AAbdu

My Feedback: (18)

Let me start by saying I have run everything from Wankel 30s to YS 170 DZs, however I am very new to turbines.

I have a Wren SS mounted in a Boomerang Sprint that used to start and run perfectly! The plane has two trim flights on it but otherwise very little time. I have run the motor in my front yard 5 or 6 times and it has always started flawlessly, and that is how it was when I put it up last winter.

I got the pane out this year and fueled it up, including Powermax. It started up and ran well. I shut it down and went to do my chores. The next day I tried to start it I had very little luck.I eventually got it running but it flamed out (was probably low on fuel), I fueled it up and after a bit of doing got it running again then shut it down. I have not been able to start it up since. For some reason, it just WILL NOT LITE!

I have tried adding more Powermax, opening the valve after the solenoid to get more gas, and numerous restart attempts. When I try to start it this is exactly what happens.

1. Turn on the power to everything (all batteries freshly charged)
2. Put the trim in the start position and look at the display (it says ready)
3. Advance then lower the throttle, display shows each step (glow test, ignition, RPMs, etc)
4. Electric motor spools up the engine.... then nothing
5. Eventually the display says "Timed Out" while the motor coasts to a stop.
6. Shut everything down then repeat

I did notice condensation on the top of starting fluid tank, I don't know if that means anything just figured I would add every detail so you experienced Wren users can help solve this issue. I feel like it is something simple but I just don't know what to try next.

I would appreciate any and all help you could provide.

Thank you
Anthony

frema

Hi Anthony.

dont be afraid to open something.
first , get the glow plug out , and ,very carefully pull the glowwire of the plug ,a little bit more out.
then ,check if the gaspipe is open.
delete the gas valve ,dont use it ,it can be that the valve is not open fully ,or not open at all.

so delete the gasvalve ,and ,if you are shore the gas pipe is open , when you blow with your mouth , you have to hear it in the engine .
if you can not blow throug it ,you have to open the engine , then something is blocked.
but first try the things i told you above .
i had the problem too with a wren , and what i did when the gaspipe was block ,was high pressure air , blow in the gaspipe , andf it was open .

hope this helps.

Regards,

Martin.

AAbdu

My Feedback: (18)

Martin,
Thanks for the heads up. I actually spoke with Ron of Wren today (thank you Ron and I'm sorry to bother you on a holiday weekend!!!!). Took a very close look at the glow plug and it is operating properly. Power is set to 36. Tried it again with no changes. Took the propane tank out and gave it a careful once over, everything looks fine there. Refilled the tank, even though it did not seem to take very much power max. I saw the starting fuel go in for about two seconds then nothing so I figured (perhaps incorrectly) that it was full or had a least enough for one start. Tried again, same result. My guess would be that either there is NO gas in the propane tank or the gas that is in there is not getting past the propane solenoid, I don't quite know how to fix that but I will be up all night trying.

Thanks again for the help.
Anthony

causeitflies

Try doing a propane valve/solenoid check and listen closely for gas in the turbine. If no gas do as Martin suggested and eliminate the gas solenoid.
On the other hand if you do detect gas entering the turbine, try turning it down. Too much gas is as bad as not enough.

AAbdu

My Feedback: (18)

Mark,
I did a search and just found out that too much gas can be just as bad. I just assumed it wasn't getting enough. In the morning I will close the valve and start fresh from 1 turn out and work my way out and see if that helps.

Silly question, how do I bypass the solenoid and still meter starting fuel to the motor?

causeitflies

Sorry, forgot you are using on board gas. Many of us use off board propane without the on board tank and control it that way.

frema

its very simple to do that.
just disconnct the valve from the ecu ,and take the line that go's to the engine ,from the valve ,and connect a small gas bottle ,the bottle you fill with , and then try it .

what kind of bottle do you use to fill with?

Martin.

AAbdu

My Feedback: (18)

I fill my onboard tank from the big Powermax bottle

frema

well use that bottle to start the engine directly.
be carefull how much gas you give the engine.
if you see to much flames when the gas ignites , close the valve .

AAbdu

My Feedback: (18)

PROBLEM SOLVED.... Kinda. First of all I would like to thank everyone that offered their assistance, it is much appreciated. A special thank you goes out to Jim Hiller who donated a ton of his precious flying time to help me get the Wren sorted out.

As it turns out I had a number of problems.

1. Even though I did not get a glow error, the glow plug element was not out far enough or working properly in general. With it out I could light it with an igniter it would glow orange, however it was not getting hot enough at the exposed tip to ignite the gas, which leads to problem 2

2. Too much propane. My propane needle valve was too open so the engine was getting too much fuel to ignite. Couple that with a cool glow plug and you got problems.

3. Gas solenoid was not functioning properly. Upon inspection some of the guys noticed that gas just kept flowing even when we weren't trying to start the motor. One of the guys (whose name I unfortunately can't remember (I think it was Bill)) painstakenly took it apart and found a huge hunk of crud in it.

After all that we just kept trying to start it until we found the needle valve sweet spot (kind of). We did get it running and with a couple more adjustments were able to fly it, but it is not starting consistently enough for me. I would like it to work like a Wren should and start first or second attempt every time. I will keep making fine adjustments to it until it does.

I have read the manual several times over, but there is no substitute for the assistance of an experienced jet modeler.

Thanks again guys
Anthony

causeitflies

Glad Jim got you sorted out.
I was going to add to make sure the plug was glowing BRIGHTLY when testing. Should have suggested that.
I always run a filter in the gas line before the valve and the solenoid. As you found out, crap does find it's way in the system. I ended up just removing the solenoid after it gave me fits at a fly-in.

Just ran my SS today after swapping into another plane and it is a sweet engine.