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Post by mrcollins on Apr 1, 2012 17:01:00 GMT -5
Hello. First post. I have a 2010 Jonway 50cc QMB139 that I bought new last summer and drove through the mild winter. Sitting now at ~2,800 miles, maintenance(oil,gear,air,spark,fuel filter) at 800, 1800, 2,600. Have had no problems until the past two or three weeks. It began by sputtering after about 5-10 min riding above ~30mph. Also getting harder to start. Progressively got worse. My first thought was bad gas, as I get gas at the same little gas station down the street(premium 93 octane, always). Stopped at the bank one day and could not get it to start, seemed flooded(or bad gas). Drained gas and got gas else where to replace, changed fuel filter. Fired right up! and ran good for the rest of the day no sputtering. Next day, hard to start but ran fine to visit my parents(~5 miles 1 way) and halfway back. Halfway back making a right turn, it sputtered and lost all throttle response(wanted to die with throttling), but still running with a sputter until it just died and has not started since. My troubleshooting so far:
*New gas and fuel filter *checked all air fuel lines for connection. *Took carb off, opened bowl, checked jets for clogs, drained bowls and they fill back up. *Checked valves they are at .004 *Spark plug is brown to black and wet. Tested plug cap for spark, plug in cap sparks.
Sorry for long story! Any ideas what to check or recheck? I have iridium plugs on the way, short of that I'm out of ideas. It seems(to me) to be either flooding or not sparking while plug is in the block. I can post pics and/or videos if needed. Thx
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Post by tortoise on Apr 1, 2012 17:30:28 GMT -5
Spark plug is brown to black and wet Potential issue.
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Post by mrcollins on Apr 1, 2012 18:25:30 GMT -5
Thx for quick reply. I agree, its rich. Checked vacuum line from tank petcock to intake, it's not bypassing as far as I can tell. No gas coming through when suck test it. Worked proper when I emptied gas tank too. Fuel filter and bowls are getting gas proper. Attachments:
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Post by tortoise on Apr 1, 2012 18:51:00 GMT -5
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Post by mrcollins on Apr 1, 2012 19:53:33 GMT -5
I don't have the gauge and plug adapter right to test compression. Not a exact test but getting pressure out of exhaust while turning it over. I am getting 23-24v off CDI to coil and good spark while plug is in cap and grounded to block www.youtube.com/watch?v=MgXBVlXHwrQ&feature=youtube_gdata_player Done for tonight, but will get the compression tools tomorrow... Thanks tortoise
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Post by one1 on Apr 1, 2012 21:40:20 GMT -5
Have you held the plug to the frame and turned the scooter over to see if it is sparking? If it does, then hold it to the engine head and see if it does it there as well. My scooter did the EXACT same thing to me today... bogged, died, wouldn't restart. After getting home I realized the portion of the plug connector inside the boot has came unscrewed inside. Check yours for tightness.
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Post by mrcollins on Apr 3, 2012 13:09:46 GMT -5
Thanks all. I didn't get around to buying the compression tools. However, I found the problem and my scoot is up and running. I was getting spark from the plug in cap grounded to block. After testing the voltage from CDI to coil, proved that CDI was good (~24v). I noticed the spark plug wire was arching to the frame all over the place. Luckily I had an parts scoot nearby and grabbed the coil/wire/cap unit off it and switched it out. Presto, fired right up no sputtering, runs like it did before. Not quite sure if it was the coil crapping out or the wire or the cap. Evidently, the coil wire unit was grounding out to the frame causing the sputtering and eventually the no start issue.
Thanks to all again and happy scooting
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Post by skuttadawg on Apr 5, 2012 23:01:18 GMT -5
Harbor Freight has a compression testing kit for 20 dollars as I bought one myself . Try this remove the hose on the valve cover and see if it smokes . I had a piston crack and when I went back to my dealer he did that and told me the piston may be cracked and it was dang it . Use your hand to push down on the kickstart to have a rough idea if the compression is good
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