FWIW......can you actually set the H/S adjustment so that it is in fact "Excess Rich" on an up/line??.......just to "Prove" that fuel starvation is NOT the cause??........again FWIW

How old are the front dump cans on there? If they are well used you might want to switch out to the exhaust system on the 120 that runs good to rule out plugged cans, I know it's a pain but something to think about.
FWIW

the cans are almost new, I think it's just regulation H or L can help

Question and seeking advice.....

New DLE-120 with about 10-20 flights on it....recently I have come upon this issue:

Comp-ARF Extra....Starts fine, runs great on ground......can fly 15 minutes in straight and level flight just circling the air field....BUT when I start to fly aerobatics and do a sustained negative G ...the engine quits at about the 8 min mark.

I have changed the clunk, new fuel lines, installed a new fuel tank, checked the cooling, plenty of intake air and exhaust area......new ignition, new spark plugs, checked the timing....I have tried everything including cleaning the carb and reeds.......however:

My next step is to purchase a Walbro Carb and try that...? I have had 5 DLE-120's and have had some issues with them failing (Hobbico has made good on warranty issues)

I have a NIB DLE-120 and went to check which carb it has and its a DLE Carb, I have been told that if I replace the DLE CARB and go with a Walbro my troubles will go away????

Thoughts?

P.S....yes I checked the gas, and run REDLINE 32.1

Look up ways to run the carb vent inside the fuse as I'm to lazy at the moment to give the full routine. There is a trick to solder a tube to the carb plate and route the vent into stagnant air to test if it's a cowl pressurization issue. You ruled out several common problems so this is worth a shot. Then toss a carb at it...

Originally Posted by KMatch

Look up ways to run the carb vent inside the fuse as I'm to lazy at the moment to give the full routine. There is a trick to solder a tube to the carb plate and route the vent into stagnant air to test if it's a cowl pressurization issue. You ruled out several common problems so this is worth a shot. Then toss a carb at it...

I never thought about that......easy to try ---I will give it a shot! Thanks!

I believe the 120 has the nipple already you just have to run the line.. I’ve seen guys use an old pill bottle with holes drilled in it also

Originally Posted by 3DJP

I believe the 120 has the nipple already you just have to run the line.. I’ve seen guys use an old pill bottle with holes drilled in it also

Yes mine has the nipple.....just run a line back inside the fuselage? Need some more info on the ...what/how/when/why on all this.


Again my issue is on a upline, then negative G PUSH maneuver the engine quits...all fuel lines, and tank have been replaced.

Swapping a standard clunk for a filtered clunk has been known to reduce air bubbles and also lead to more consistent running. Just another option to check.

When a plane is in flight there are pressure differences inside the cowl due to airflow. A change in heading, speed, and such can cause a change in pressure that effects the diaphragm in the carb. While this isn't likely the issue in your case, it's a quicker and cheaper test than buying and waiting on a new carb. And it's a bonus if it actually helps. Putting the hose inside the fuse reduces the potential for changes in pressure.

If your plane dies in one maneuver consistently, you likely have a carb needle issue or even an ignition issue where a connection is tweaked from a directional g force. Give all your wires a wiggle test on the ground while running to check this including the spark plug wire.

"IF" you can tackle carb repairs, tweaking the popoff pressure by the SWAG method may help (scientific wild assed guess). Don't attempt this unless you are prepared to replace the carb!! You can pull the diaphragm cover and increase the pressure an unknown amount in the name of science by stretching the spring. Also this is the time to verify the needle arm height. Typically when no tools are present many carbs can be "close" to spec when the 2 fingers opposite the needle are flush with the nearby carb body next to them. Removing this assembly and tweaking the spring a tiny amount longer can increase the popoff pressure which may reduce sensitivity to outside pressure changes. It's tricky to reinstall these parts so use caution as the springs have been known to be found in nearby states once they escape your hands. I'm joking of course! In reality, you'll likely NEVER see this spring again and only suspect it's in another state! There was a Twilight Zone episode devoted to this I believe... Like I said, this isn't for the light hearted and not to be messed with if you don't already have a replacement carb on speed dial. But it IS a good learning experience, and making a problem go away is an ego boost when these experiments actually work.

Any changes in pressures and possibly even a hose being routed into the fuse MAY result in the need to retune the needles. Be aware of this.

I had a DLE 120 that would die similar to yours. I went to a Walbro and the problem persisted. I never could figure it out and I tried and tried...good luck!

Nothing unique about its installation or use.

Just to clarify, are these dying problems you 2 are talking about at high or low throttle? Negative Gs just might be "slugging" the engine due to G forces forcing raw fuel into it in a "lump" rather than vaporized. As much as we prefer to see a fine "mist" of fuel, the fuel makes it to the combustion chamber in a rather sloppy manner and in a negative maneuver this may be dumping more liquid than vapor and washing down the plugs. That's my theory, anyway. And if the throttle is closed at this point it really complicates the issue --- IF this holds any water at all...Then again, it might be that loose doohickey next to the thingamajig. Just thinking things through at the moment.

Thank you all for the replies.....I am on my 3rd DLE-120 on this particular airplane...all replaced under warranty--I think its time to bite the bullet and buy a DA-120.

I could buy a Walbro but maybe its time to stop throwing money at it....sell it and the NIB DLE-120 I have in my stash and and just order a DA.

Originally Posted by FGNewbie

I had a DLE 120 that would die similar to yours. I went to a Walbro and the problem persisted. I never could figure it out and I tried and tried...good luck!

Nothing unique about its installation or use.

Think I may just order a DA-120.....and be done with it!

To have issues with 3 engines on one plane hints to me another engine isn't likely to solve the problem. DAs are good, but only as good as their supporting system and it sounds like you have a bug outside of the engine you're just not catching.

RKO...honestly that’s what I did...just bought a DA. I’ve seen many DLE 120s that run great and I have a 111, a. 170, and 222. For whatever reason this one couldn’t do everyday iMac figures without sputtering. Good luck

Maybe neither one of us knows what we’re doing?