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How to vent the fuel tank


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I have just bought one of these to fit to my paramotor.

http://www.kkckartshop.co.uk/pc/KG-9-5L ... 4p1117.htm

the picture on their web sit is not very clear, but I will try to explain.

On the top there is the following.

1. The filler cap

2. A molded plastic pipe that you could connect fuel pipe to but it is closed off (you would have to drill it)

3. A Screw on cap with a brass fuel fixing (on the inside there is a length of tubing and a weighted pick up)

4. A screw on cap with a brass fuel fixing (nothing attached on the inside) - Assumed vent

I assume that the vented fixing is left open to atmosphere in normal use so as not to create a vacume.

But how do you stop fuel leaking out when traveling. My thoughts \ questions.

1. Can you get a one way valve to go in the place of the vent?

2. If I put a bit of tube betwwen the open vent and the closed vent when travelling and then remove it for flying.

3. Can you get a replacment filler cap that is vented and just close off the other vents.

Any other suggestions?

Thanks

I have just found a different tank but it is a better picture ( this one does not have the plastic vent that is closed off)

http://www.kkckartshop.co.uk/pc/R-R-8lt ... 4p1079.htm

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Thanks very much. I have ordered one in orange to match my frame.

Coluld not really justify spending more on the cap than the tank.

just for your info....the cap that they sell on their website which i presume fits the tank..

is a vented cap....same as the parajet one by the looks of it..

http://www.kkckartshop.co.uk/pc/CAP-FOR-PETROL-TANK-NEW-TYPE--214-10p491.htm

but the orange vent would look soooooooooo much better!! lol

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Hi guys,

I may be about to really display my mechanical ignorance here! Why does the tank need venting? Is it to stop a vacuum building up?

Cheers,

Tj.

put your mouth round a glass milk bottle and see how much you can drink without letting air in! lol

but in short yes....as the fuel comes out it needs to replace its volume with air, otherwise a vacuum occurs.

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  • 3 weeks later...

I thought I had this sussed I ordered one of the valves that was recomended and it des not work exactly as expected.

The vent is indeed a one way valve. i.e if you suck through it,it allows air in and if you try to blow through it the valve closes and stops any air getting out.

When the engine is running all is ok.

But the problem is that although it stops air going back it does not stop fuel going back. So if you lay the motor down in the car it leaks fuel everywhere.

Any other suggestions?

What I really want is a valve that allows air in but not let fuel out.

Argggghhhh.

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What you have to remember is that the fuel will expand in the car as it warms up and gets shaken about.

The vent on mine goes from the top front of the tank back around the tank (so it will not come out when I lean forward to get up) then back to the front and up.

So which ever way I lie the paramotor down the fuel cannot get out the end of the breather(fumes will yes but no fuel.

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I thought I had this sussed I ordered one of the valves that was recomended and it des not work exactly as expected.

The vent is indeed a one way valve. i.e if you suck through it,it allows air in and if you try to blow through it the valve closes and stops any air getting out.

When the engine is running all is ok.

But the problem is that although it stops air going back it does not stop fuel going back. So if you lay the motor down in the car it leaks fuel everywhere.

Any other suggestions?

What I really want is a valve that allows air in but not let fuel out.

Argggghhhh.

im probably stating the obvious here.....but why not carry 2 caps....a solid one for transport, and the vented one for flight....its not exactly a chore to change caps...as long as you include it in your pre-flight checklist.

:D

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