Need help: 99 Vmax 500 SX Backfiring, Won't Run

J

jmbones

New member
Joined
Nov 5, 2006
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Age
46
Location
PA
I have a 99 Vmax 500 SX, riding it all morning yesterday with no issues. Fill it up with gas, take it out later that night and it starts to back fire and smoke alot, then shuts off. It actually backfired 15 seconds AFTER it was off. Bad gas? Any ideas?
 
sounds like bad gas , probley water , buy bottle of heet fuel treatment the red bottle for 2 cycle engines try it see what happens
 
Thanks. It ran fine all day, then it just took a dump and started back firing and then eventually shut off. The only issue I could think of with the gas is it having minute amounts (a trace) of 2 stroke mix oil in the jug. I just bought the gas and filled up a jug that previously had 2 stroke mix in it. I don't think there is enough residue in it to hurt though?
 
daman said:
That would have hurt nothing....

does it seem like it could be an electical problem when it acts up???
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It could be, it's my sled but my friend was driving it when it occurred. It did seem to smoke alot more then usual before it happened. It was driving fine, he got hung up with it and after that he said it felt like it was loaded up, so I'm not really sure. We changed the plugs with new ones and it fired up and then shut down 2 minutes down the trail and back fired 15 seconds after it shut off. I havn't even had a chance to get it back to my house yet to check into it. I don't even know if it has spark yet.
 
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daman said:
Is it using a ton of oil, or it seems normal???
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To tell you the truth, it always seemed like it used alot of oil. I did have to fill it up before that trip, and it looked to be real low. Do you think it is injector related? I use the Yamalube 2 stroke oil.
 
your just going to have to get the sled home and see for your self how it's
acting,then give us more accurate info,instead of speculating all day..
 
Got it home. Seems like the coil is the culprit. Tested for spark, sometimes it was there, sometimes it wasn't. The black wire that comes out of the coil and goes to an orange wire under the dash is loose and the insulation is off right where it goes into the coil. Wiggled that wire around a little and then there was spark again. Sound about right?
 
daman said:
I would say there's a problem there,swap coils and post back..
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Gotta order one, I don't have any spares. I'll update it when I receive the new coil.
 
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