What Causes Backfire? - Snowmobile World

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USArower U My 96 AC EXT 580 efi will not start/run properly, but when you pull the rope, the pipe occasionally lets out a loud backfire. what causes this? #1 · Nov 8, 2003 My 96 AC EXT 580 efi will not start/run properly, but when you pull the rope, the pipe occasionally lets out a loud backfire. what causes this? Sort by Oldest first Oldest first Newest first Most reactions #2 · Nov 8, 2003 You said it won't start/run properly, which is it?? if it runs, or turns over, and is getting spark then the exhaust is just loading up with fuel each time you pull the rope. When it finally does spark then the unburned fuel in the exhaust system is ignited causing the backfire. #3 · Nov 8, 2003 put some new plugs...check if the old one are wet. #4 · Nov 8, 2003 sometimes it starts but doesn't run well. Most times it wont start. #5 · Nov 8, 2003 my snowmobile did that and found that it was just a dead plug. try new plugs and then try starting it with no choke, maybe ur really flooding it? #6 · Nov 8, 2003 I've seen those exact conditions when there was water in the gas. #7 · Nov 8, 2003 spark plug wires crossed??? #8 · Nov 8, 2003 1)make sure the plugs are good 2) try and make shur you're not flooding it 3) take a gas sample by draining the carbs and put the gas in a clear jar and let sit for a couple of minutes, if you see a separation in the liquid there is probably water in the gas 4) put a timing light on the #1 cylinder and find your timing marks and have someone pull it over while you check the timing 5) undo the exhaust from the headpipe and make shur Mr. Mouse didn't build a nest in your exhaust, or that the pipe isn't carboned shut. But try to temporarily start the sled with the pipe undone but if it fires shut it off and check for exhaust restrictions 6) Unplug kill switch and see if it will start and run.(Most sleds will run with the kill switch unplugged) 7) last but not least if all else fails have the dealer check the coils and the stator......Hope these help but this is what I would do for checking out the problem.....Steve #9 · Nov 8, 2003 Sno-nuts has pretty much got it all said, but don't forget the basics. Check your compression, and do a spark test. If you've been firing it up and idling alot it may just be loaded with fuel. Being an EFI model make sure any ground wires are clean and tight. #10 · Nov 8, 2003 I don't know alot about efi's, but my buddie's '95 wildcat 700 efi would act up if the battery was not fully charged. Maybe an easy fix? #11 · Nov 8, 2003 This is a battery system, is it not? I have heard that the old battery systems can be very finnicky with batteries. If the battery is not perfect, then it could run poorly, or not at all. Install new plugs. Make sure the plug boots are firmly screwed on the plug wire, hold the wire and rotate the plug boot (cap) to seat the connection. Remove old gas and start with fresh. If it still does not run, then get a new battery. #12 · Nov 19, 2003 What would happen if the plug wires got crossed? and how can you tell? #13 · Nov 19, 2003 have a 96 pantera thats yhe same motor as you. make sure your battery is full of h2o. then charge it and try. thats the most common. also put br9eya plugs in. really helps at start up. if you've never changed your plug wire ends i would recomend it. as far as crossed wires one will look ok and one wire will be tight if crossed. there is a couple other things that come to mind ,but i would do these first. hope this helps. #14 · Nov 20, 2003 plugs and gas is the first step,,,,,battery is the second good luck #15 · Nov 20, 2003

Originally posted by USArower@Nov 19 2003, 10:23 PM What would happen if the plug wires got crossed? and how can you tell? Click to expand...

Absolutly nothing. It's not a four stroke, and there is no distributor, so when one plug fires, they all fire. If you tried all the obvious stuff (gas in the tank, etc...) check to make sure that you crank has not gone out of index. #16 · Nov 20, 2003 I have a buddy with the same machine and it was doing that just after he bought it used. He took it back to the dealer, they said it was the piston rings because he had bad compression. They changed the rings and no more backfires. He still has problems with it starting sometimes though. Insert Quotes Post Reply

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