'90 YJ sputtering at speed - JeepForum.com
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post #1 of 5 Old 06-20-2011, 10:07 PM Thread Starter
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1990 YJ Wrangler 
Join Date: Jun 2011
Posts: 2
'90 YJ sputtering at speed

Ok, this is my first post... be gentle

I just bought a 1990 YJ 6 cylinder 4.2L. It hadn't been running for a while when I bought it... the PO said it was a month, but who knows? I just replaced the belts, cleaned the carburetor, seafoamed the engine and the gas tank, changed the oil and put on a new oil filter (in terms of anything that would have an effect upon the engine).

Driving tonight at speed (65 mph) in fifth gear, engine sounds like it's sputtering. I gave it some gas and the engine sputtered some more. No speed increase or increase in RPMs. I dropped it into fourth, same issue.

Then I took it onto the shoulder and let it coast, dropped it into third and gave her some gas, and the engine sounded normal--no sputtering--, the speed picked up (as did the RPMs) when I gave it some gas. I shifted up into fourth, got back on the road and everything was good. Up into fifth again... no problems for the rest of the drive. Fuel filter? At first I thought it was the clutch since the RPMs weren't going anywhere and it felt the same way as my old car did when the clutch died. But there wasn't any sputtering when that happened. Any ideas?

Last edited by fchaleff; 06-21-2011 at 11:07 PM. Reason: Back on a computer rather than a phone... easier to be more clear.
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post #2 of 5 Old 06-20-2011, 10:08 PM Thread Starter
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1990 YJ Wrangler 
Join Date: Jun 2011
Posts: 2

Last edited by fchaleff; 06-21-2011 at 11:08 PM. Reason: I took out redundant info.
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post #3 of 5 Old 12-18-2012, 05:30 PM
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1990 YJ Wrangler 
Join Date: Jan 2012
Location: poco
Posts: 13
Any help
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post #4 of 5 Old 12-19-2012, 11:51 PM
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1989 YJ Wrangler 
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Location: Sin City
Posts: 2,881
Plenty of things to conssider. The easy cheap stuff fuel filter, does it need a good tuneup look inside the cap at the contacts for each cylinder pull the plugs read the story of how it iis burning (pics attached), maybe the sputtering is from not running and you stirred up some debris in the tank and it clooged the filter sock in the tank.

Feul filter
Tune up (Rotor,cap wires, plugs)
Attached Thumbnails
Spark Plug Reading.jpg  

89YJ 2.5L TBI, AX-5, NP231 SYE, Ford 8.8, Yukon Grizzly, Tom Woods Shaft, 33" BFG T/As, 4" lift, Warn VR10000s.

AF Jeep Club Tail #184
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post #5 of 5 Old 12-24-2012, 11:39 AM
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1990 YJ Wrangler 
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Location: Jacksonville
Posts: 749
Joker is prolly right here. Clogged filter will not feed enough fuel at high speed and a bad cap, wires or dirty plugs will do the same. Look for carbon tracing in and outside of the cap. Open the hood at night and see if there is a light show when you rev up the engine. ICM may also be at fault but check everything else first, its a $60 part.
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