running rich?

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Aug 5, 2010 | 12:58 PM

grimmace

Thread Starter

Newbie

Joined: Aug 2010

Posts: 2

Likes: 0

From: vestal new york

Year: 2000

Model: Cherokee

Engine: 4.0

running rich?

i just bought a 2000 cherokee with 4.0. it seems to be running rich, and if left sitting for a few days i get a puff of smoke at start up. any ideas? im thinking valve seals. if changing them a big problem?

Aug 5, 2010 | 05:19 PM

ca441970

Member

Joined: Jun 2010

Posts: 155

Likes: 1

From: Easthampton, MA

Year: 1999

Model: Cherokee

Engine: 4.0

Smoke color?

Black- unburned fuel
Blue-oil
White- antifreeze or just water burn off from fuel

Running rich would be black smoke and O2 sensors were making mine run rich.

Aug 5, 2010 | 05:22 PM

truckntractorhick

CF Veteran

Joined: Dec 2009

Posts: 2,091

Likes: 1

From: Harleysville, PA

Year: 1998

Model: Cherokee

Engine: 4.0L I6 Powertech

CEL?

Aug 6, 2010 | 09:34 AM

grimmace

Thread Starter

Newbie

Joined: Aug 2010

Posts: 2

Likes: 0

From: vestal new york

Year: 2000

Model: Cherokee

Engine: 4.0

what is cel like i said im knew to jeeps

Aug 6, 2010 | 11:46 AM

notop46

Seasoned Member

Joined: Jun 2010

Posts: 448

Likes: 0

From: Charleston, SC

Year: 1990 - 2000

Model: Cherokee

Engine: 4.0

O2 sensor of air filter

Check Engine Light

Rich = black smoke, dark spark plugs, and poor gas mileage
Reason: O2 sensor bad, dirty air filter....

Puff of white smoke after sitting a few days is most likely valve seals. There is a bit of work involved. It can be done with the engine in the car and the head on.