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3W-106 starting issues

Old 04-23-2007, 08:28 PM
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kkling77
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Default 3W-106 starting issues

I have a 3W-106 TOC engine that has never had any problems starting until the other day. This engine has always popped on the third or fourth flip when chocked and then started about 5-6 flips later with the choke off. I brought it to the field this weekend and found that it would still pop on the third or fourth flip, and start about 5 or 6 flips later but it would only run for about 3-5 seconds before quitting again. The engine would re-start on one flip and again run for 5 to 6 seconds before quitting. Usually on the third attempt it would continue running and have no issues throughout the rest of the flight. The needles are set fine (not too lean on the low end) and the engine would perform great throughout the throttle range. The only thing that has changed was that I replaced the ignition battery. I was using a 4.8V 1500MAh NiCD battery and went to a 4.8V 1850 MAh NiMH battery. I wouldn't think that this could create a problem, as I use a NiMH battery on a 3W-150 ignition that I have and don't have any issues. I haven't changed the fuel line yet, as I would think if it were an air leak in the fuel line than it would not run as good as it does. Anybody seen this before or have any suggestions? Thanks for the help.
Old 04-23-2007, 11:55 PM
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Tired Old Man
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Default RE: 3W-106 starting issues

Carb screen filled up with crud, blocking fuel supply? It's getting enough gas to pop but not enough to run, right? Either stoppage or a leak.
Old 04-24-2007, 12:34 AM
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ram3500-RCU
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Default RE: 3W-106 starting issues

I had a different brand engine with the same symptums and it was indeed the carberator screen. I would start there.
Old 04-24-2007, 01:25 AM
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torquen
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Default RE: 3W-106 starting issues

Its either a clogged screen in the carb or you need to try and open your low end about 1/16-1/8th of a turn. Sounds like you need just a touch more fuel for it to keep running.
Old 04-24-2007, 06:50 AM
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kkling77
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Default RE: 3W-106 starting issues

The engine runs great after the second or third stoppage. Idle's down nicely, has a smooth transition, and gets plenty of power. I would think if it were a carb blockage the engine would run bad all the time. If it were too lean on the low end, wouldn't it exhibit these symptoms continuously and not just on the first couple of flips?
Old 04-24-2007, 08:12 AM
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altavillan
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Default RE: 3W-106 starting issues

Not necessarily; Some people tune their engines so lean on the low side that they will hardly run till they warm up a bit. Your engine sounds like it's just a tad past lean on the low side because it takes 3 starts to warm it enough to run at all. Most aerobatic flying needs a carb set lean on the low side. So you are close. But why did it change? possibly a cloged screen, or a low speed needle needs an adjustment and try putting the battery back, goodness knows electronics have their own set of cantakerousnesses.

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