|
|
 xj studdering problem
#871068
02/24/08 04:32 PM
|
Joined: Feb 2008
Posts: 17
OP
Need a Spot
|
need some help figuring this out. 98 xj 4.0 multiport injected automatic, starts and runns fine about 10 minutes then starts studdering, replaced fuel pump/regulator/filter assembly with no improvement. any help appreciated <img src="/forums/images/graemlins/confused.gif" alt="" />
|
|
|
Re: xj studdering problem
[Re: fulltime79]
#871069
02/24/08 05:57 PM
|
Joined: Sep 2005
Posts: 1,087
Body Damage is Cool
|
I assume that the shuddering occurs while you're driving down the road? If so, what happens if you shift the tranny into Neutral while it's shuddering? Or does it also shudder if it's been sitting still idling for 10 minutes?
1977 CJ-7, fiberglass body, AMC 360 w/ headers, DUI ignition, Edelbrock intake and Holley 4150 carb, TF999, Dana 300, 4.56 gears lockers, York air comp, 4" susp lift, 2" body lift, BFG 35" M-T tires, Megashifter, AGR pump & box, REP8000 winch.
|
|
|
Re: xj studdering problem
[Re: fulltime79]
#871070
02/24/08 05:59 PM
|
Joined: Oct 2003
Posts: 7,768
Web Wheeler
|
need some help figuring this out. 98 xj 4.0 multiport injected automatic, starts and runns fine about 10 minutes then starts studdering, replaced fuel pump/regulator/filter assembly with no improvement. any help appreciated <img src="/forums/images/graemlins/confused.gif" alt="" /> We need a much better description of "studdering".. Is this at idle only? Is this at rpm only? do you hear popping and extra noise when it happens? After about 10 minutes the system goes to a leaner mixture.. this leaner mixture burns a little better than the "choke" mixture and burnt valves show up better at this time.. Please give a more complete description.. Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />
professional bovine relocation specialist
|
|
|
Re: xj studdering problem
[Re: BigJim]
#871071
02/24/08 06:18 PM
|
Joined: Feb 2008
Posts: 17
OP
Need a Spot
|
sorry guys, heres the deal. started about three weeks ago, doesnt matter weather im driving or not. happens while ideling in the driveway, or while driving down the road at any speed. motor starts stumbling and backfiring through the intake. yesterday i replaced the pump/regulator/filter assy. started it up, let it run in the drive, about ten minuits or so it started stumbling.
|
|
|
Re: xj studdering problem
[Re: fulltime79]
#871072
02/24/08 06:45 PM
|
Joined: Feb 2008
Posts: 17
OP
Need a Spot
|
was on the way to work the other nite , ten minuits of 3o mph then its all 55mph for another 20 min, about half way there it started stumbling , i have to keep backing off the throttle to keep moving or it keeps backfiring. also if i turn it off for about ten min it starts and runs ok again for a little while.
|
|
|
Re: xj studdering problem
[Re: fulltime79]
#871073
02/24/08 07:53 PM
|
Joined: Oct 2003
Posts: 7,768
Web Wheeler
|
sorry guys, heres the deal. started about three weeks ago, doesnt matter weather im driving or not. happens while ideling in the driveway, or while driving down the road at any speed. motor starts stumbling and backfiring through the intake. yesterday i replaced the pump/regulator/filter assy. started it up, let it run in the drive, about ten minuits or so it started stumbling. Ok backfiring up front is either a burnt intake valve or intermittent firing.. So we look at the coil and the dist trigger first and then do a compression check of the cylinders.. Are the plugs properly gapped? Well worn plugs might cause the coil to overload and possibly cause intermittent firing. I seriously doubt a fuel problem. Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />
professional bovine relocation specialist
|
|
|
Re: xj studdering problem
[Re: BigJim]
#871074
02/25/08 03:12 PM
|
Joined: Feb 2008
Posts: 17
OP
Need a Spot
|
ok, I"ll try plugs,cap and rotor, and new plug wires and test the coil to see if that works and drop you a line to let you know the outcome. tune in tomorro to find uot what i find <img src="/forums/images/graemlins/smile.gif" alt="" />
|
|
|
Re: xj studdering problem
[Re: fulltime79]
#871075
02/25/08 03:19 PM
|
Joined: Feb 2008
Posts: 17
OP
Need a Spot
|
I dont think its a valve problem, problem is just too unpredictable. some days the damn thing will run fine no one of my 30 -40 mile jaunts, other times as soon as i start it up to idle. just gets under your skin you know. <img src="/forums/images/graemlins/rolleyes.gif" alt="" />
|
|
 Re: xj studdering problem
[Re: fulltime79]
#871076
02/25/08 04:22 PM
|
Joined: Oct 2003
Posts: 7,768
Web Wheeler
|
I'm betting on wires being twelve hundred years old causing the problem in moist weather.. Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />
professional bovine relocation specialist
|
|
|
Re: xj studdering problem
[Re: BigJim]
#871077
02/26/08 07:19 PM
|
Joined: Feb 2008
Posts: 17
OP
Need a Spot
|
Well, no luck getting any work done today. Snow means I have plowing to do. I hate when that happens, try again tomorro , thats the problem with working graveyard shift. Guess Ill just have a <img src="/forums/images/graemlins/cheers.gif" alt="" /> and get some <img src="/forums/images/graemlins/sleeping.gif" alt="" /> and get back with you tomorro, till then <img src="/forums/images/graemlins/patriot.gif" alt="" />
|
|
|
|
