to relieve preasure then its releasing fumes into the bildge which is what its designed not to do.

If your running stock flame arrestors then you have a high pop off so its harder for the tank preasure to pop the N/S but if your running aftermarket flame arrestors then the pop offs alot lower and could allow for flooding.

Most people run colored fuel lines which is the worst crap. That stuff even zip tied doesnt hold a good seal so those people experience less of a chance for tank preasure build up.

I run a dirtbike style one way valve and never get high tank preasure because of the way they work.
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
WB1994 said:
If your tank builds preasure while the ski sits in the hot sun then the ONE way valve is working. Ive never heard of the one way valve having a secondary pop off to keep tank preasure down because the reason its one way is to keep fumes out of the bildge area so if the one way pops off to relieve preasure then its releasing fumes into the bildge which is what its designed not to do.

If your running stock flame arrestors then you have a high pop off so its harder for the tank preasure to pop the N/S but if your running aftermarket flame arrestors then the pop offs alot lower and could allow for flooding.

Most people run colored fuel lines which is the worst crap. That stuff even zip tied doesnt hold a good seal so those people experience less of a chance for tank preasure build up.

I run a dirtbike style one way valve and never get high tank preasure because of the way they work.
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I have never had this issue except on my old SXR, It would spin the fuel cap. On my SJ never had an issue either. When I built my Freak I got some of the One Way's from Maniac and ever since then, I have seen some high pressures, few weeks ago felt like my engine was full of gas, it tried to run away the first few times I cranked it. Only think I could think of is it pumped into the cases........ This is also with brand new Blackjacks so I know the NS and not old.
Swapped out to an OEM to give a shot, but the warm weather looks to be gone so it will be next year before I can test out unless I just pull out in the yard and give it a scientific test. everything you posted makes 100% sense also........
 
WB1994

WB1994

Location
Amherst NH
This is the one I run and I never get a flooded motor. I swapped to a stock Kawi one and it flooded my motor with brand new carb with new N/S and everything else right up to the bottom of the carb. Crank case full.

Screenshot_20171106-122159.jpg
 
WB1994

WB1994

Location
Amherst NH
Big Kahuna said:
I have never had this issue except on my old SXR, It would spin the fuel cap. On my SJ never had an issue either. When I built my Freak I got some of the One Way's from Maniac and ever since then, I have seen some high pressures, few weeks ago felt like my engine was full of gas, it tried to run away the first few times I cranked it. Only think I could think of is it pumped into the cases........ This is also with brand new Blackjacks so I know the NS and not old.
Swapped out to an OEM to give a shot, but the warm weather looks to be gone so it will be next year before I can test out unless I just pull out in the yard and give it a scientific test. everything you posted makes 100% sense also........
Click to expand...


Running away means lean. If you start your ski and it wants to run away a bit at first give the primer a few blasts and it will calm right down. If its flooded on start up youll need to hold the throttle wide open.
 
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