Lindsay Todd Posted July 24, 2015 Share Posted July 24, 2015 One of my DLE 20's has a problem, it came around during a session flying nicely and then suddenly the throttle would not close so had to fly around till the tank emptied and the motor cut from fuel starvation. Back on the ground I expected to find a fairly simple fault such as a servo failure or throttle linkage broken or an obvious mechanical issue on the carb but a basic inspection seemed to indicate that everything was normal. I have subsequently checked that the plug is working and has a spark, that is fine so the CDI is at least generating a charge and the plug seems to be working. The tank a fuel line is clear and has good flow to the carb , pressure line is free. I then tried to re start the motor and could not even get a pop, checked the battery on the ignition and that is fine. next swapped the CDI unit for one off another motor known to be good and tried starting again and again not a pop so it feels like a carb internal issue but before I now proceed with open carb surgery has anyone else had and solved a similar problem? cheers Linds Quote Link to comment Share on other sites More sharing options...
Mark Hancock Posted July 25, 2015 Share Posted July 25, 2015 Had a slightly different problem with mine. When you throttled back it would hang on to the revs for about a minute then go down to idle. Also it was very hard to start when warm. Stripped down carb and cleaned .Was ok for a few weeks and problem came back. Got a new carb from Just engines problem solved. Its the WT644 that fits the DLE 20. Hope this may be of some help. Quote Link to comment Share on other sites More sharing options...
Mark a Posted July 25, 2015 Share Posted July 25, 2015 More likely than not its an air leak the carbs on these things are cheap and nasty. Quote Link to comment Share on other sites More sharing options...
Lindsay Todd Posted July 25, 2015 Author Share Posted July 25, 2015 Thanks guys all helpful stuff as ever Linds Quote Link to comment Share on other sites More sharing options...
IanN Posted July 25, 2015 Share Posted July 25, 2015 There's a very informative piece on improving the reliability of these carbs here **LINK** Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 25, 2015 Share Posted July 25, 2015 try a new set of carb diaphragms. They go crispy after a while and don't work properly. This is especially a problem if you don't run the carb dry at the end of the day Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted July 25, 2015 Share Posted July 25, 2015 Am I missing something here, Jon? Is what you say peculiar to DLE carbs? On the manuals for both my OS 60 &33 GTs they expressly say "Fill the carburetor with fuel at the conclusion of a day's flying - if the engine is stored without filling the carburetor with fuel the inside parts will dry out and not work properly at the next running." These are Walbro carbs I know, and I don't know what DLE uses. However, usual rules apply for laying up when the engine is not used for "a long period" (more than a year) the manual concludes, outlining what action to take. Quote Link to comment Share on other sites More sharing options...
Lindsay Todd Posted July 25, 2015 Author Share Posted July 25, 2015 Thanks for all the help guys, the carb has just be taken off and and obvious problem is the culprit The screw that secures the brass butterfly to the pivot arm had backed off allowing the butterfly disc to flap around causing dramatic changes if fuel and airflow. the cure a little red threadlock and screw it back down but you need to do this with the butterfly in the fully closed position so that you maintain full movement in the body. I consider myself fortunate as had the screw come out then it of course would have been ingested into the engine making it little more than a shelf ornament. Anyway all is now well and she runs like a champ again. Linds Quote Link to comment Share on other sites More sharing options...
Lindsay Todd Posted July 25, 2015 Author Share Posted July 25, 2015 Jon, I have always ensured diaphragms are kept lubricated to prevent the problem you mention. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted July 25, 2015 Share Posted July 25, 2015 How do you lubricate them. I am wandering towards the spark side and picking up knowledge. Quote Link to comment Share on other sites More sharing options...
Mark a Posted July 25, 2015 Share Posted July 25, 2015 I would think the oil in the fuel would keep any diaphragms lubed up in a carb. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted July 25, 2015 Share Posted July 25, 2015 Yes quite Mark, I think that's why OS gives the guidance it does. I was really waiting for Jon to come back and reply to my query about his statement about running the carb dry at the end of the session. That's clearly the case with glow engines. I just don't want to act on such suggestions unless there is a good reason for it. Hopefully, we are not missing something here. Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted July 25, 2015 Share Posted July 25, 2015 was that the engine on your Sports Cruiser? I know you had a dead stick on an earlier Greenacres do. Quote Link to comment Share on other sites More sharing options...
