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post #1 of (permalink) Old 03-06-2001, 01:38 AM
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stumbling 4.3

I just bought a 92'jimmy about a month ago, and i'm getting frustraded with it already.It seems to idle roughly, and continues to stumble until the rpm's pick up.I replaced the plugs,wires,cap,rotor,airfilter,fuelfilter,and it ran great for 20miles.Still the same!Iv'e checked all the vaccum lines,to no avail.What could it be? Thanx alot!!!

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post #2 of (permalink) Old 03-06-2001, 07:01 AM
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Re: stumbling 4.3

check the timing.

post #3 of (permalink) Old 03-06-2001, 11:53 PM
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Re: stumbling 4.3

I checked the timing,and it was good.She's got 98,000 miles on her,and I'm really hoping it doesn't have an internal engine problem.any more thoughts? thanks

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post #4 of (permalink) Old 03-07-2001, 12:17 AM
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Re: stumbling 4.3

id try running some fuel injector cleaner (it is fuel injected correct?) thru the gas tank

Richard

85 S-10 3.4L cat-back exhaust otherwise stock for now
post #5 of (permalink) Old 03-07-2001, 12:27 AM
 
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Re: stumbling 4.3

<font face="Comic Sans MS">When was the last time the O2 sensor was changed? I'm not sure if that's the problem but if a sensor is bad (even if it's not bad enough yet to trip the check engine light) it can play hell with the way the engine runs. Might want to have a shop scan the truck for trouble codes just in case. If they have one of the better code scanners they can easily check the inputs (I believe) from the sensors to see if there's one that's messing things up by being out of spec...

Does it seem to be running rich or any such thing? Pull the spark plugs and look at them. They should be a tan color. If they've got carbon on them then for some reason it's running rich.

Actually take some water, WD40, or other such item and spray it around all of your seals and things. You could have a vacuum leak. That would exhibit similar symptoms. If you spray those type of items at the place the leak is you'll notice a change in how it's running. Then after that all that'd be left would be to change the offending gasket(s)... [img]/wwwthreads_images/icons/crazy.gif[/img] At least a few more items to check.. I'd check it yourself for vacuum leaks before taking it in to get scanned... [img]/wwwthreads_images/icons/crazy.gif[/img]</font>

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post #6 of (permalink) Old 03-07-2001, 02:58 AM
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Re: stumbling 4.3

Thanks for the advice!Its going to the shop tomorrow to get looked at.I checked for vaccum leaks like you recommended,but it was hard for me to tell(we just got pounded with a snowstorm in upstate ny,and its tough working on it in 3 ft of snow). Wish me luck,and thanks for the help!!!

post #7 of (permalink) Old 03-07-2001, 03:04 AM
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Re: stumbling 4.3

I ran some prestone fuel injector cleaner/gas line antifreeze through the tank about 2 tanks ago,and it didn't seem to run any better.(it is fuel injected) thanks!

post #8 of (permalink) Old 03-07-2001, 03:09 AM
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Re: stumbling 4.3

Could be a coolant temp sensor, TPS or a MAP sensor ( do 4.3's have them?


And check the trouble codes.......

post #9 of (permalink) Old 03-07-2001, 10:03 PM
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Re: stumbling 4.3

I just did a tune-up for a friend of mine on his '92 Jimmy 4.3L. 5" suspension lift 3" body, 33" mudders. I did evertything you did and it still felt sluggish, turns out the catalitic converter was clogged. Just another idea.

-Ryan Primel
Suzuki, Jeep, Chevy, Ford, who cares, as long as you're out on the trails wheelin'.
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post #10 of (permalink) Old 03-07-2001, 11:30 PM
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Re: stumbling 4.3

This may sound stupid but, check your fuelfilter again... i just resurected a 85 ply. horizon exibiting the same problems, i changed the fuel filter, it ran fine for about 20 min. i changed everything else and it didn't help. So i checked the fuel filter again and it was clogged, with rust, the car sat with no gas in the tank(or running it past empty) it sucked up all thoes little rust particles in the tank, unless you have a plastic tank you could have this prob.. Just a thought!

Tim


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