H E L P Still without a clue PART II

[Paul Taylor]

OK, no more fuel in the case. That I am sure was because of haning the plane nose down with fuel in the tank.

So with the engine out of the plane and the clunk tank I mounted it on the test stand. It would run out a prime and then quit.

In order to trouble shoot my clunk tank, I took my LA .40 and put it in the stand with the clunk tank. I double check and trippled check the fuel lines to make sure the pick up was going to the NVA. The two other vents go to the top of the tank. One for muffler pressure and the other is the fill line. I put a screw in the fill line and hooked up the muffler. I put my finger over the vent and pulled the prop over. The fuel did not come up the NVA line. Must be an air leak. I put on a new fuel line for the pickup. Still it would not pull up the fuel. If I drop the fuel line lower then the tank the fuel would run out. So I have a problem with the tank. I replaced the tank with a 2oz tank that I use on the test stand all the time. Guess what the fuel still did come down when I put my finger over the vent and pulled the prop over.
Boy do I fill like a bone head.

Pictures of the LA .40 with 2oz tank on stand.
And a picture of the tank out of the plane that was used.

Paul 

[Wynn Robins]

are you putting your finger over the vent??   should be ON THE VENTURI.

Also - putting a screw in the line will not seal it from air - air goes in between the threads of the screw- use a fuel line plug - or a smooth shaft bolt ot bit of wire.

what you have looks OK - just put the muffler pressure hose back on - plug the overflow (vent) put your finger OVER THE VENTURI - to get a seal, pull the prop over a couple of times.....
let me know how you go

[Bill Heher]

Root beard- Wynn is correct, you need to put you finger over the venturi- this is the same as closing the choke on a something like a gas powered weed eater or edger.

Another way is to have the muffler pressure line hooked up, open the needle a good 3-4 turns, put your finger over the muffler exit and flip the motor over. All the exhaust pressure will be forced into the tank- more so than if the muffler exit is open- resulting in greater pressure in the tank.

You should easily see fuel get pushed up the supply line to the engine, and fill the venturi.

[Joe Messinger]

Paul,

You've gotten good advice from the fellas and I doubt that my explanation will help much but I thought I would at least try to offer something  as I have had about the same type of trouble in the past.

Here's my tank set up for Sullivan plastic tanks:

*Copper line going from the -top -(inside) of the tank bent and exiting straight out through the cap and extending 5/8" out past the cap.  Fuel line attached to this, turned down and routed to the muffler for pressure. I use a strap to secure the tubing below the bend. Don't over tighten the strap! This line also serves as the overflow.  Disconnect when fueling.

*Copper line from  the -bottom- of the tank bent and straight out 5/8".  Fuel line goes up and above the fuselage (1").  Same strap set up.

*Copper line -straight- into tank extending 1/2'" (from the stopper) into the tank and 5/8" beyond the cap outside.  Flexable fuel line supplied with the tank with sintered bronze clunk and attached to the straight, copper tubing inside.  Fuel tubing outside on this one to the NVA.  Try to keep the fuel supply line oriented to the middle of the tank. 

Make sure the clunk moves freely in the tank.  Clunk should be about 1'8" from the back of the tank.  I cut small (1/4" long) pieces of the tubing supplied with the plastic tanks to secure the flex lines to the copper inside and out.  Cut off a piece of the smaller tubing, slip it over the ends of a pair of forceps or small needle nose pliers, open the tool to stretch the piece and slide it over the fuel tubing.  Slip the fuel tubing over the copper tubing and clunk and slide the retainer piece over the fuel tubing and copper.  Do that on the copper exit points and the NVA end also.

I cut a 1" long piece of copper tubing and slide it 1/2" into the fuel fill line.  Leaves 1/2" extending out of this line for filling the tank.  Cap off the copper after filling.

I've had good success with this set up on both on profile tanks and tanks mounted inside the fuselage.  Works fine with or without muffler pressure.

As a side note,  I had one Super Tigre NVA that allowed fuel to pour into the venturi even when the needle was screwed all the way in to the seat.  Close examination showed that the needle had very light cuts all the way down one side of the tapered end which allowed fuel to run past it.  Must have bumped the thread machine as it was being made?

I'm sure the above is over explained and nothing revolutionary but I know how frustrating problems like yours can be.  Sometimes it's best to go back to square one and redo everything.

Hope this might be of some help to you.  Good luck with everything.  I'm sure you'll get it figured out soon.

Regards,

Joe

[catdaddy]

Paul
Are you still having problems? The end of your post wasn't very clear. If you're still having problems with the engine running on prime only I'd make sure your needle valve body is not clogged with castor. Did you say this engine has been in storage over the winter? If so you may have some trash you need to flush out.

[Paul Taylor]

OK let me try this again.
All I use is clunk tanks. I have setup a few of them. Ryan's Tutor runs great on one with muffler pressure.

I have two engines, FP and LA 40. I have tried two differnt tanks. When I choke the engine with my finger over the venturi the engines will not draw fuel. The will run out a prime fine. Just will not draw fuel. If I let the pick fuel line hang down lose, fuel will run out onto the floor. Both engines were running fine last fall.

I am puzzled why they will not draw fuel.

Maybe I backup and start all over.

Paul 

[Paul Taylor]

OK, I got the LA to run on my test stand. Had to open the needle up.

Now to try the FP, then the other tank.

[catdaddy]

OK, I got the LA to run on my test stand. Had to open the needle up.

Now to try the FP, then the other tank.

Never mind saw the other thread

[L0U CRANE]

Paul,


To your reply#6 - Have you checked the filter and spraybar for blockage? And the photo of the larger tank - the problem tank, I presume - shows the pickup tube going WAY back towards the rear wall. It can happen the the clunk jams agains the back end and doesn't allow fuel to flow in the tubing. But, if the fuel flowed through when the fuel tube was disconnected from the engine, and drooping below the tank....?

It doesn't necessarily suggest a tank problem if the fuel flows from gravity when the spraybar end of the feed line is drooped below the rest of the tank. Doesn't rule it out, either. That your engine worked when you opened the needle suggests either that the needle was closed too far to begin with, or that the filter or spraybar was partially clogged.

Sometimes it's the littlest things that we can't see...

Luck, and I hope that is all it was...