DLE35ra having fits
 

Mounted on TF Stinson SR9 in cowl. Been flying early mornings lately and flew again yesterday morning, no problem. Tried last evening and about 3 to 4 minutes into flight engine began to sputter and would not run wide open. Managed to just keep it going long enough to land safely.
Morning temps in the 15 to 18C range while last evening was 27 - 28C.
Adjusting needle valves did not seem to make any difference to it. Would start, with choke, idle for a few moments, but if tried opening throttle would quit. I noticed what looked like gaps (fuel then air?) in the gas line. Do you suppose this could be a cooling problem? That the fuel is vaporizing in the high heat conditions, indicating the cowl cooling is just borderline. Ok when air temps are cool, but not enough when hot?
Raining and windy now so can't take it out to try running it this morning.
Any thoughts and suggestions on this would be appreciated.
Thanks everyone.

Re: DLE35ra having fits
 

From my experience; This sounds like a fuel starvation problem. :itsok_170:

I would suggest that you take the carberator off and check the filters. There is a small wire basket filter on the carb that can plug up with dust and 'Stuff'.

Often; it allows enough fuel through to run, but under flight conditions the amount of fuel that gets through amounts to a 'LEAN' running engine and then the engine overheats and quits. (does this sound like your problem?) :TD:

The Solution is to buy a carb rebuild kit (~$20) and replace the filter plus any questionable parts.

I would also recommend that you flush your fuel tank and check any other in line filters. :TU:

Happy Landings!

Re: DLE35ra having fits
 

Very unlikely the fuel is not vaporizing. Guessing the engine is overheating or you have a hole in a fuel line, tank, filter etc.

Re: DLE35ra having fits
 

Clunk still attached to the line

Re: DLE35ra having fits
 

You could try pressurizing the tank with crank or muffler pressure to boost the fuel to the carb..It would stop all forms of starvation and negative pressure in the lines. I thought it seemed to be a little rich last I saw it flying (video of maiden flight shows small smoke trail).Could it be ignition related?
I have never owned a gas engine for a plane but I did stay at a hotel once!...Lol

Re: DLE35ra having fits
 

BBBair: Not sure about fuel starvation exactly. Runs just fine if the air temps are cool. Over 1 1/2 hrs running this way. (Approx 2hrs total run time on engine)
New fuel tank was flush before install--twice! Fuel lines all had gas pushed thru. Direct line to carb. Fuel fill valve also had gas thru it prior to install.
Mike: Pressured up the tank and fuel lines. Left it for over an hour. Tank was still under pressure and visual inspection showed no signs of any gas leakage so I think I will check off thaat it is not this.
Crash a lot (and you did LOL): Could be ignition but why does it run when cool and only badly when air temp is hot. I ran for more than 30 minutes (stopped twice for refueling) without so much as a hiccup in morning. In the evening of same day on very next flight it started to act up. Air temp was 10+ degrees hotter. Going to change out the plug though.

Re: DLE35ra having fits
 

BBBair: Forgot to mention have a fuel fliter(cleanable) just before carb. Found zip in it. Also, have clamps on every fuel line connection and no air leaks. Although never checked aat the inlet tube which also apparently has been found to be leaking.

So, after reading a LOT of stuff regarding the DLE35ra on several forums, it is apparent that vaporization IS an issue with this engine. Partially because muffler is right at the carb. It is a must to have LOTS of air outlet. Even more than the usual 3 to 1 it seems. I am going to try this first as I have just, if even, a 3 to 1 ratio.(Didn't want to hack out the whole bottom of the cowl. Sort of beats the scale look but so does a crash due to an over heating engine. So, out will come the dremel tool again!!!!
I will keep everyone posted as to what develops but unfortunately it will be Monday at the earliest now as I had to keep peace in the family and go to the camper for the weekend. Wouldn't let me bring the plane LOL.

Re: DLE35ra having fits
 

Pressurizing the tank doesn't find any leaks on the clunk line inside the tank. As the fuel level comes down "3 to 4 Mins into the flight" your words. it exposes the hole in the clunk fuel line and you start sucking air.

Re: DLE35ra having fits
 

Good point. Oh god. Pull out the tank!!

Re: DLE35ra having fits
 

Have you tried flying it without the cowl to see if it is a heat issue?
Also, can you make up a heat shield to go between the muffler and carb?

Just a couple of ideas.

Good luck.