This will be a dumb question. On my 140RX i am using a two line system the clunk line is going to the pump with a fuel filter in the line, and the vent line of the tank i have terminated in the side of the plane with a fuel dot. in other words the vent line is blocked off and the clunk line goes to the pump. is this correct or is the vent line supposed to stay open when it is running. read the instruction manual and am confused over it. maybe i am just over thinking the problem. anyways hoping to maiden flight the plane with it today so any replies would be nice.
Thanks
Dennis

The vent line must be open. I just use a tee in the main line, and run the vent straight out and open. No need for check valves and such.

It's really just that simple. Ya gotta love it [8D]

-Mike

Leave the vent line open! The OS pump on the rx140 uses crankcase pressure to move a diaphram in and out to pump the fuel. In short do not use a fuel dot. The vent must be open.

Thank you for the quick response

Yes, leave the vent line open. Be careful how you orient the vent line or it will siphon raw fuel out during flight. Does anyone have a fix to this other than using a YS check valve to let air into the tank?

Keith, I run a loop of tubing from the tank vent around to the back of the tank and then out the bottom of the plane. This prevent siphoning of fuel in the downlines.

I am ready to install the plumbing in my plane--I had thought about running the vent line to a brass tube with a 90* bend into the relative wind.

Does anybody see anything wrong with that idea?

I just stuck mine straight out the bottom through the pipe tunnel via a tube. No loops, no bends, no check valves, nada. Been doing it that way for about 5 years, I don't see where it even matters. But if it makes ya feel better, do some engineering [8D]

-Mike

I use a Fourmost products plastic check valve in place of the plug for the fuel dot on the vent line. They are color coded (1/2red - 1/2 white) so you have a quick visual check for correct installation.
-Will B.

Well the first two flights are completed. Never had anywhere near this much money in the air. so my knees were shaking so much i thought i was going to wee myself. did not think about using a check valve i think i have one kicking around maybe next weekend i will use it i will feel better than just leaving the vent hose flapping in the wind.

Hey Dennis Congrats on the Maiden. I remember flying my expensive full pattern plane, man was I nervous.

I loop the fuel line around the back of the tank too and just poke the vent straigt out the bottom up where I can see it, also keeps from spilling fuel when your carrying the plane around.

What plane are you flying?

This is how I did it http://www.rcuniverse.com/forum/m_28..._1/key_/tm.htm

Hello Everyone,


Well, I’m not running a OS 1.40 RX but a Webra 1.60.
I think the fuel pump works basically the same as the OS one.
I have an Over-flow on the side off my plane and a check-valve in site the cowl.
That is where it could get some air force trough.
Well this set-up I’m using for a bout 9 Month now.

I hope I was clear an off .

Here follows some pic, before I’ve flew it .
One off them( inside the cowl, the metal tube ) is for the fuel line and the other over the vent.
The over-flow is plug whit a fuel-dot.

Regards,

Danny Koolman
www.arubarcclub.com

Hi everyone ,

Here follow a link.

http://www.rcuniverse.com/forum/m_13...tm.htm#1391714

Regards,

Danny Koolman
www.arubarcclub.com

Brian it's a focus II. not so manly colors maroon pink and white. I had to return 30,000 empty pop bottles at a dime each in order to afford it. you gotta love michigan's bottle return law. Mostly the people at work found out what i was doing with the empties and started dropping them off at my toolbox every night. So all i had to do was go to the store about six times a month to return them for about a year to pay for everything ah who am i kidding maybe two years.
Brian are you flying in jasper in a couple weeks? i probably will not just a long drive it's about three hundred miles to indy plus the rest of the way to jasper. I should have spent the empties on a new used truck will try and hit the shootout in muncie this year though at least that is the plan.

Im planning to go to Jasper. Its a ways further south of Indy like you say. I just realized thats a couple weeks away, been anxious to get to a contest.

Sounds like you have a good setup I hope you enjoy it.

I'll see you at Muncie.

Be careful with the YS check valves I used one on my vent line off of a Webra 145 2 years ago. I started to have all kinds of problems with the engine and come to find out that the YS check valves wern't working very well. man can that cause engines to run erratic.
Good luck with your new plane Dennis. Your a good flyer and the Focus is going to help you alot. Mike

Thanks

.
.
Mike,

I like simplicity also, but the side of my plane had more fuel on it than I burned in flight. . . . My vent is a 90 degree bend into the wind. I may try the loop around the back trick. . .

You need a low pressure check valve.

The ones with a small coil spring and a ball work the best. If you can blow through it very easily, it will work just fine. A YS check valve is too hard to "initiate" and will fight the low rpm draw of the carb.

I don't use a check valve any more because if the tank heats up the fuel is forced into the engine through the pump. It then drips a lot through the carb lot or floods when the engine is started. I do use a filter on the vent line to prevent debris reaching the tank. The vent filter does catch crap because I regularly find dirt in my catch-bottle after filling the tank.

Regards,

Eric.

Eric so that's the reason I had problems with the YS check valve. I can assure you that it does cause problems with the idle. Do you have a link to the low pressure check valves you are refering to? Thanks, Mike

Well Dennis,

Sweet!!! The first couple of flights are always the hardest, it gets easier. I've got 9 on my Excelleron so far, and just got the CG set where I think I want it, I'll know later this week. I know, just like you, I've got a lot flying to do to get the plane right.

I'm glad to see you got it in the air, congrats!

Tell Aleta we said hi, and we'll see ya' at the Shootout.

Let's git 'er dun.

Ken

Hello everyone,

I’m using the YS check valve, and I don’t have any problem ( yet ) with the idle.
I’m using a MC carb tough, and don’t really know if it would make a deference.

And to prevent flooding the carb. (engine ) I bull the fuel dot of my over flow, and
remove the fuel line that is connected to the engine and plug it with a fuel dot.

I would also like to know where you could get one off those check valve.

Mike,
And what harm did the YS check valve do, only idle problems?


Regards,
Danny Koolman
www.arubarcclub.com

Danny the YS check valve makes the engine erratic because it needs a little more pressure. Try blowing thru one and you will be surprized by the resistence. I'm pretty sure it's an accident waiting to happen. I would rather not use anything that has potntial to fail like that. Mike

Hi Mike,

Could you describe the characteristic of the engine while idling?

Every month or so I make mine cowl clean and so I’ll check every thing out.
And every time I check the check valve also, but I didn’t (never) notice (or perhaps pay
much attention) to how much air flow “pressure” it need to open the Check valve.

And don’t know, if this is helping me or not; but the check valve is locked where the air
that the Prop produce go right true the cowl and in that spot where it is locked.

But really would like to learn more about this.


Regards,
Danny Koolman
www.arubarcclub.com