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DLE Engines Won't Start, Culprits Found

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DLE Engines Won't Start, Culprits Found

Old 04-10-2017, 11:11 AM
  #1  
djmp69
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Default DLE Engines Won't Start, Culprits Found

Not sure if this is in the right forum, but I figured I'd post a few experiences in hopes that it will help someone who is maybe experiencing similar symptoms. I titled it "DLE..." but the causes I found can affect any gas engine. Just my 2 cents...

CASE 1: Engine is a DLE 55. Has been in 3 planes so far, all with the same 4.8v battery on the ignition. Engine has a little over 400 flights on it, and was running really well up until about the end of last season. It started surging and missing at the mid-range. I figured it was most likely crud getting past the filters in my gas can and fuel lines and building up in the carb. No big deal, opened up the carb, cleaned it out. Checked my fuel tank, took out the tubing and put new tubing in, new clunk. Engine still did the same thing. The next thing I noticed, I noticed while I had the cowl off. One of my standoff bolts had broken, and another one had lost the bolt. So I figured that since the engine wasn't as secure, it was bouncing around from the exaggerated vibrations at lower rpm. I replaced the bolts. As it was the end of the season, I put it up for the winter. First time out this season, took it out, and it took about the normal number of flips on choke to pop after sitting for a few months. Revved it, everything seemed ok, there were a few misses, but I chalked that up to it "waking up" after the winter. Got about 5 flights on it, good day. That was a Friday. A few days later, Sunday, took it out, it started normally, idled great, but when I advanced the throttle, it ran REALLY rough, as if my high side was WAY rich. I couldn't understand it, because it had just run so "great" just the other day. So I go through the motions, changing needle turns, even swapping out the spark plug, checking the battery, everything was as it should be. I couldn't get it to run, and I was already frustrated by another plane not starting (that case is next), so I packed up.

The following weekend, I took the plane out again, only intention of finding out what was going on with a fresh mind on the situation. This time, the plane would not even start. "It couldn't be the battery" I thought. So just to check, I reset my needles and tried another battery. Still ran rough. Then I thought, maybe it was the master switch. Dunno why I didn't think of this before. So I connected the battery directly to the ignition module. FIRED UP STRONG! I was so relieved that my suspicions were correct, as I take great care of my engines, I was really hoping I hadn't missed something and messed it up. Then I thought, wait, now it could be the master switch OR the electronic cutoff. So I connected the battery to the master ignition switch, then to the module, engine ran great. Reintroduced the electronic kill switch, plane wouldn't even run. BINGO!!!

Now I don't know if there was something I could have done to fix the kill switch, but I don't care. Not something I want going bad when I'm torque rolling 5ft off the ground, so I replaced it and all's well now!

Case 2: DLE 30. I noticed after about 70 flights or so on a brand new engine that ran great, it would get really hard to start after two flights. Eventually, it wouldn't start at all. As this plane I didn't fly often anyway, I wasn't as proactive in trying to find out what the deal was. Ultimately, people were telling me that it sounded like the carb was clogged deep inside. I didn't believe them, but I figured I would check it anyway. I'll be honest, I started to get a carb rebuild kit, but I got lazy and just decided to get a new carb, as cheap as they are. While I was at it, I figured I'd change the reed block assembly and gaskets as well. Did all that, and guess what? Still the same problem. The engine would pop on choke but was VERY hard to get running. Even with a starter. Since it was at least popping, I knew it was getting fuel. I tried a new spark plug. I checked my tank, replaced the tubing. I tried different needle settings, mostly low end, thinking it was a fuel delivery problem. No joy. Now it WAS easier on richer settings, but still not good. So after a few weeks of this, I figured it HAS to be an electric problem. The last time I checked the battery (2000mah, 4.8v) it was good, but then I realized that was long ago, and the charger I had been using was the normal plug in the wall kind. So I decided to charge it with my Hyperion charger and watch it. Whaddya know?!? Even though my tester said the battery was at 5.3+ volts, when I put it on charge, the voltage shot up to 6.8v+, instead of the normal 5.8 or so. The charge cycle ended in about an hour or so at 500mah. Uh oh, I thought, that usually means a bad cell or pack. So just to check I put a 500mah discharge on it, and the charger immediately indicated the discharge was finished. BINGO! Or so I thought. Took the plane out, tested it with another battery that I knew was good, and no joy. Bummer. Then I thought, what if maybe it is the module, and the module messed up the battery? Tried a different module with the fresh battery, and VOILA! Plane runs great. It was only then that I remembered that when I changed the spark plug, a ring of the insulator stayed on the plug. My theory is that the break in the insulation allowed the spark to not only get to the plug, but get through the break and get to the cap and short circuit. Changed the spark plug cap on the original module, and guess what? Engine runs great. Worst case now is, I have a spare carb that's already set great plus a reed block assembly that's fine, and a "new" ignition module.

I know this might be elementary stuff for most, but hopefully these experiences might help someone who is new to gas powered craft, or anyone that just can't figure out what's going on because like me they're frustrated and just haven't checked simple things because, again, like me they focused on so-called obvious causes, or just haven't yet thought of everything.
Old 04-10-2017, 02:13 PM
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tailskid
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Thank you for sharing your solutions to two common situations!

Jerry
Old 04-18-2017, 03:00 AM
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Thanks for posting. Very informative and helpful.

carl
Old 04-21-2017, 06:52 PM
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I had an "OLD" small engine guy tell me one time... "most carb problems are electrical in nature". I think I have found that to be true in many cases!

Ken

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