muffler hangers caught fire -

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post #1 of 6 Old 09-13-2011, 11:56 PM Thread Starter
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Location: Bakersfield
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muffler hangers caught fire

I have a 1991 4.0 that has been a pain in the butt this last month. im a newb to jeeps so please feel free to correct me.with that said as of now my exhaust pipe runs really hot to where the floor board is hot as hell and at one point the rubber hangers holding the muffler caught fire. I had a clogged cat but changed that and the muffler too. after driving 20 miles at 65 got home and the rubber hangers melted off. I was told my jeep was running rich. here's a list of everything I have did to it this month.

spark plugs
spark plug wires
IAC valve
exhaust manifold(had a crack)
fuel filter
o2 sensor

my problem is that I'm getting 5 to 10 mpg and i can really feel the heat from under wial driving . the thing that throws me off is that it drives great and has power .

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post #2 of 6 Old 09-14-2011, 07:24 AM
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1990 YJ Wrangler 
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cat converter backed up maybe

Warning: This poster has infinite knowledge of useless information and redneck tendencies. Use info at your own discretion. :wave:
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post #3 of 6 Old 09-14-2011, 07:30 AM
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1991 YJ Wrangler 
Join Date: Sep 2011
Location: Blairsville
Posts: 14
Wow, that sounds like a rough problem. Why not replace the whole exhaust with something more free-flowing while you're down there? Shouldn't be too expensive, you have to replace the hangers anyway, and the cherry on top is the sound.
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post #4 of 6 Old 09-14-2011, 09:03 AM
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1988 YJ Wrangler 
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Location: Rio Rancho NM
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Running rich will kill your new cat converter fast.
You need to find the source of the over rich condition fast.
Almost any engine sensor can cause it to run rich as can a leak in the exhaust before the O2 sensor.
What fuel pressure do you have?

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post #5 of 6 Old 09-14-2011, 12:09 PM Thread Starter
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well all this happened a little after I purchased a new cat and muffler so the muffler shop would not replace my clogged cat because it was my fault the jeep was running rich. so since I just got it smoged I took the cat off and welded a straight pipe to the muffler. the jeep runs good but there's no back pressure on the tail pipe. today my buddy's coming over with a fuel pressure tester so ill have that figured out today.
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post #6 of 6 Old 09-14-2011, 12:10 PM Thread Starter
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oh an it still gets really hot underneath but I try not to drive more then a 20 min drive lol
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