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SkyMaster MB339 Build Thread

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SkyMaster MB339 Build Thread

Old 10-09-2019, 09:40 AM
  #426  
TeamMuir1
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Good eye... the only part that touches would be the top of the UAT.... ive got a solution....as before in my posts i showed that my cockpits are junk lol and that im going to be doing a rebuild on them.... i will post pics when i get on them... seeing as this weekend is the end of our jet meets... i will have more time to work on them....
Old 10-13-2019, 07:38 PM
  #427  
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Was not able to get any flights on the 339 this weekend.. I just dont understand just yet whats going on
with the P-180.... some said it was the battery .... was not big enough... some say that the C rating was
to small... I went from a 20c to a 60c and still the same problem.
I guess I will do some diagnostics .... I was told that the turbine needs more kero for start up... and I
have the programming steps to do just that ... but that just does not explain how I got 3 flights with
out a hikup.... and now it just wont start... looking down the pipe it flames up... but what seems to happen
it shuts off when it switches to the second solenoid to run ..... valve turned on.... no air bubbles.
It just seems as though something stopped working.
NOW.. I am no turbine tech... but it sure seems as though I will have to start trying to be one LOL.
only problem that I see.. it will cost me some $'s for some new replacement parts... if I am going to
hang on to these motors.. I guess I will have to stock up this winter on PARTS.... ECU's .... Soleniods....
Circuit board with the LED lights that blink... lol... I dont even have a book to tell me what these parts
are called.. lol I swear... as nice of a weekend it was I sure missed out on some good flying with the
339..
Old 10-14-2019, 04:21 AM
  #428  
basimpsn
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Seem like your fuel solenoid might be blocked or not working...Quick and easy test is to use the test function from your GSU to switch the fuel Solenoid on while blowing pressure into the fuel line.
Old 10-14-2019, 05:58 AM
  #429  
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That seems like a GREAT TEST.... I will do just that and report back.... I guess I could test both solenoids.
while I am at it....
Old 10-14-2019, 06:38 AM
  #430  
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Given the info I also suspect a simple solution. The Software on the ECU has several test functions, like the one written above.
Also the pump can be tested, but again, do disconnect both fuel lines from the engine in order to avoid flooding and having to deal with a fiery startup next time.. Put a rag at the end of the open fuel line or a long fuel tube that expels the pumped fuel outside of the plane.
Naaahh, You don't need so much spare parts, ECUs are normally costly and if they malfunction, a new one can be ordered quite fast.
Yes solenoid valves might malfunction one in a while, but they also can get obstructed when the fuel is not fliltered inside the plane.
I use the hopper tank as filter, and have replaced long time ago all fuel filters inside the tank

My Wren engine has been serviced and the culprit might have been just the data cable, the *black telephone type of cable" , which proved to be unreliable.
So we will see at the next flights if they were right....
Old 10-14-2019, 06:57 AM
  #431  
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Originally Posted by TeamMuir1
That seems like a GREAT TEST.... I will do just that and report back.... I guess I could test both solenoids.
while I am at it....
I have a kingtech engine with the same problem...Start ignition shows ok but switching to fuel..the flame goes out. Turns out one of the fuel solenoid two wires broke off..Repair it..two years later still going strong. I did a video sometime ago on how to check problem.

P.S I love my Mb-339

Last edited by basimpsn; 10-14-2019 at 07:11 AM.
Old 10-14-2019, 09:19 AM
  #432  
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Ok this is what I know I found a great video about the Jet Cat


