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2002 Sportsman 700 backfiring
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My sportsman started backfiring when releasing the throttle after running with wide open throttle. It idles fine. I have changed the oil, air filter, and have fresh gas.
I adjusted the throttle cable according to the manual and performed the ETC SWITCH test. The etc switch failed the test. It moves freely and the contacts are not touching. When the contacts do touch, the engine does not stop. The wires and connections appear to be ok...Does the switch need to be replaced or is there something else that would be causing the backfire?
 
Posts: 9 | Registered: July 21, 2010Reply With QuoteReport This Post
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I doubt the ETC is causing the back fire. Do you have an exhaust leak? An exhaust leak will let air into the exhaust and the hot gases might be igniting it.


2004.5 Mossy Oak 700
2007 Stealth 800
 
Posts: 11947 | Location: Louisiana | Registered: February 25, 2004Reply With QuoteReport This Post
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That very well could be the problem. I did just replace the donut gasket and springs on the exhaust manifold. It does not sound like it is leaking. Is there a caulk or something that I could use to better seal the pipe connections?
Also, regarding the etc switch. Shouldn't the engine die when the contacts touch? Is this a separate problem?
 
Posts: 9 | Registered: July 21, 2010Reply With QuoteReport This Post
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The Exhaust donut at the engine made my 700 backfire. Stopped when I installed a new donut.
Did not sound like it was leaking.
 
Posts: 2357 | Location: S.W. Az | Registered: May 13, 2009Reply With QuoteReport This Post
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quote:
Originally posted by jrw227:
Also, regarding the etc switch. Shouldn't the engine die when the contacts touch? Is this a separate problem?

You might need to ask this question a different way. I'm not sure what you're getting at.

How well did you clean the pipe when you installed the new do-nut? You could use a high temp sealant, but if there are parts of the old do-nut left on the pipe, it may not be sealing like intended. There should also be a spring and a stop further down the pipe that should be in place and keeping the pipe from moving and causing a leak.


2004.5 Mossy Oak 700
2007 Stealth 800
 
Posts: 11947 | Location: Louisiana | Registered: February 25, 2004Reply With QuoteReport This Post
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Below is a quote from the OEM manual regarding ETC operation.
================================================================
ELECTRONIC THROTTLE CONTROL
(ETC) SWITCH
ETC Switch Operation
The Electronic Throttle Control (ETC) system is designed to stop the engine of an ATV in the event of a mechanical problem with the throttle mechanism. The ETC switch is mounted
independently of the throttle actuator lever inside the throttle block assembly. This is a normally closed switch, and is held in the open position (contacts are separated (as shown below) by throttle cable tension. The contacts are open" during normal operation regardless of throttle lever position. In the event of a mechanical problem in the throttle mechanism (cable tension is lost), the switch contacts close, connecting the black wire to ground, which prevents ignition spark. This is the same as turning the key or engine stop switch “OFF”.

NOTE: Test the ETC switch at the harness connector. ETC will not activate unless there is
throttle plate movement off of “zero” detected by the ECU. Adjust throttle cable freeplay (ETC switch) and make sure throttle mechanism is functioning properly before testing the switch. Refer to Maintenance Chapter 2 for cable adjustment procedure.

ETC Operation Test
1. Remove throttle block cover by carefully releasing all tabs around edge of cover.
2. Place transmission in neutral and apply parking brake.
3. Start engine and open throttle lever slightly until engine RPM is just above idle speed.
4. Hold throttle cable with fingers at point “A” as shown below and release throttle lever. If the ETC system is functioning properly, the engine will lose spark and stop.
=======================================================================

If what I think you're asking, the throttle cable would have to be very loose at idle to kill the engine. The ETC is kill the engine if the throttle was stuck open. I would raise the idle with the thumb throttle to like 2,000 rpm and with a needle nose, pinch the cable so the idle stays high and release your thumb from the throttle. If it doesn't die, your switch might not be operating as intended.


2004.5 Mossy Oak 700
2007 Stealth 800
 
Posts: 11947 | Location: Louisiana | Registered: February 25, 2004Reply With QuoteReport This Post
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Thank you for your response.
I am clear on exhaust remedy. I will take the donut out and clean the pipe to make sure there is a good connection. If that doesn't work I will try some sealant.
With regard to the etc switch. I just happened to test it according to the manual instructions as I was looking for a solution to my backfiring problem. The manual says that the engine should die when the contacts in the etc switch touch each other. This did not happen. The engine kept running. Assuming this is unrelated to my backfiring problem, is it something I need to worry about? And, what do I need to do to fix it?
 
Posts: 9 | Registered: July 21, 2010Reply With QuoteReport This Post
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Looks like I copied and pasted that out of an EFI manual. All my carb manuals are secured so I can't copy and paste. If you're absolutely certain the ETC isn't function, I would replace it. It is a safety mechanism. But I think to determine it is in fact bad that you perform the ETC Operation Test above. Get the engine off of idle for the test.


2004.5 Mossy Oak 700
2007 Stealth 800
 
Posts: 11947 | Location: Louisiana | Registered: February 25, 2004Reply With QuoteReport This Post
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I will check into it further when I get the exhaust taken care of. I did perform the test according to the polaris manual. The etc switch appears very basic (a basic kill switch) on the inside and nothing appears broken. The wires are not burnt and the contacts are not corroded. It does not seem that the problem would actually be inside the switch housing but somewhere else along the wire or where it leads to. Any ideas other than replacing the switch?
 
