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Engine basics => Engine set up tips => Topic started by: frank mccune on June 27, 2017, 06:57:14 PM
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Hello All:
How far should the uniflow tube be from the feed tube in a metal tank that has a wedge shape on the outside surface?
I have a tank that has the two tubes 1/4" apart and I get too many bubbles in the fuel line for the engine to run properly.
Suggestions and or comments?
Tia,
Frank McCune
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are you pressurizing the uniflow tube?
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Hello Randy:
No, I am not running any form of pressure to the tank.
Thanks for the prompt reply,
Frank McCune
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Hello All:
How far should the uniflow tube be from the feed tube in a metal tank that has a wedge shape on the outside surface?
I have a tank that has the two tubes 1/4" apart and I get too many bubbles in the fuel line for the engine to run properly.
Mine are usually within 1/8" and pretty much never have that issue.
Brett
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You are always going to get a few bubbles in the fuel line no matter how it is plumbed, I think you may have a problem elsewhere. If it's an older tank, the uniflow or pick up tube may be cracked. Your spray bar may have some crud in it and causing issues. one reason I always use a in line filter is because I think it give the crank case vacuum something to draw against and gives smoother flow from that point to the spray bar. You might want to try muffler pressure for a flight or three to see what happens if nothing else works, and cant the back end of the tank out if at all possible. Justa bit can help with fuel pick up, especially at the end of an engine run.
Type at you later,
Dan McEntee
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Hello Randy:
No, I am not running any form of pressure to the tank.
Thanks for the prompt reply,
Frank McCune
my tanks are all setup with 3/16 difference, no problems ever, try a fuel filter like Sullivan's crap trap , no bubbles can pass it, then look for loose items and.or vibration
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Hello All:
This problem came on very quickly leading me to think that it is a problem with the tank. Everything is tight and I am using a fuel filter which permits bubbles to pass through and onto the nva. This setup worked perfectly until I got to a contest Sunday. I have flown this airplane, engine, prop and tank without a problem for a long time. I will switch t a new tank and see if it cures the problem.
Thanks for all of the help,
Frank McCune
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This problem came on very quickly leading me to think that it is a problem with the tank. Everything is tight and I am using a fuel filter which permits bubbles to pass through and onto the nva. This setup worked perfectly until I got to a contest Sunday. I have flown this airplane, engine, prop and tank without a problem for a long time. I will switch t a new tank and see if it cures the problem.
Check your tubing, too. Silicone's softer than tin, after all.
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Hi Tim:
Thanks for the reply! I replaced all of the fuel line and checked the replacement via air pressure being applied to the fuel line and tank, no leaks.
I will test the "new" tank set up today and get back to you.
Stay well.
Frank MCune
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Hi Tim:
Thanks for the reply! I replaced all of the fuel line and checked the replacement via air pressure being applied to the fuel line and tank, no leaks.
I will test the "new" tank set up today and get back to you.
Stay well.
Frank MCune
Hi Frank
A pressure test do not work if you have a crack in the hard fuel tubing inside the tank
either in the feed line or pressure line, both will cause the problem you are asking about
Randy