I have not gotton threw the entire video yet... I made it to the point
were I can jump the throttle to the air speed sensor and then plug
the battery in so that I dont have to keep powering up the PLANE
I used a jumper extension then a servo extension leaving the battery
plugged into the ECU now I can power up the ECU with out using
the radio in the plane.
I found the menu were to prime the fuel system.
I disconnected the Y festo from the pump and activated the priming
system in the menu and the fuel comes out of the pump... NO PROBLEM
I installed the Festo again and tried it and NO Fuel passes threw
the solenoid going to the motor. Now correct me if I am wrong. but in
order to prime the system the fuel has to pass threw the solenoid to the
motor.????
I will look on and see if I can find a solenoid test. I am thinking
I found it but its named a little different.
Old 10-14-2019, 09:30 AM
  #433  
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in the video the guy disconnects the fuel line going to the motor.... I did just that
and performed the test. NO FUEL passed threw the Solenoid. I think thats
the problem. So if I had another solenoid I could change it out and put that theory
to the test. ONLY question I have are all the Solenoid's the same for JET CAT ?
I have 2 other motors I could change out the Solenoid's to test.
Old 10-14-2019, 09:47 AM
  #434  
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I have another set of Solenoids and I tried what you said.. blowing threw the fuel line
while holding the button for the fuel purge and NO LUCK it does not open up the
solenoid.
I am only questioning the process... since its the same out come with another
set of Solenoids.
Old 10-14-2019, 10:00 AM
  #435  
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Originally Posted by TeamMuir1
in the video the guy disconnects the fuel line going to the motor.... I did just that
and performed the test. NO FUEL passed threw the Solenoid. I think thats
the problem. So if I had another solenoid I could change it out and put that theory
to the test. ONLY question I have are all the Solenoid's the same for JET CAT ?
I have 2 other motors I could change out the Solenoid's to test.
So your fuel solenoid is not working....I'm sure if you bypass that solenoid just for testing..the engine would start right up.
The main uses for that solenoid is to prevent fuel from leaking into the engine while you're fueling the plane...If you decide to try this test..close the manual fuel valve when fueling then open to start.
Old 10-14-2019, 10:10 AM
  #436  
basimpsn
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Originally Posted by TeamMuir1
I have another set of Solenoids and I tried what you said.. blowing threw the fuel line
while holding the button for the fuel purge and NO LUCK it does not open up the
solenoid.
I am only questioning the process... since its the same out come with another
set of Solenoids.
Well if your solenoid is good then it's the driver to the solenoid..ECU problem. Try bypassing it and see if it starts...;-)
Old 10-14-2019, 06:05 PM
  #437  
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Thas a Great idea..... bypassing the solenoid run straight to engine..... if thas ok to do i will do that next.... tomorrow evening.....i take it that the pump wont just dump fuel continuosly to the engine ? If i knew i could have done that earlier it shuts down when it switches to the fuel....
Old 10-15-2019, 03:57 AM
  #438  
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Originally Posted by TeamMuir1
Thas a Great idea..... bypassing the solenoid run straight to engine..... if thas ok to do i will do that next.... tomorrow evening.....i take it that the pump wont just dump fuel continuosly to the engine ? If i knew i could have done that earlier it shuts down when it switches to the fuel....
"i take it that the pump wont just dump fuel continuosly to the engine ?"

The fuel solenoid is just a extra safety valve to prevent overflow of fuel into the engine "ONLY DURING FUELING". I remember when engine never have solenoid only manual gas switching valves lol. But if your going to do this keep in mind to close the manual valve while fueling and open during starting.

P.S do this at your own risks lol

Old 10-15-2019, 05:48 PM
  #439  
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Thanks for the tip..... it started right up..... i was shocked...lol
i was so happy i actually ran the motor up....a couple times...in fact I was having so much fun....I ran the dam thing out of fuel..... lol....
so i shut it down.... filled the tank up half way.....and tried starting it again... i wanted to make a video... well that didnt work out as planned... lol the dang starter motor now wont
allow it to start.... geeze.... buddy of mine says the oring needs flipped... ( what ever that means ).... i say just replace it... so I guess I will order some main thing it started and I guess I need new ECU.....
Old 10-16-2019, 03:30 AM
  #440  
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Awww man...multiple fail starts will burnout your starting motor and O ring. You could purchase the O ring set from amazon...or removing the Oring and flip it around. As for the ecu you could get away with using it the way it is.
Old 10-18-2019, 05:29 PM
  #441  
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Yeah... I guess the oring was just old to begin with my buddy... tells me if a motor has been sitting
like he thought mine has been.. the O-ring can get hard and brittle... so I have ordered 5 from
dreamworks... buddy wants 2 and I will have 2 for spares.. down the road.
The ECU... more than likely will be sent in this winter.. let them fix it... while its snowing.. lol
your right I can use it the way it is.... and I will more than likely this weekend.. get in a few
flights..
Old 10-19-2019, 11:08 AM
  #442  
ravill
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I haven’t run fuel solenoids for years.
Old 10-21-2019, 04:38 PM
  #443  
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Originally Posted by ravill
I haven’t run fuel solenoids for years.
I guess i would like an explaination about not using solenoids..... dont you have to on kero start ? Other wise wouldnt the fuel pump just dump fuel in the motor ?
the ECU turns off the solenoide so it doesnt flood Right ??
Old 10-21-2019, 05:05 PM
  #444  
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Originally Posted by TeamMuir1
I guess i would like an explaination about not using solenoids..... dont you have to on kero start ? Other wise wouldnt the fuel pump just dump fuel in the motor ?
the ECU turns off the solenoide so it doesnt flood Right ??
If your kero start engine has solenoids on the outside of the engine, then yes, you need them.

I have one kero start engine that has solenoids on the outside (B300F) and all my other kero starts have solenoids not accessible to me under the front of the turbine.

My 3 biggest work horses are propane start and they don't get solenoids or filters.
Old 07-07-2020, 06:17 AM
  #445  
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Old 07-07-2020, 08:30 AM
  #446  
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Nice flight. Love that Howl!
Jim
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