Marathon backfire/"afterfire" finally resolved

newtjl · 07-31-2019, 02:28 PM

I am hoping this may help another EZ GO Marathon Enthusiast. I have a 1991 Marathon that was backfiring or more properly "afterfiring" after hard runs. After the engine had shut down for a few seconds, the afterfire would occur in the muffler. It even damaged the baffling inside the muffler. I adjusted the throttle first to make sure the fuel was cutoff before the ignition. No change. I then checked the valve clearances which were in spec. No change. I then changed the spark plugs, they needed it. The gaps were very nearly covered in carbon deposits. This surprised me as the golf car appeared to run fine. The spark plugs did the trick. I ran it long and hard and no more afterfire! Apparently the plugs were so corroded that a fairly large amount of fuel was unburned and finding its way to the hot muffler. I just wanted to share in hopes of helping someone as I have found this forum to be invaluable in troubleshooting.

Dabble Inn · 08-01-2019, 10:51 AM

Good to know, Thanks

gotti · 08-01-2019, 10:57 AM

AlbiaKid · 08-21-2019, 06:16 AM

I planned to change spark plug, fuel and oil filters. Doing it TODAY. Hope it stops the backfiring. thanks

BoDidly · 08-21-2019, 07:29 PM

Thanks for sharing

07-31-2019, 02:28 PM	#1
newtjl Gone Wild Join Date: Mar 2019 Posts: 156	Marathon backfire/"afterfire" finally resolved I am hoping this may help another EZ GO Marathon Enthusiast. I have a 1991 Marathon that was backfiring or more properly "afterfiring" after hard runs. After the engine had shut down for a few seconds, the afterfire would occur in the muffler. It even damaged the baffling inside the muffler. I adjusted the throttle first to make sure the fuel was cutoff before the ignition. No change. I then checked the valve clearances which were in spec. No change. I then changed the spark plugs, they needed it. The gaps were very nearly covered in carbon deposits. This surprised me as the golf car appeared to run fine. The spark plugs did the trick. I ran it long and hard and no more afterfire! Apparently the plugs were so corroded that a fairly large amount of fuel was unburned and finding its way to the hot muffler. I just wanted to share in hopes of helping someone as I have found this forum to be invaluable in troubleshooting.
newtjl Gone Wild Join Date: Mar 2019 Posts: 156

08-01-2019, 10:51 AM	#2
Dabble Inn Nincompoop Club Member Join Date: Jun 2016 Location: Idaho Posts: 1,178	Re: Marathon backfire/"afterfire" finally resolved Good to know, Thanks

08-01-2019, 10:57 AM	#3
gotti Gone Wild Join Date: Dec 2015 Location: Alabama Posts: 226	Re: Marathon backfire/"afterfire" finally resolved

08-21-2019, 06:16 AM	#4
AlbiaKid Not Yet Wild Join Date: Aug 2019 Location: upstate NY and Texas Posts: 3	Re: Marathon backfire/"afterfire" finally resolved I planned to change spark plug, fuel and oil filters. Doing it TODAY. Hope it stops the backfiring. thanks

08-21-2019, 07:29 PM	#5
BoDidly Not Yet Wild Join Date: Jul 2019 Posts: 17	Re: Marathon backfire/"afterfire" finally resolved Thanks for sharing
BoDidly Not Yet Wild Join Date: Jul 2019 Posts: 17

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