Pressure fuel systems

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    Scott Lapraik

    Good afternoon everyone! I have just purchased my first setup for a pressurized fuel system from Hank Nystroum(sp) and I would like to get any assistance in the engine starting process. I.E. pinching the tube before the engine starts. Needle valve setting as compared to suction type system. Any assistance will be appreciated.


    Scott J. Lapraik
    Portland, TN

    Dean McGinnes


    You did not say whether you were hand starting or had a starter motor. As to hand starting, I can’t help you much as I don’t recommend it. An electric starter motor will transform this sometimes aggravating operation into a straight forward event.

    For a first start, I recommend inverting the engine. The main reason for this is to prevent flooding and hydro locking the motor. For a .19 sized engine, open the needle such that about one drop per second is dropping out the venturi, engage the starter and hit the button. The engine should fire off. Then open or close the needle as needed.

    You will find that the needle will not need to be opened as far out as with suction feed.

    I am not where my computer is located and will not be there until Sunday, but I have a website bookmarked that deals with hand starting. I think it is Larry Driskill’s site called, or something similar. If you don’t get a good answer for hand starting. That said, I still do not recommend hand starting.

    Again, life is greatly simplified with an electric starter setup. 🙂

    Norm Furutani

    Dean’s advice on the drip test is right on.

    Here’s my favorite site for making and using the pressure/bladder system.

    The use of the Perfect line clip for a shutoff is very handy

    – Norm


    >life is greatly simplified with an electric starter setup.

    That’s very true .. but until I ‘inherited’ an electric starter box two or three years ago I’d been handstarting pacifier-fed engines, up to .40, by hand for over 30 years without any problems (well… maybe one small row of stitches …) Fill pacifier, close timer, prime, press fuel line flat with one fingertip, open timer, flip, release finger .. etc. Just a matter of habit .. but a starter does make the handling of the model easier.


    OK, here is my two cents worth….

    If you can, use a starter. If not you have to be somewhat quick on the draw, as you have to release the line after the engine sputters to life.

    I do not believe you have to have an inverted engine, as we have not had one for many years of successful running. But, you will need to learn the flood cleanout technique. This is simple. Just flip the airplane upside down while rocking the prop. Continue rocking the prop as you rotate the airplane over, with any excess fuel running out of the exhaust.

    Here is how we (John and I) start a new deal. Fuel the airplane and pinch off the main fuel line. We normally have some method of pinching the line attached to the airplane but a forceps or equiv will work. Crank the needle down gently until it is fully closed. Attach your glow clip and release the pinched line. Jam the engine into the starter and get it rotating. Open the needle until the engine fires. Then adjust as normal.

    If you miss the engine start, you will need to pinch the line. Jam it back into the starter and use the fuel in it to get it started again. When it fires, slowly release the line until the engine can use the fuel you are feeding it. Use the line pinch to vary the engine rpm until it gets up to speed. If rich, then lean it via the needle as you normally would.

    One thing to remember is that the needle valve may need less movement to adjust. Take it slow and easy and you will soon find the happy spot.

    Play around and you will find that this is the only way to go!![/img]


    John, that’s pretty salient advice.
    Scott, it is actually pretty easy to work a bladder system. It is absolutely helpful to practice with the procedure until you are comfortable and consistant with it. If ypu go to the field to fly and fight with starting procedures, you GUARANTEED to get all excited about getting the engine running and launching into a nice thermal only to realize that you forgot to light/set a DT. Happens all too often.

    John, the photo shows a broken prop. Get a new one before flying again!
    Do you have a detail pic of the fule switch device? I cannot figure out how it works with only the one photo.

    Norm Furutani

    @John Lorbiecki wrote:

    I do not believe you have to have an inverted engine, as we have not had one for many years of successful running. But, you will need to learn the flood cleanout technique. This is simple. Just flip the airplane upside down while rocking the prop. Continue rocking the prop as you rotate the airplane over, with any excess fuel running out of the exhaust. —-snip—

    Hi John,

    Didn’t mean to infer running inverted engines, but to turn the motor inverted to clear the needle and do the “drip” test before starting.

