newflier1

My Feedback: (15)

Ihave an O.S. 55AX engine mounted inverted in a Phoenix Models Tucano. The carb on the engine is about at the center line of the tank. I am getting a siphoning effect when Itry to start the engine and fuel just drips out of the carb and the engine becomes hydro-locked. Someone told me to try and make a 'fuel trap' by loopiong some fuel tubing and to make the loop go to the top of the cowl. I tried that and the engine starts, but as soon as it stops, the siphoning effect starts and the enginehydro-locks. Does anyone have a soluiton for this problme? Is the last resort a Perry Pump?

Gray Beard

My Feedback: (-1)

Try lowering the fuel tank and see what happens. Inverted two strokes I set the tank up about 1/8 to 3/16 low. The center line of the tank that much lower then the center of the neddle valve. That is my starting point but I sometimes have to move the tank around a little to get it correct.

JohnBuckner

My Feedback: (1)

Indeed lowering the fuel tanks level in relationship to the spray bar is a must if you are to enjoy the installation. It is the spraybar or jet within the carburator that must have the proper height relationship with the fuel tank.

John

newflier1

My Feedback: (15)

I would have lowered the fuel tank if I could, but I can not. It is in a location that they designed for the tank - moving it is not an option. Ineed a way to keep the fuel from getting a siphoning effect.

JohnBuckner

My Feedback: (1)

In cases like this because of the poorly thought out design I either pull out the dremel tool and lower the fuel tank doing whats neccessary or change the engine mount to a sideways mount and this will usually raise the carburator sufficiently to cure the problem.

Some suggest always starting with the airplane upside down which may work but this is no solution and the carb will be loaded every time you are ready to start and the plug will have to be removed and engine cleared each time. In addition its clumsy and perhaps dangerous especially with airplanes using landing gear.

Another procedure and I have used this many times with some types of racers but do not reccomend this either as you will soon get sick of it.

That involves installing hemostats on the tank/carb line immediately after fueling and removing the hemostat just before starting or having someone remove them only after hitting the starter.

None of these methods are very desirable after a while or the fuel line loop thing just does not work dependent on how you or your helpers handle the airplane. If you or they carry the airplane even for a moment nose down any at all, a syphon can and will start flooding the engine dependant upon the position of the rotory intake valve. Every time a flood occurs you need to remove the glow plug and spin the engine a few seconds with the starter and a rag over the glow plug hole, Everytime.

Your 55AX (which is a great little engine by the way) gives you exact dimensions of the relationshop of the fuel tank to the carburator (jet) no matter upright, inverted or sideways. You need to stay within these specs which are actually quite wide.

My suggestion is get out the dremel tool or chainsaw and lower that tank, heck sometimes substituting a different brand of tank or perhaps a smaller tank often will help.

John

newflier1

My Feedback: (15)

Hi John:

Thanks for the suggestions. I think I am first going to try and see just how much Iam off by (meaning how much lower do Ineed the tank to be). It's a simple tank to take out (but not to lower). I think I am going to take the tank out of plane, hook everythign up, put the tank on something a bit lower than where it was in the plane and start the engine. Once I get the engine running right, I can manually raise the tank and see where my problme(s) begin. If I'm off a tny bit, maybe Ican cut something inside the plane and lower the tank. If I'm off by say 3/8 of an inch or more, then I will probably need to mount the engine horizontally to raise the carb more. Let me take a look at those dimensions about the relationship, as I don't recall seeing specific dimensions in the manual, only a picture of the engine and tank and a line being drawn through the middle of the tank. Thank you.

JohnBuckner

My Feedback: (1)

Ya I think you got the idea now. What happens a lot of times especially with newer flyers, they get some arf with included tanks that are fitted into holes into the firewall and therefore you can,t lower or adjust the tank. Many times if the fellows would just push the tank rearward out of that hole it can be lowered enough. That jammed tank bung in a hole idea is terrible anyway.

These problems show up most often where the fellows for whatever reason inverted an engine when upright or sideways was the design orientation. I realize that was not your situation but you do have that problem.

I wish you many happy flights with your pretty airplane

John

Gray Beard

My Feedback: (-1)

I think it is Sullivan that has about 50 different size and shape of tanks? Pull up there site and look. They advertise in every magazine. Some people spend the big bucks for a regulator or use a pump too. That's a lot of bother!!! You are running into one of the normal ARF problems, they design things without knowing or caring how things work. A high tank creates problems, just the nature of the beast. I have some very good cutting and sanding tools that are very narrow. Like John mentioned, the tank may be able to be pulled back a bit then the bulk head can be ground down to the required size.

newflier1

My Feedback: (15)

Thanks. Like I said to the reply to John, first I'm going to see just how much I am off, then I'll figure out what is easier to move or re-orient.

