88 4.0 running SUPER duper rich
Thread Starter
Senior Member
Joined: Mar 2013
Posts: 546
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From: Chehalis, WA
Year: 1988
Model: Cherokee
Engine: 4.0L
Title says it all, my 88 is running extremely rich and likes to die and burp a lot now... If I get on it, it blows straight black out the pipe. I'm getting HORRIBLE gas mileage, and really down on power. It's been doing it since I sank it at Tahuya (damn it). Any ideas?
I have replaced, fuel pump, plugs, wires, rotor.
I have replaced, fuel pump, plugs, wires, rotor.
Senior Member
Joined: Nov 2008
Posts: 510
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From: Oak Harbor, Wa
Year: 1987
Model: Cherokee
Engine: 4.0 Renix
Title says it all, my 88 is running extremely rich and likes to die and burp a lot now... If I get on it, it blows straight black out the pipe. I'm getting HORRIBLE gas mileage, and really down on power. It's been doing it since I sank it at Tahuya (damn it). Any ideas?
I have replaced, fuel pump, plugs, wires, rotor.
I have replaced, fuel pump, plugs, wires, rotor.
CF Veteran
Joined: Nov 2008
Posts: 6,989
Likes: 4
From: Oak Harbor, WA.
Year: 1987
Model: Cherokee
Engine: 4.0 liter RENIX I-6, DIY Cold Air Intake, 2.5 FM Exhaust, 3 Core Radiator
Which sensor did you try? The guys said to test your O2 sensor and your MAP sensor.
Is it running rich at idle, while giving it throttle or both?
Have you checked for vacuum leaks? Introducing extra intake air other than where its supposed to be will cause the computer to over richen the mixture.
Have checked all the basic things like a clean air intake filter and an un-obstructed air intake?
How about the Fuel Pressure Regulator? have you checked fuel pressure at the fuel rail. If its waaaay too high the regulator could be stuck or the vacuum line to it could have fallen off or be leaking.
Is it running rich at idle, while giving it throttle or both?
Have you checked for vacuum leaks? Introducing extra intake air other than where its supposed to be will cause the computer to over richen the mixture.
Have checked all the basic things like a clean air intake filter and an un-obstructed air intake?
How about the Fuel Pressure Regulator? have you checked fuel pressure at the fuel rail. If its waaaay too high the regulator could be stuck or the vacuum line to it could have fallen off or be leaking.
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CF Veteran
Joined: May 2009
Posts: 1,844
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From: Glen Burnie, MD
Year: 1994
Model: Cherokee
Engine: 4.0 H.O. K&N, Borla headers, custom down pipe, magnaflow hi-flo cat, flowmaster to turn down tip
when you say you sunk it, did you get water in the engine when you "sunk it"?
Thread Starter
Senior Member
Joined: Mar 2013
Posts: 546
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From: Chehalis, WA
Year: 1988
Model: Cherokee
Engine: 4.0L
It went under water at tahuya, I'm sure there's some pics on this thread, or in the April tahuya thread. And no no water in the engine, we pulled the plugs, and turned it over, no water came out.
Thread Starter
Senior Member
Joined: Mar 2013
Posts: 546
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From: Chehalis, WA
Year: 1988
Model: Cherokee
Engine: 4.0L
Thread Starter
Senior Member
Joined: Mar 2013
Posts: 546
Likes: 0
From: Chehalis, WA
Year: 1988
Model: Cherokee
Engine: 4.0L



any other ideas?
she lives again!!