Geoff S Posted July 25, 2015 Share Posted July 25, 2015 I thought it was normal practice not to run petrol engines dry and to keep fuel in the tank so that the diaphragm stays wet. After all you don't turn of the fuel in your car nor drain the tank I flew my Thunderbird sports model which has a Zenoah 26 for the first time in about a year a couple of weeks ago. There was still fuel in tank but after a bit of spinning with a starter it eventually ran just as well as it always did once it cleared (I assume) the oil residue from the crankcase left once the petrol has evaporated. I have had old motor cycles to restore in the past and stale petrol has a very distinctive smell and any filters have to be cleaned thoroughly or replaced because a laquer builds up on them. That only applies to an engine that's been standing for years (even decades) rather than months. Geoff Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 25, 2015 Share Posted July 25, 2015 Its all gone a bit mad in here! Anyway, the long and the short of it is that petrol will attack the rubber diaphragms and ruin them. You are supposed to run the engine out of fuel to prevent this. If this is in opposition to OS's instructions then that is most strange as I have spoken with tillotson and walbro, as well as a friend who runs a tree cutting business and is a stihl chainsaw repair dealer and they all say to run the fuel out... Don't shoot the messenger! Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted July 25, 2015 Share Posted July 25, 2015 Yes Geoff I agree with you. The correct advice seems to be not to drain the petrol carby at the session end for lube purposes which seems clear commonsense. Just wanted to avoid duff hearsay that could lead to problems. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted July 25, 2015 Share Posted July 25, 2015 That's confused me even more then, Jon! Quote Link to comment Share on other sites More sharing options...
Lindsay Todd Posted July 26, 2015 Author Share Posted July 26, 2015 That's the one Paul, although that was down to the clunk line coming off in the tank. She will be back at the next Greenacres event now. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted July 26, 2015 Share Posted July 26, 2015 Sounds to me like both versions are correct, leave fuel in and it attacks the rubber, leave dry and the wafer thingy dries out n cracks, so they need checking now n again, I use petrol garden tools every day I never run em dry too much faffing, now n again you replace diaphragm sets. John Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 26, 2015 Share Posted July 26, 2015 The solution to the problem is the aspen alkylate petrol. It are designed to not attack the rubber parts so you can leave the fuel in. As the fuel has almost no smell it also wont stink the car out as well Quote Link to comment Share on other sites More sharing options...
.. Posted July 26, 2015 Share Posted July 26, 2015 About time someone invented a glow/ compression ignited engine that could just be oiled up and left without issue, just a thought .......... Quote Link to comment Share on other sites More sharing options...
cymaz Posted July 26, 2015 Share Posted July 26, 2015 A petrol carb with a drain vent ? Open the vent blow through the feed line...job done Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted July 26, 2015 Share Posted July 26, 2015 I know this is nothing to do with the mechanical problem that caused the DLE problems but carb problems/failures can be a pain on petrol engines .A lot of the problems with petrol carbs seem to have worsened since the fuel manufacturers started using ethanol in the fuel. It is corrosive ,hygroscopic and attacks all manner of plastics , rubbers and metals. I have tried both methods in my petrol garden tools and models ,draining and leaving wet but have had problems either way.Most common problem is the diaphragm failure but have also had problems with tank bungs becoming hard and cracking This is not a problem if engine left for a week or so but if its left for a few weeks or layed up for winter theres nearly always a problem. I recently tried some Fuel stabilizer bought at the local lawn mower repairer. Briggs and Stratton Link have developed this additive to combat the effects of ethanol damage and water damage due to the ethanol absorbing moisture from atmosphere, in engines and fuel systems . I have also tried it in a gallon of glow fuel to see if it helps reduce engine corrosion during lay ups . Not expensive £4 ish treats about 10 gallons and worth a try . Edited By Engine Doctor on 26/07/2015 10:50:43 Quote Link to comment Share on other sites More sharing options...
cymaz Posted July 26, 2015 Share Posted July 26, 2015 Posted by Engine Doctor on 26/07/2015 10:44:50: I know this is nothing to do with the mechanical problem that caused the DLE problems but carb problems/failures can be a pain on petrol engines .A lot of the problems with petrol carbs seem to have worsened since the fuel manufacturers started using ethanol in the fuel. It is corrosive ,hygroscopic and attacks all manner of plastics , rubbers and metals. I have tried both methods in my petrol garden tools and models ,draining and leaving wet but have had problems either way.Most common problem is the diaphragm failure but have also had problems with tank bungs becoming hard and cracking This is not a problem if engine left for a week or so but if its left for a few weeks or layed up for winter theres nearly always a problem. I recently tried some Fuel stabilizer bought at the local lawn mower repairer. Briggs and Stratton Link have developed this additive to combat the effects of ethanol damage and water damage due to the ethanol absorbing moisture from atmosphere, in engines and fuel systems . I have also tried it in a gallon of glow fuel to see if it helps reduce engine corrosion during lay ups . Not expensive £4 ish treats about 10 gallons and worth a try . Edited By Engine Doctor on 26/07/2015 10:50:43 Too early for any conclusions on your fuel stabiliser ? Edited By cymaz on 26/07/2015 11:23:50 Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted July 26, 2015 Share Posted July 26, 2015 Posted by Justin K. on 26/07/2015 10:04:55: About time someone invented a glow/ compression ignited engine that could just be oiled up and left without issue, just a thought .......... They have, it's the Enya 180 gx, but not cheap at £600 plus £50 for the oil... Quote Link to comment Share on other sites More sharing options...
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