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Thread: Forced landing 11/06/11

  1. #11
    Senior Member
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    Default Re: Forced landing 11/06/11

    Don't forget your vent lines. For fuel to flow out, air has to flow in somewhere.

    Roger

  2. #12

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    Default Re: Forced landing 11/06/11

    I put the video up on youtube you can see whats happening


    http://www.youtube.com/watch?v=1oLX8DQysCE

    in this second video you see it will run on low power settings, but around 9 min 15 sec. at high power it dropps and then really drops

    http://www.youtube.com/watch?v=ku7sEYc0Ces

  3. #13
    Senior Member Wheels's Avatar
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    Default Re: Forced landing 11/06/11

    I had an Identical power failure a few months ago. I replaced the entire fuel system. The carburators may have been the problem but finding a new fuel pump is the problem now. The one you mentioned wasn't in stock when I called the manufacturer. He no longer supplies a pressure regulator with it. He said to get one from a performance shop but I am having my old pump tested and if it tests good, I"ll use it until the manufacturer comes up with a replacement item.
    Jack

  4. #14
    Senior Member Dave S's Avatar
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    Default Re: Forced landing 11/06/11

    A couple additional tips on potential fuel restriction.

    1) The "T" on the 1/4' line which splits the flow between two carburetors on the rotax can be a spot foreign material can hang up in. Any place a line goes onto a metal fitting may provide a place for material to hang up on.
    2) When cutting in new fuel line or replacing fuel system parts - never assume the new line is free of bad stuff - good idea to cut the replacement line, then hit it with the air compressor and run sufficient fuel through it next to be sure it is clear before installing - look into the ends as far as is possible. Same with fuel pumps and filters - run fuel through them for a flush before hooking them up.
    3) When you are all done - get a new gravity flow rate at the carbs - the data can be used for future comparisons as a quick test to see if the system is still flowing correctly.
    4) When you are all done - get an operating pressure reading between the pump and carb with a temporary gauge if you don't have an installed gauge - again - this will provide data for future comparisons as a quick test to see if the system is still operating correctly.
    5) Fuel systems can mess up in several ways - slow deterioration caused by swelling lines, clogging filter or a wearing pump can often be picked up during annual checks using 3) and 4) above - long before it becomes an operational issue.

    It is amazing how close to zero fuel pressure can be with a high flow rate under full power on a carbureted system without causing a hic-up - but then it is right on the edge failure.

    Sincerely,

    Dave S

  5. #15
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    Default Re: Forced landing 11/06/11

    Jack ,
    Check this out from Rotax-owner.com forums.The new pump from Rotax might solve your problem.Roger is a great guy and knows these engines !

    "Hi all,
    Just a quick note about the new Rotax fuel pump. The first production pumps did have a little issue at times with high fuel pressure and I understand it was from an issue at assembly and not the actual design. The newer production models don't have that issue. If you do happen to get one of the new fuel pumps that are too high in fuel pressure then send it back and they will be happy to replace it. You should always check the fuel pressure when installing a new pump and or an electric pump. Many have fuel pressure gauges in the cockpit and that works. If you don't then hook up a mechanical gauge and check the pressure at cruise rpm (i.e. 5000-5300 rpm) on the ground."

    Roger Lee
    LSRM-A & Rotax IRMT
    Tucson, AZ Ryan Airfield (KRYN)
    520-574-1080 Home (TRY HOME FIRST)
    520-349-7056 Cell

  6. #16

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    Default Re: Forced landing 11/06/11

    Ok I just got the new pump and it's different. pt# 893 110, it has a fuel overflow line and different size barbs on the inlet/outlet. Is their anything I need to do for this installation? Can I just adapt the hose to fit new barb?
    To check the pressure (every one seams to agree I need to have a pressure reading) can I install a pressure gauge and read it from there?

  7. #17

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    Default Re: Forced landing 11/06/11

    New fuel pump no joy, same trouble, good news I have 2 fuel pumps!
    So I will start going through the whole thing, thanks for everyone's input Iv'e got plenty to look at.
    Guess I will have to rent to get some flight time.

  8. #18

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    Default Re: Forced landing 11/06/11

    pump was my best guess, I'm coming up with a plan. I don't want to replace my whole fuel system I want to find whats broke and fix that. It would be a waste to just rip everything out if it's not broken. I think first I'll go from gascolator to carbs looking for a clog. If nothing then my headder tank to on/off valve if not that change the lines from tanks to header. At that point I'll have changed the whole fuel system.
    It started all at once, only happens after a minute of full power, and was flying great I fly almost every day 7 to 12 hours a week (building time to get a job). I took a week off and came beck to an emergency landing. Now Iv'e got ground sickness and need to fly.

  9. #19

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    Default Re: Forced landing 11/06/11

    So the new pump didn't fix it, I started following the line back checked the Flow rate, it was really low with gravity feed.

    gascolator was fine, then I got to the main fuel shut off, and I recalled that two weeks ago it got really easy to switch on and off. Prior it took pliers and I was planing on looking into it.

    When I took it out, with my wing tanks inline valves off, the header tank drained just fine. The on/off main valve was missing a retention cir-clip, you could just pull the the thing right out of the valve body. I believe it was pulled out just enough to slightly retard fuel flow. After this the gravity feed is 1/6 a gallon in 15 min.
    I will put it all back together on Monday and run it up to see what happens , crossing my fingers.

  10. #20
    Senior Member jtpitkin06's Avatar
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    Default Re: Forced landing 11/06/11

    The flow rate of 1/6 gal in 15 minutes is inadequate. At take-off power the engine may consume over 10 gph or about one gallon in 6 minutes. You need at least that amount of flow in gravity feed. Preferably more.

    Remember it is gravity feed that supplies the fuel pump. The pump supplies the carburetors.

    If the pump doesn't get the supply it will cavitate or quickly drain the header and start sucking air.

    Keep looking. You have something blocking your fuel.

    JP

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