    I too, am very curious about the shut-off in the pic. Looks simple and clean. Could we get more pics and a descrition of how it works? Also the timer end, too?




    Salient???? What the heck kinda word is that outta your mouth??? Plus, I paid alotta money for that broken prop…

    OK, my fuel system is really very simple. I use the typical Tee, with the surgical tubing attached to the long leg of the tee. One end of the tee goes to the needle valve assembly and the other end goes directly to the flood off fitting. Now, here is the trick part. I make a secondary firewall out of .032″ thick aluminum. This then has the little hook that you can hopefully see in the picture that holds the fuel line shut off lever.

    On the other side are two small hole (.04″ dia) that a piece of flexible fish line goes thru. The line is looped thru these holes and the long end is attached to the timer. The fuel line goes thru the loop of the line and when the line is pulled, it pinches the fuel line. Release the line and the flood off line is opened up. Very simple and light and failsafe….

    The trick when you make the wire deal is so that when it is closed it pinches the line off. Note that the fuel line is squeezed against the lug to pinch the line off. I think I used .024″ or so diameter wire. The thing is great to use to regulate the engine until it builds up heat and gets into tune.

    Hopefully you can see in the ics the hook that the fuel shutoff attaches to. It workes very well and is simple to make…


    And here is a pic of the fuel system I use…..Just surgical and home made brass Tee….One end to the needle valve and the other end to the flood off…

    Oh, and the plug in the bladder is just a pellet (the kind you shoot). I use copper wire to clamp everything together or, what works really well is the wire that is in the typical ties that are used for bread bags and such- It is very flexible steel wire….


    I have not done a lot with pressure systems, but I use a pre-fabricated T and instead of putting a plug in the end of the tubing, I just put an overhand knot in it.

    If you would like a picture of the T, look at the 3rd picture down, and there is an engine mount with the T mounted inside:

    Dean McGinnes


    Perchance do you have a picture of the fuel line pinch wire and how it attaches to the engine? I can see the loop where the fuel line goes through, but can’t see how it is mounted or hinged. 😥

    Norm Furutani

    Hi John,
    Thanks for the pics and explanation. I thought I was looking at a simple pinch-off system, not a flood-off. The shut off we’re seeing in the pic is for fueling and starting, not the timer shut-off, correct?

    Is the flood-off nozzle on the needle side? That’s why we can’t see it?

    What I’m looking for is a simple, lightweight pinch off system that works off a traditional wire bail timer release.

    – Norm


    Hey John
    Does the pinch-arm just hook under a little tab at the backplate are. I can’t quite make out where it latches. It looks easier to make than what I’ve been using. Kina Luddite’esque actually.


    Yes, it is just a fuel shut off for starting.

    The pivot is just a hole drilled in the engine lug and the end of the wire is bent thru it. And, yup Dan, the hook is on the aluminum plate. It works very slick and is very simple to due. It just takes a little bit of bending to get it right. Then it works forever!

    The flood off fitting is on the left side of the engine. The needle valve adjustment is also on the left. The main fuel line is on the right.

    Why not flood the engine? It has everything good going for it.

    1.) The engine stops right now, no run down

    2.) You don’t have the weight of the excess fuel in the bladder- less weight, no change in CG if there is more or less fuel in the bladder.

    3.)It is MUCH simpler to make the flood off system, as you just need a hunk of line. Plus, it is lighter because you don’t need the pinch off mechanism.

    Bad stuff

    1.) You waste more fuel (I use 8 CC of fuel on the F1J) as it is blown overboard

    2.) The engine does get a load of fuel, but most times it is just enough to start the engine on the next run.

    Some people have the misconception that floodoff is harder on rods. Been flooding engines for 30 years and never broke a rod or seen excessive wear eqauting to the flood off..

    So, everyone should use flood off!!! And, even Luddites can use it!!

    3.) Ahhhh, can’t think of anything else


    More pics…

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