Posts: 9 | Registered: July 21, 2010Reply With QuoteReport This Post
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i wouldn't worry about an occasional backfire on decel, but doing it all the time is not right. check your y pipe at the intersection [closest to the head] for a crack or a failed weld, i've seen that happen a couple of times over the years.......stroker


it is important to know what you know, but far more important to know what you don't know......
 
Posts: 2018 | Location: west central mi. | Registered: May 03, 2005Reply With QuoteReport This Post
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Just got done cleaning the connections and reinstalled with gasket sealant. The backfiring continues on deceleration. It doesn't start backfiring until the machine slows down to about 15 mph or so...Too hot right now to check the y pipe.
Maybe I should just replace it anyway, being 8 years old and rusty it may have a leak that I won't detect.
Two questions: Will an exhaust leak further back in the system cause a backfire? Where is a good place (inexpensive) to get a y pipe and exhaust pipe other than the dealer?
 
Posts: 9 | Registered: July 21, 2010Reply With QuoteReport This Post
rotaredoM
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The ETC will kill the motor if you don't get back on the throtle. If that is what is happening you need to adjust the throttle cable.

I had a carb 700 two VERY common problems. The carb boot is ripped and it is running lean or the exhaust pipe is cracked at the U-turn right off the head.

Most likely is carb boot.


Remember Illegal tapping of news media, Benghazi, one American and 4,000+ Mexicans killed by Fast & Furious, the IRS scandal, the NSA eavesdropping, and the takeover of your healthcare! Now the VA scandal, turning Texas & Arizona into refugee camps amnesty for illegals. I'm gonna need a bigger Sig.
 
Posts: 10423 | Location: Mexazona, U.S.S.A | Registered: October 18, 2003Reply With QuoteReport This Post
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Originally posted by YnotAZ:
The carb boot is ripped and it is running lean or the exhaust pipe is cracked at the U-turn right off the head.

This is the rubber carburetor adaptor between the carburetor and head. Ynot is right, cracking is a common problem. Since you didn't mention it was running bad, I didn't suggest it. It may be a small enough tear to not cause any other issues, but chances are it's leaning out the motor and causing your backfire.


2004.5 Mossy Oak 700
2007 Stealth 800
 
Posts: 11947 | Location: Louisiana | Registered: February 25, 2004Reply With QuoteReport This Post
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if your y pipe is bad replace it with the 800 header type. lots of us have done that and it is a better design. some modifications to the heat shields may be necessary, but very doable and yeilds good results.......stroker


it is important to know what you know, but far more important to know what you don't know......
 
Posts: 2018 | Location: west central mi. | Registered: May 03, 2005Reply With QuoteReport This Post
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You guys really know your stuff! The carb boot has a crack in it. I have one on order now and will let you know after I put it on if it solved the problem. Thank you very much.
For future reference if I ever need to replace the y pipe, what is the 800 header type and where can I get it?
Also, regarding the etc switch. The manual says that when the two contacts inside touch, it should kill the engine. This does not happen when I do the test. As I said before the switch and wires appear to be ok. I would like to know before unnecessarily replacing the ninety dollar switch is if there is a more likely culprit causing the engine not to quit when the contacts touch.
 
Posts: 9 | Registered: July 21, 2010Reply With QuoteReport This Post
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I don't know that you could get an 800 header that isn't two piece. The two piece superseded the one piece at least 3 years ago if not longer. As the to ECT, the only thing I could see beside the switch failing is a grounding issue.


2004.5 Mossy Oak 700
2007 Stealth 800
 
Posts: 11947 | Location: Louisiana | Registered: February 25, 2004Reply With QuoteReport This Post
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Yep been there done that with the carb adaptor, donut on stock Y manifold and broken 1 peice 800 pipe.
Also had a problem keeping the manifold bolts tight even with 271 loctite.


Sp600/700/(800 most) exhaust gasket ‘donut’ is NAPA part # 31360, Murray’s/ O’Riely’s Auto # G783B-S for around $9.

The one piece sp800 dual header pipes from 2005 to 2007 on the sp800 or if added as a mod to 600/700s is known to be faulty.

I got the whole kit (P/N 2876216) with the newer sp800 large heat shield for $141 shipped from Babbitt's. The kit was $110 and it came with everything, a head gasket (normally $21 form Polaris), 3 springs, 2 exhaust donuts (separately $20 ea.) bolts and washers for pipe and heat shield, the shield was and extra $15 not included in the 'kit'.

The paperwork stated it is to fix existing pipe breakage problems experienced with previous 1 pc 800 pipes where it goes from 2 into one.

“This kit addresses the pipe failures at the rear of the collector (where the twin pipes adjoin to one pipe”.

If you buy from the parts list from 2008 or newer you will be buying each piece separately at a greatly increased price, so order the ‘Kit’ from the 2005 or 2006 sp800 revised (superseded) part number.

And our Polaris "savings" from the previous bad design are from buying the kit as opposed to buying separate pieces as the 2008 and up microfiche indicates (now all in one 'kit').


Jim


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Posts: 932 | Location: S.E. Michigan | Registered: August 30, 2004Reply With QuoteReport This Post
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jrw227, my 2001 sportsman was doing the same thing. After I had checked everything else I replaced the sparkplug and what do ya know, no more backfire. Mine was running fine otherwise and I didn't think the plug would matter but it did. Try that and see what happens. Smile


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Posts: 233 | Location: Tn | Registered: February 07, 2008Reply With QuoteReport This Post
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