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Old Apr 12, 2007, 01:41 PM
V10
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Joined Jan 2007
19 Posts
Help!
Trouble fueling my PTS mustang

Hey folks, I just picked up a hangar9 PTS mustang and it's my first nitro plane (been flying electrics). I'm trying to get the tank fueled up and having problems. I'm using a hand pump and connecting it to the green fuel line as per instructions. It tells me that the tank is full when fuel squirts out of the red line(a line that attaches to the muffler). Problem is that when fuel starts going into the green fuel line, it almost immediately starts coming out of the red tube. If I remove the wings and look at the tank, it only has about 1/8 of a fill. Tilting the plane vertically, i was able to get it to about 1/4 of a tank but alot of fuel wasted in spillage.

Can someone tell me what I'm doing wrong, I'm sure it's a dumb newbie issue. Also when i got it 1/4 full I started the engine, and noticed when i gas it up, alot of fuel sprays back from the muffler through the red line, is that normal?


-Steve
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Old Apr 12, 2007, 01:51 PM
E.J. Murphy
Omaha, NE
Joined Oct 2005
141 Posts
Just guessing, but it sounds like you have one problem and one normal situation.

As far as filling the tank, you may need to double check the hose connections to your tank. You may have the pressure line (the one going to the muffler), connected to the fill tube of the tank stopper. Or, the tubes in the stopper are turned the wrong way.

When you say gas it up, do you mean give it throttle while it's running?
If so, what you see coming out of the tube at the muffler is actually unburned oil being blown passed the nipple.

HTH,
E J
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Old Apr 12, 2007, 02:02 PM
V10
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Joined Jan 2007
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Thanks EJ, yeah that's what I meant about giving throttle. I'll have to try to check where the hoses are going to, the fuselage was preassembled by hangar 9 and it's hard to see where the lines are connecting at the tank.

If I'm understanding what your saying, then should I just switch the lines, the one attached to the muffler, put that on the fuel intake? I think then that worst case scenerio, the engine would not start right?
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Old Apr 12, 2007, 02:50 PM
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mxerman's Avatar
USA, AL, Montgomery
Joined Feb 2006
304 Posts
Sure sounds like the fuel tank has the lines reversed. Try filling through the other line and if the tank fills up just reverse them to your engine/muffler. The oil coming out the muffler while running is normal. Good luck, mxerman
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Old Apr 12, 2007, 02:51 PM
Registered User
Letchworth, Great Britain (UK)
Joined Jul 2004
11,119 Posts
Sounds like the tank, or just the tank stopper if it's that kind of tank, may be installed the wrong way up. The fill line and the pressure line should both go to the top of the tank -- if they're at the bottom, fuel instead of air will come out the pressure line as soon as the fuel level reaches the pipe.
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Old Apr 12, 2007, 03:43 PM
V10
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Joined Jan 2007
19 Posts
abenn, you might be on to something, b/c when I did get the spray, it was ALOT, and I could see it coming from the tube that goes into the muffler, and there was not good flow to the one going to the engine. I'm at work now, but will put everyone's advice to work tomorrow morning.

I really appreciate the help folks!
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Last edited by V10; Apr 12, 2007 at 03:49 PM.
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Old Apr 12, 2007, 11:49 PM
V10
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Joined Jan 2007
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Also, would like to ask a mechanical question, What's the purpose of the "pressure" line? Is it there just to keep a vacuum from forming inside the gas tank when the engine draws fuel, or is there another purpose for it?
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Old Apr 13, 2007, 02:39 AM
Registered User
Letchworth, Great Britain (UK)
Joined Jul 2004
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The pressure line actually pressurises the tank a little, using the pressure from the silencer. It's not a great amount, but it helps make the fuel feed more constant when the tank is in all sorts of attitudes during flight.

Once the engine's running it doesn't matter whether its outlet is below or above the fuel level, but during fuelling it needs to be above the fuel to allow air to escape from the tank.

Edit: P.S. You can test the theory about tank inversion by holding the plane inverted while fuelling, to see if any fuel squirts out then
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Last edited by abenn; Apr 13, 2007 at 04:51 AM. Reason: More info.
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Old Apr 13, 2007, 08:53 AM
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United States, TX, Round Rock
Joined Dec 2004
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The stock tank that comes with the plane is preassembled. It has only 2 lines - one has a piece of tubing and a clunk at the end that always falls to the bottom of the tank no matter what the plane orientation is, the second line is a piece of tubing bent to the top of the tank when the plane is upright. The first line connects to the carb/needle, the second - to the muffler nipple.

In this particular case there are 2 possible causes:

1. The tank is mounted upside down - the vent/muffler pressure tubing in this case is at the tank bottom when the plane is upright. As soon as you start fueling, the fuel level reaches the vent line and starts running out of the tank as the remaining air gets trapped inside the tank. Solution: Remove the tank and put it back so the end of the vent line is at the top of the tank WHEN THE PLANE IS UPRIGHT!. Keep in mind that when you work on the tank installation, the fuse is upside down, so the vent during the tank installation should be pointed down. I usually draw an arrow on the back of the tank pointing to the top of the tank. When installing the tank I make sure that the arrow points in the right direction.

2. The carb (clunk) and muffler (vent) lines are swapped. In this case the muffler is connected to the clunk and you're fueling trough the vent. As soon as you start fueling the plane, the fuel reaches the clunk and starts running out as air is trapped inside the tank. Solution: Swap the two lines at the muffler and needle ends.

It's also possible that BOTH #1 and #2 are in effect - then you'll need to reinstall the carb in the proper orientation AND swap the lines.

As far as the unburnt fuel coming out of the muffler when the engine is running - it is normal, although all engines come from the factory set up very rich - you'll need to lean it some, but always keep it on the rich side of the needle. Read the sticky at the top of the Engines forum. Even better - ask someone with engine experience to adjust it for you in the beginning - until you learn to do it by yourself.

Ivan
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Old Apr 13, 2007, 03:09 PM
V10
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Problem Solved!!!!

Thanks for the input, you guys were head on, I took it to my hobby shop today since I wasn't comfortable at this point with removing the engine (found necessary to check the fuel tank). They found that the bent tubing (whatever its called) was installed upside down by hangar9. They flipped it over, put it back together and it fuels problem free now!

And even better, I met a very experienced flyer at the hobby shop (20+years) who offered to coach me while hooked up to his radio for my first nitro flight!
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Old Apr 13, 2007, 03:23 PM
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United States, TX, Round Rock
Joined Dec 2004
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Glad you had figured it out.

BTW, our engines are not "nitro". They are glow or alcohol engines. They need methanol (methyl alcohol) and a glow plug in order to run. Nitromethane (also called just "nitro") is an additive which improves engine starting and adds a tad of power, but is not absolutely needed. Many guys use fuels with 0% nitromethane without any trouble.

Ivan
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Old Apr 13, 2007, 03:31 PM
V10
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Ah ok, thanks clearing that up, I just figured it was a broad term for all fuel powered engines.
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Old Apr 13, 2007, 03:48 PM
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Banjul
Joined Jan 2001
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A little bit more on the topic . . .

There are three "fuels' for RC flight . . . glow, gasoline, and diesal.
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Old Apr 14, 2007, 02:49 AM
Registered User
Letchworth, Great Britain (UK)
Joined Jul 2004
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... and electricity.
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Old Apr 14, 2007, 07:50 AM
God is good
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Banjul
Joined Jan 2001
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abenn, the key word here is "fuel". Now you're just confusing him!
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