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  1. #1
    Click avatar for tech links/info, donation request K447's Avatar
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    MSX 140 PTO piston holed Ficht fuel pressure regulator fails at wide open throttle :(

    This is mainly to document what can happen when a Ficht engine is running hard and loses fuel pressure.

    When the fuel pressure regulator suddenly falls off inside the Ficht fuel pump assembly in the fuel tank the actual electric fuel pump is still working, and fuel flow is still present, flowing through the fuel injectors and back into the fuel tank via the return hose.

    The problem is that without the controlled restriction of the fuel return regulator the fuel pressure inside the fuel injectors becomes very low and the fuel injectors cannot properly inject the full amount of fuel demanded by the EMM on each power stroke. They do still inject fuel, just not quite enough to keep the engine happy.

    Since the fuel pump feeds the fuel injector set from the front of the engine, typically the PTO (rear) fuel injector sees the greatest reduction in fuel pressure and circulation. So the PTO cylinder will be running the hottest from lean burn and the PTO piston is the first to get a hole melted right through the piston dome.

    In this particular case I bounced through some boat waves and then ran along some very smooth water, running flat out alongside a Kawasaki 300X that was not working nearly that hard. 6800ish RPM, everything seemed fine...

    Sudden mechanical clunk kinda sound and rapidly deceleration. Release the throttle and engine dies, which normally should not happen with a Ficht engine. Restart resulted in not normal noises and not much engine power.

    So I shut it down, turned the tow valve to the off position, get towed back to the dock

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    Tow valve
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    Back home, I used this test rig to power up the fuel pump and confirm there was no fuel pressure. Clamping the fuel return hose flat immediately caused fuel pressure at the Schrader valve tee to rise to just over 30PSI, which means the actual electric fuel pump is still working, just the pressure regulator has fallen off inside the tank.
    Last edited by K447; 07-18-2014 at 01:06 AM.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Arrow MSX 140 rear cylinder and piston removal


    Release gas cap so no air pressure in the fuel system, then remove the PTO fuel injector.
    Use rags to catch any drips from open fuel hoses and inside the injector.


    Removed plastic exhaust section and the large exhaust pipe. Don't forget the 3/4" hose hiding down low on the front of the water box
    Wriggle that large exhaust pipe rearwards, up and out of the hull. It will come out, just barely.


    With the large exhaust pipe out of the way it is time to remove the exhaust manifold.

    Note: The four long manifold to cylinder bolts will not slide all the way out until the manifold is separated from the engine.

    Here you can see the exhaust temp sensor used on the MSX 140 and the rubber bumper needed to protect the wires from the adjacent plastic exhaust pipe. An o-ring is used as a retainer strap to keep the wires out of trouble where they exit the sensor.

    Unplug the temp sensor wire harness connector.

    If you want to remove the exhaust manifold from the hull there is a small water hose fitting at the lower rear end that must be disconnected.

    I was in a hurry to see the piston dome so I had pulled the cylinder head already.

    Note that much of the wiring has been rerouted and other tweaks have been done. This MSX 140 is not exactly as it came from the factory.
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    Last edited by K447; 09-14-2016 at 06:27 PM.

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    The main problem is all the tiny particles of aluminum that spewed down from the bottom of the melting piston crater.

    Feeler gauges tomorrow will confirm the lateral play at the crank big end.

    I shall decide what I want to do about all this tomorrow...

  4. #4
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    Is it fixed yet?


  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by BryanP View Post
    Is it fixed yet?
    Draining the fuel tank as we speak. Next I need to get the fuel pump out. Remind me how to do this with the least amount of bad words uttered.

    Tomorrow I buy the replacement cylinder base gasket and hopefully I can get the engine bolted back together.

  6. #6
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    I removed the steering assembly. Then you can pull the pump straight up and out without moving the tank. Its really not that bad to do. I think some of the other workarounds people have posted would cause more swearing than just removing the steering. The worst part of the job was getting the pump back in the tank with the rubber donut.

  7. #7
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    Trying to reattach the rubber strap on the fuel tank retaining bands is harder to do than removing the steering. I replaced one of those on my 140 and the one closer to the engine was almost impossible to get on.

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  9. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by BryanP View Post
    Trying to reattach the rubber strap on the fuel tank retaining bands is harder to do than removing the steering. I replaced one of those on my 140 and the one closer to the engine was almost impossible to get on.
    John sells these, Randy sold me one a few years ago.

    Or make your own
    http://www.greenhulk.net/forums/show...=1#post2285908

  10. #9

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    This is a problem on the TXi's also I assume? How can one prevent this problem? What are my options? It seems to me if the regulator fails, you would notice/feel something immediately.

  11. #10
    Moderator beerdart's Avatar
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    I just did my 140 as preventive maintenance the plastic boss is the correct size to tap 1/8 NPT then install 1/8 NPT barb.

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