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Old 06-06-2008, 02:38 PM   #1
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Couple engine questions

Hello all… New to the board.

I just recently purchased a 1987 Jeep Wrangler. Been doing some work and am now trying to get the engine dialed in.

It has the 6cyl. 258.

Couple issues I’m dealing with.

1st. The engine has a hesitation at about 2800-2900 RPM. Picks back up but is lazy after that. Seems like the engine leans out and does not fully recover.

2nd. The engine has an intermittent rough idle. If I stop a stop light it will drop RPM and rumble… only about 25% of the time though… the rest of the time she just idles great.

The engine only has about 70k miles on it and used to run great. I’ve been around the Jeep since it was bought new in 1987. My father-in-law bought it and used it for hunting. When he bought a new Rubicon this year I bought it since I like driving it so much… so I know she used to have a lot of zip… just a little lazy now.

Any help or advice would be great.

Thanks,
JC

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Old 06-06-2008, 06:18 PM   #2
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Not positive on the first problem, but the 2nd problem sounds like the carb has a saturated float. A rebuild kit will cost about $40, or you could buy a new re-manufactured one, or upgrade. An upgrade to a Weber or Holley would be the best choice.

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Old 06-06-2008, 08:04 PM   #3
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Yeah, I was thinking about putting a new carburetor on it. Looking at the Weber in a Jeep Catalog. Since I was putting $$ in to some other things on my list like Wheels, Tires, bumpers, Carpet kit, and all new top… I was hoping to avoid any other bigger ticket items. They all seem to run about $500. But if that’s what it comes down to I’ll have to bite the bullet.

I have a buddy that used to work on Jeeps at a dealership and he came by and we lifted the metering rods in the current Carter Lean Burn carb. Put a new O2 sensor on it and did a complete tune up with Cap, Rotor, Plugs and Wires. Also have a new Coil. Lifting the metering rods helped the motor come alive a little but did not eliminate the 2800 RPM Hesitation. The best way to describe it is… I used to race cars and you can feel the motor was giving up it wanted to lay over on the top end. My buddy told me these lean burn systems are pretty frustrating to work on when something is not working right.
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Old 06-07-2008, 03:00 AM   #4
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I have ZERO experience with "lean burn" systems. Quite infact, I've never heard of them. I'm sure a handful of board members know what you're talkng about.

As far as Webers go, a replacement for your application will run about $410.

I'd also like to suggest the EMPI Performance Carb. One for your application will run about $300. It's part number 51318.100 in Quadratec. It should give you about 15% better gas mileage then the Carter 2bbl, and15-20% more ponies.
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