Freestyle fuel getting pushed threw the primer?

[Tyler Zane]

i have had a bogging issue that i resolved by unhooking my primer. i first noticed it when i popped the hood and saw fuel moving threw my primer line. pulled the flame arrestor off and it was just flowing in my carbs. take the gas cap off and it stops. this just became an issue when i replaced my gas cap o ring. im wondering if im building to much pressure...

carbs run straight off of the reserve pickup and the primer run straight off of the "on" pickup. is it normal for your fuel lines to have to re prime at the start of the day? i get really high revs right off the bat until the fuel lines work all the air out. should i run a loop in my carb line?

 

[FlightPlanDan]

Where does your primer take it's fuel from?
The "in" to your carbs? or the return line?.

There are different schools of thought.

 

[Tyler Zane]

Where does your primer take it's fuel from?
The "in" to your carbs? or the return line?.

There are different schools of thought.

it has its own pickup. bad idea?

 

[RyanO]

It needs to run off of a T on your carb lines other wise when the tank pressurizes, fuel will be forced through the line.

 

[Dustin Mustangs]

Wouldn't the carb lines be pressurized as well?

 

[FlightRisk]

Wouldn't the carb lines be pressurized as well?

Yes. I asked about this in another thread concerning my one way valve on the tank. An OEM vent should let pressure out somewhere around 5psi, but after cutting one open I don't know if I believe that. I kept having an issue with the low end filling with fuel when the gas tank was pressurized.

I fixed my problem by t'ing the vent line to another one way valve to let pressure out, running that through a water seperator then out the pole.

 

[tor*p*do]

the tank vent is a check valve- flows only one way
it allows air IN to avoid the tank collapsing when fuel is removed
it does not "open" at any pressure
you WANT to build pressure in the tank

bulb or plunger primer?

 

[FlightRisk]

http://www.x-h2o.com/threads/90332-Gas-Tank-Vent

Seems to be some conflicting opinions on the one way valve.


Why would you want to build pressure in the tank?

 

[tom21]

cause under suction no fuel would flow to carbs. your primer may be bad and if I am not mistaken running off the return will not work as it just dumps into the tank and does not have a tube that goes down into the fuel. the directions say to put it on the reserve line. so maybe if you simply switch to reserve when not running it will not pressurize past the primer? (yours is installed on the "on" hose?)

 

[engineman44]

wow i hooked mine up on the in line before the petcock may switch mine too

 

[tor*p*do]

http://www.x-h2o.com/threads/90332-Gas-Tank-Vent
Seems to be some conflicting opinions on the one way valve.
Why would you want to build pressure in the tank?

you know what opinions are like, everyone has one . . . . .
stock SJ builds pressure in the tank, hence the pssst when you loosen the tank
this helps to deliver fuel
new SJ check valve lets air into the tank and not out
only thing it does is prevent tank from collapsing when fuel is removed

 

[Proformance1]

IMO, the reason i installed primer t in return line is because it is supposedly under less pressure than feed and if it fails which, IMO they do, it will not suck air into carbs. Could and will it make priming on a ski that ahs not been ran in a while difficult, yes, i believe it does. but if you install T in the lowest part of the return line it may hold enough fueel to start it. once you spin the motor a bit it fills the return line with fuel and you are set to prime it. AGAIN, IMO

 

[BruceSki]

If I know a ski has been sitting for a while, I will blow air through the tank vent to pressurize the tank. It makes it easier to get fuel to the carbs and get it started. Make sure the tank vent is on the right way also.

 

[FlightRisk]

cause under suction no fuel would flow to carbs. your primer may be bad and if I am not mistaken running off the return will not work as it just dumps into the tank and does not have a tube that goes down into the fuel. the directions say to put it on the reserve line. so maybe if you simply switch to reserve when not running it will not pressurize past the primer? (yours is installed on the "on" hose?)

Under suction no fuel would flow. Neutral pressure in the tank is the idea behind the one way valve correct? This allows air in, eliminating negative pressure in the tank created by the carbs drawing fuel.

He's talking about positive pressure.

you know what opinions are like, everyone has one . . . . .

Yup, we all post em here! Lol.

 

[aramis]

The one-way valve is NOT designed to leak air out at 5psi or any other pressure, according to the shop manual. It is a ONE-WAY valve.

Pressure builds in the tank BECAUSE fuel is not flowing. It's an incorrect assumption to extrapolate that to say that pressure NEEDS to build to enable fuel flow. Pressure builds in the tank due to PV=nRT (with a fixed volume) and the vapor pressure of gas.

Suction is NEVER created in a proper setup, since make-up air is allowed into the tank through the one-way valve and the fuel return is bringing gas back in. Lack of suction does not necessarily equal positive pressure.

This is a very simple, well engineered system that everyone makes more complicated than it is.

 

[Freakrider]

I bought a ski that had the primer tee'd into the return line and it did pull fuel out of the return line/carb fine but as the primer got older it began to have a bit of trouble pulling fuel...I switched the same used primer to the reserve line and it worked good again until it wore out...

If there is air in the primer line because the primer is worn and does not hold a good seal, YOU CAN RUN LEAN on that fuel circuit such as when switched to the reserve line...some guys don't run primers for this reason but I like them for convenience and to avoid lean start ups...plus a good primer will kill a just in case run away ski...

 

[SXIPro]

IMO, the reason i installed primer t in return line is because it is supposedly under less pressure than feed and if it fails which, IMO they do, it will not suck air into carbs. Could and will it make priming on a ski that ahs not been ran in a while difficult, yes, i believe it does. but if you install T in the lowest part of the return line it may hold enough fueel to start it. once you spin the motor a bit it fills the return line with fuel and you are set to prime it. AGAIN, IMO

Agree 100% return line is the safest route to go. And yes, if yoy have the T in the lowest spot, and more importantly have well tuned carbs, it works fine even after long periods of time. Mine works fine after sitting six months set up like this.

 

[Tyler Zane]

plunger primer, near new.

carbs run on the "reserve" pickup on the tank. the "on" pick up was the primer only.

i have no petcock.

the pressure in the tank was pushing fuel threw the primer. this is not a default of the primer. i still get lean and high revs till the lines clear of air, with or without the primer.

do your lines stay full of fuel between rides?

 

[BruceSki]

That depends on what carbs you run... I think certain aftermarket carbs have a tendency to drain between rides

 

[motobehrens]

I've had a new primer bulb that allowed fuel to get pushed through. It was just a faulty primer. I never had issues with High revs right after startup though. I use the reserve pickup as the dedicated line for my primer. That may be two separate issues. Try a good primer and see what happens.