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DLE20 Runs full throttle with both Hi an Lo needles all the way in??

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DLE20 Runs full throttle with both Hi an Lo needles all the way in??

Old 11-12-2015, 06:47 PM
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j_keiter
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Default DLE20 Runs full throttle with both Hi an Lo needles all the way in??

I swapped carbs from another DLE20 and was able to lean Hi needle till engine died. I'm trying to figure out what is wrong with original carb. Anybody have any ideas how fuel continues to get to engine when Hi and Lo needles are closed all the way?? I've always been gentle when seating needles for turn reference so I don't think seats are damaged. Very wierd!

Thx Jason
Old 11-12-2015, 07:38 PM
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w8ye
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The needle is not seating in the regulator side of the carb. The carb is letting fuel into the engine when it is not supposed to.
Old 11-12-2015, 08:04 PM
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ahicks
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Yep, agreed. That needle is stuck or has a piece of crud under it keeping it from closing. Fuel is going everywhere but where it's supposed to inside that carb. It needs to be pulled down and cleaned, but may not need any new parts.
Old 11-12-2015, 08:12 PM
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Truckracer
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+1 with everything said above. One other possibility, if a welch plug dislodges inside the carb (under the regulator diaphragm) it would allow fuel to flow around the needles directly to the engine. Frankly though, I would expect this to completely flood the engine but if it were just leaking, this could be the problem. Crud in the metering needle as suggested above is more likely.
Old 11-12-2015, 09:17 PM
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j_keiter
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I inspected rubber tipped regulator needle and looked at it's seat with a flashlight. Looked very clean. Welch plug looked good but don't know how to test for leaks. I went ahead and blasted carb cleaner through regulator needle hole. I'll run it again to see if anything changed. I would think that I could cut off fuel by closing Hi and Lo needles regardless of rubber tipped regulator needle.
Old 11-12-2015, 10:14 PM
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Some needles only control part of the fuel flow in the carb .... the remaining fuel flowing in drilled passages around the needle circuits. I believe they do this to make the needle adjustments less sensitive. One other possibility, could the needles be interchanged in their locations. Some carbs use the same needles in both locations, some are quite different between the L and H needle.
Old 11-13-2015, 01:48 AM
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RiverLarry
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There is a lot of truth with that statement on the L & H Truckracer R/L
Old 11-13-2015, 04:47 AM
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Also check to make sure that carb is not sucking air from a bad gasket seal which would also support Truckracer's supplemental fuel flow and the needles in the correct seat.
Old 11-13-2015, 06:24 AM
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j_keiter
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Needles have different diameters on threaded portion so accidentally switching is not an issue. From Post #1 "I swapped carbs from another DLE20 and was able to lean Hi needle till engine died." Because of this I don't think there are passages around Hi needle in a stock DLE20 carb. Another possibility is the Regulator needle is stuck open such that full pump pressure is always at Hi needle such that closing it all the way with hi pressure allows engine to run at full throttle. Perhaps there are some passages around it per Truckracer. Ugh! I'm thinking too much. When I get a chance to run again I'll post results. Jason
Old 11-13-2015, 09:22 AM
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When a gas engine gets lean enough, it will die even though there is some fuel flow. Gas / air will only burn in a narrow mixture range, leaner being quite hard to ignite with a spark and richer being much easier to ignite. I mention this to support why an engine may die even though it is getting some fuel as in when some fuel flows around the adjustable needles.

At some point, if the problems in the carb are not clear, I'd just replace the carb! For $40 or so, why mess around with a problem child carb.
Old 11-13-2015, 10:03 AM
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The regulator diaphragm if stiff and collapsed will hold a clean and good needle up and let fuel flow. Maybe a new or different diaphragm would be a good check.
Old 11-13-2015, 11:42 AM
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w8ye
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You can put 7 lbs static pressure on the fuel inlet of the carb and see if the carb holds the static pressure.

The carb should hold the pressure indefinitely as long as the engine is not moved.

A modeler at the flying field could even blow in the fuel inlet using a piece of Tygon to see if the demand regulator is leaking.
Old 11-13-2015, 11:49 AM
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Most of the engines I have checked recently have a pop off pressure between 25 and 30 pounds (some even higher) which seems to be a good range for airplane use. Get much below 20 and "G" forces start having an effect on how the engine runs through maneuvers.
Old 11-13-2015, 04:53 PM
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If all else fails, K-20 WOT or D-10 WOT rebuild kits are cheap as beans and super easy to do. Any time ive had an issue and couldnt figure it out, ive rebuilt and was happy. Just my 2 cents.
http://www.chalmersindustries.com/ is the best prices that i found.
Old 12-16-2015, 12:55 PM
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j_keiter
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stevegauth30 you nailed it. Tried to start today and kept flooding again. Pulled carb and compared dle metering diaphragm to new walbro diaphragm I had on shelf. OMG the dle was very stiff compared to Walbro. So I installed the Walbro and wham, fired right up and ran lile a champ. Not sure if it's ethanol in gas, dle quality or just age.
http://www.chalmersindustries.com/ for Walbro rebuild kits.
K20-WAT_AM $2.49 beware I think the AM stands for after market.
Product Code: K20-WAT $9.49 is genuine I think. Price reflects that.
D10-WAT $7.49 appears to only be diaphragms. No needles/springs etc.

Last edited by j_keiter; 12-16-2015 at 01:05 PM.
Old 12-16-2015, 01:27 PM
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HI Fiver Larry. We have been in Florida for about 34 days now.....love it. There is a outdoor swap meet this Saturday. Interesting about that too much fuel problem !!!!! John ...over & out.....
Old 12-16-2015, 07:23 PM
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w8ye
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Originally Posted by j_keiter View Post
stevegauth30 you nailed it. Tried to start today and kept flooding again. Pulled carb and compared dle metering diaphragm to new walbro diaphragm i had on shelf. Omg the dle was very stiff compared to walbro. So i installed the walbro and wham, fired right up and ran lile a champ. Not sure if it's ethanol in gas, dle quality or just age.
http://www.chalmersindustries.com/ for walbro rebuild kits.
K20-wat_am $2.49 beware i think the am stands for after market.
Product code: K20-wat $9.49 is genuine i think. Price reflects that.
D10-wat $7.49 appears to only be diaphragms. No needles/springs etc.
age

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