SportsFans

Hey newflier1, did you get it all sorted out?

newflier1

My Feedback: (15)

I think Imay have it figured out. I'm not sure why, but I changed the "plug" that came with the ARF's tank. It was one of those plugs that had the plastic tubes with a single barb at one end. I was playing around with the tank outside of the plane slightly lower in level to where it would be if it were in the plane. I'm using a 3 tube sysytem for my tank, fill, carb and vent. WHen Iwas filling the tank, I was noticing that as the tank was filling, fule was coming out of the carb line. I still don't understand why, the pick up is sitting on the bottom of the tank and the the fuel had yet to reach the top of the tank. So I figured something was screwed up. Ichanged to the 3 line plug all with metal tubing, put the tank in the plane, started the engine and everything ran great. To be honest with you, Ireally don't know what is going on which is sort of scary. I'll probably do one or two more ground runs/test before taking it up. It just makes no sense to me what could have been wrong with that original plug.

Weasel Keeper

My Feedback: (16)

Newflier,

I actually have this plane and felt the tank was to high for inverted engine installations. Here is what i did.

1. Plugged the original firewall hole, where the tank feeds through, with a properly sized dowel.
2. Once the glue has set, re-drill the hole about 1/2 inch lower than original.
3. Modify internal structure to support tank level with the new hole.

Seems to work fine with my TT .46 engine.

newflier1

My Feedback: (15)

Thanks Weasel. Can Iask you a question? I notice on this plane, where the tank is suppose to sit there is a "small shelf" [for the lack of better words] that sits on top (or what is the bottom of the nose retract housing). Did you remove that 'shelf'? Seems that would lower the tank by just under a half inch.

Weasel Keeper

My Feedback: (16)

NewFlier,

Just took a look and there is no such shelf in mine. Also noticed there appears to be a newer version of the PM Tucano. Maybe it is different in this regard. My Tucano has nothing but air under it. There are no provisions for retracts in my model so we must have two different scenarios. Does yours actually have retracts?

AmishWarlord

My Feedback: (5)

Have you thought about a fuel regulator? They only let fuel flow to the engine when the engine is running.


http://www.ironbaymodelcompany.com/i...es/Page438.htm

SportsFans

newflier1, yes from my experience it is normal for these engines with this inverted setup to siphone a little bit, drip, vapor lock and all that good stuff if left unchecked. I have the Pulse 60 and the 125 with this same identical setup with both tanks center line with the spary bar on the carb (though I had to lower the tank on the 60 to achieve this). I always make sure the throttle is closed and the needle valve is also closed (not tight you don't want to damage the needle valve). Fuel the model, open the needle valve to starting position, open throttle say an 1/8th, use care quickly start engine, tune for optimum performance this will also prevent to engine from loading up and dying. After starting an engine I always tune for optimum performance then back the needle back just a hair, and if I don't do this I'm looking for a dead stick. Oh yes as someone mention looping the fuel line leading to the carb over the engine mount, yes this is a must (see the purple fuel line in the attached video). Inverts are great just a little more to concider, in the 2 years of running this setup I've only had 1 dead stick, and that was due to not tuning for performance. Hope that helps...My2cents

[youtube]http://www.youtube.com/watch?v=9V8XOCwxgbI[/youtube]

newflier1

My Feedback: (15)

My Tucano did not come with retracts, but there are wheel wells in the wings and a place in the front of the fuse for the nose gear. We must have different versions of the same plane. I can probably lower the tank by just under a half inch if I take out that little 'shelf' which I can see serves no real purpose. I would have to do like you and plug the hole and drill a new hole. Imight give that a try.

newflier1

My Feedback: (15)

Yes - I was considering a Perry Pump, but I don't want to drill and tap my new engine. This is the same type of Install, you need to drill and tap the crankcase.

newflier1

My Feedback: (15)

Thanks for the pic and notes SportsFan. I think I am going to take a shot and try to lower the tank a bit. I did run the fuel line like you did 'over' the engine mount. If I take the time and lower the tank a bit, I think my problem will go away and in this model I see not real purpose that this little 'shelf' that the tank is sitting on serves.

AmishWarlord

My Feedback: (5)

No a regulator is different from a pump.

You don't need to drill your engine or change carbs.

The regulator is just a valve that only opens when the carburetor sucks in fuel. If the carb is not sucking the valve closes.

You have to install a one way valve in the pressure line coming from the muffler. This makes the fuel tank have a constant pressure of 3psi.

The regulator regulates the fuel pressure to give a constant stream to the engine when the engine's carb is pulling in air.

All you need is the regulator and a one way valve.

newflier1

My Feedback: (15)

OK - thanks for the clarification. How much does this thing weigh? Do they sell the one way valve as well?

AmishWarlord

My Feedback: (5)

Here is the one I have for an inverted Super Tigre 2300 engine in an Ultra Hots.

newflier1

My Feedback: (15)

Wow - that looks pretty small in size. Did the one way valve come with the regulator?

AmishWarlord

My Feedback: (5)

It's pretty beefy at 26 grams.

Cline makes a plastic one that has a plastic front and is lighter but cost $20 more wile looking cheap.

I prefer the Iron Bay one.

AmishWarlord

My Feedback: (5)

"The external components of the regulator are made from anodized aluminum, brass, and steel for durability and longevity. Also included are two plastic fuel line tees, a brass pressure tap, and a check valve. "

Yep comes with every thing you need.

Medium fuel tubeing will fit over that large nipple also.