Sluggish YJ Suggestions? Common Problem? - Page 2 -
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Unread 04-13-2010, 08:44 PM   #16
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1993 YJ Wrangler 
Join Date: Dec 2009
Location: Purcell, OK
Posts: 21
Check fuel pressure at the rail, the in tank gas pump has a fuel hose that can deteriorate over time and allow the fuel to seep within the tank and the fuel pressure to drop and cause sluggish throttle. The addition of ethinol has made this problem more prevelent over the last few years depending on your region of the country.

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Unread 04-13-2010, 08:54 PM   #17
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1994 YJ Wrangler 
Join Date: Aug 2009
Location: Lexington,SC
Posts: 1,836
My 4.0 is pretty much a slow dog...I have 32 tires, not sure gear ratio. Manual tranny. Runs fine, just not a speed demon. I figure that's just how it is.
1994 YJ Wrangler, 4.0, AX15, NP231, 35x12.50x15 BFG KM2s, 4" RC lift, 1" lift Boom Shackles, 1" BL, 4.10 gears, 8.8 LSD in rear and D30 Aussie Locker in front, on-board air conversion, Ramsey RE8000 winch.
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Unread 04-13-2010, 09:00 PM   #18
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1989 YJ Wrangler 
Join Date: Apr 2010
Location: south jersey
Posts: 14
i have the same problem its just the nature of the beast mine is a 5 speed and 89 and its a turn compared to my buick with a 3.8
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Unread 04-13-2010, 09:44 PM   #19
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1995 YJ Wrangler 
Join Date: Feb 2009
Location: Los Angeles. California. United States.
Posts: 4,910
I bought a fuel pressure tester at Harbor Freight for 10 bucks. May not be a bad idea as mentioned. ^ I run a very high 50% blend of clean alcohol fuel. I have checked my lines and been using it for several years at this blend. I don't think it is an issue with 90's on newer vehicles, my lines are in great condition. It was manufactured knowing that alcohol was going to be part of the fuel, they started doing that in the late 70's, and improved greatly into the 90's with compatibilty from there. 90's on newer vehicles I believe this is a non-issue It may still be a problem, dunno. My jeep loves the stuff and have seen no ill effects from my own experience using it. But again, maybe some are seeing problems.
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Unread 04-13-2010, 10:09 PM   #20
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1994 YJ Wrangler 
Join Date: Feb 2009
Location: Charlotte
Posts: 150
well, now that its understood that it is not a trans issue. i would go to harbor freight (super cheap tools!) and get the fuel pressure gauge/tester, and check there. my fuel pressure was really low, so i replaced my fuel pump (in the gas tank, so had to drop the tank) and power went back up. also check for vacuum leaks. it sounds kind of silly, but they really do make a difference in power. (maybe not the whole reason, but added to something else?) they control all kinds of things like the fuel rail pressure regulator. these vacuum leaks are extremely common on the yj's.
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Unread 04-14-2010, 12:29 PM   #21
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2004 TJ Wrangler 
Join Date: Nov 2008
Location: New Jersey
Posts: 27
I work on this particular jeep all the time, and see it daily (live around the corner). The engine is running strong, smooth (enough for a yj) and loud with the borla. I don't think that the issue is fuel pressure. the rpms are there, the power isn't.... I'm leaning more towards the trans/torque converter. However all my trucks have been manual so i cant really offer up much advice to the auto problems...
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Unread 04-17-2010, 04:53 PM   #22
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1995 YJ Wrangler 
Join Date: Jun 2008
Location: New Jersey
Posts: 200
Thanks for the first hand mention of my Jeep Andrew, it is easier when you've actually seen it and describe it too (I don't think I did the best job).

I'm thinking maybe I'll get some of that injector cleaner just to rule that out and see if it improves, since I think a few people mentioned that as a problem. If that isn't the problem I'm sure my injectors need some cleaning in general.

I guess as many also agree that it is the torque converter, I feel that is a large project just to replace that myself. Hoping for a nice weekend to take everything apart.
1995 Green Jeep Wrangler
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