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1994 Jeep Laredo misfires/backfire

Tiny
JEEPFACE86
  • MEMBER
  • 1994 JEEP GRAND CHEROKEE LAREDO
  • 5.2L
  • V8
  • AWD
  • AUTOMATIC
  • 156,000 MILES
I have a 1994 jeep grand Cherokee Laredo V8 5.2, I replaced spark plugs, and spark plug wires and now I'm Getty a popping sound out the tailpipe, misfires or backfire I don't know which one or if its either one. It was doing the the popping sound out the tailpipe occasionally once a week while in transit. Now its doing this when I crank and run the jeep, it only seems to it while in idle, and while I'm driving only between 100-2000 rpms, above 2000 rpms it does not pop or misfire or backfire. Any help? Please? Need it desperately
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Sunday, March 29th, 2015 AT 12:08 PM

11 Replies

Tiny
DR LOOT
  • MECHANIC
  • 2,311 POSTS
I would check the firing order first of, all see attached exhibit
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Sunday, March 29th, 2015 AT 8:17 PM
Tiny
JEEPFACE86
  • MEMBER
  • 7 POSTS
Okay, I will do that in the am, I followed the order that the old lines did, I had it in the shop about 8 months for reg maintenance and tune up and I looked at this diagram off the jeep forum website and this is not the order they are in? But I followed the order the previous mechanic had done? That arrow on the distributor does that mean the distributor turns once it goes on or does the arrow mean you follow that direction in putting on the wires?
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Sunday, March 29th, 2015 AT 8:28 PM
Tiny
DR LOOT
  • MECHANIC
  • 2,311 POSTS
Greetings: the arrow indicates the direction of the movement of the distributor to assist you in organizing the firing order correctly, start at number one and work your way around. Also make sure that the screws of the cap are lining up with the corresponding numbers
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Tuesday, March 31st, 2015 AT 8:30 AM
Tiny
JEEPFACE86
  • MEMBER
  • 7 POSTS
I feel real dumb lol its fixed, connections correct at distributor I had the no. 1 cylinder wire on the no.3 cylinder sparkplug, switch those front two on the rh-side and its running great! Thanks for all the help with
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Tuesday, March 31st, 2015 AT 10:25 AM
Tiny
JEEPFACE86
  • MEMBER
  • 7 POSTS
Dr. Loot I have another brain stomper, I replaced my fuel pump about 3months ago in my drive way, ever since I fixed the misfire issue the other day, the past two days every time I stop somewhere and cut it off and get back in to leave it just turns over, and over and it wouldn't fire, the first time it happened I sat at the gas station for 3 hours before I crawled underneath and checked the fuel filter, and then checked fuel pump wire connection, I unplugged the wire harness and blew in it plugged it back in and it fire rite up. What would cause this? I have to go underneath and unplug and plug in every time I stop. What gives?
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Wednesday, April 1st, 2015 AT 6:15 PM
Tiny
DR LOOT
  • MECHANIC
  • 2,311 POSTS
I'm assuming that you removing the feed line to fuel filter, in other words, the in line of the filter and not the out line? If that is the case the fuel filter might be plugged in you are relieving the pressure in the filter which is causing the vehicle to start back up. Remove the fuel filter and tell me if it's plugged, we will continue from there.
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Wednesday, April 1st, 2015 AT 9:34 PM
Tiny
JEEPFACE86
  • MEMBER
  • 7 POSTS
Dr Loot, the fuel filter was never unplugged. All I did was check to see if the filter was was still connected, I unplugged the actual wire connection to the fuel pump that sends electric power to the actual fuel pump unit.
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Thursday, April 2nd, 2015 AT 11:03 AM
Tiny
DR LOOT
  • MECHANIC
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So if I understand you correctly you had no power going to the original connection to the fuel pump, so you jump started the fuel pump is that correct?
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Thursday, April 2nd, 2015 AT 8:56 PM
Tiny
JEEPFACE86
  • MEMBER
  • 7 POSTS
Yes, I unplugged the power connection from the fuel pump unit, it comes out over the fuel tank and runs beside the fuel filter, and plugged it back in, cranked the iginition and it started, and today I was driving down the road and had my foot on the accelerator and all the sudden rpms starting dropping let my foot off the accelerator put it back on and it jumped back up, idk what is going on.
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Thursday, April 2nd, 2015 AT 9:13 PM
Tiny
JEEPFACE86
  • MEMBER
  • 7 POSTS
The fuel pump was connected but each time having to unplug&plug back in
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Thursday, April 2nd, 2015 AT 9:14 PM
Tiny
DR LOOT
  • MECHANIC
  • 2,311 POSTS
Did you check the fuel filter to see if it had a restriction?
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Monday, April 6th, 2015 AT 9:02 PM

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