Help failed smog
Thread Starter
Member
Joined: Jan 2011
Posts: 203
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From: Petaluma CA
Year: 1989
Model: Cherokee
Engine: 4.0
So Im on the fence about things that could be wrong with my jeep. I had one mechanic tell me that all I needed was a new CAT and then I went to a muffler shop and he looked at the emissions sheet and saw the numbers and said I have engine issue and it's getting to much gas any help please?
Thread Starter
Member
Joined: Jan 2011
Posts: 203
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From: Petaluma CA
Year: 1989
Model: Cherokee
Engine: 4.0
Originally Posted by Slick761
I'll show you what smog shop to take it to lol.
Senior Member
Joined: Aug 2011
Posts: 760
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From: Landers, CA
Year: Several
Model: Cherokee
Engine: 4.0
She's too rich - too much fuel - hi CO - check the vacuum line to the fuel pressure regulator - main reason for these to be too rich. Get CO down the rest will drop with it.
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CF Veteran
Joined: Jun 2011
Posts: 2,858
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From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Originally Posted by eeppower58
Next to ihop right? But the guy at the smog place to test it again it would only be 20 bucks
I had a similar test last weekend. Cleaned air filter, 1 can of Seafoam($8) in 1/2 tank of gas, new plugs ($12) and a o2 sensor ($52).. the 91 passed with flying colors.
Don't know which did the trick as I tried them all at once. LOL.. I suspect the o2 as have been original equipment though. Looked very unfunctional.
Don't know which did the trick as I tried them all at once. LOL.. I suspect the o2 as have been original equipment though. Looked very unfunctional.
also before you take it in next drive the hell out of it get the cat nice and hot to allow it to do its job, let it sit and idle while you wait your turn, believe it or not it helps alot, also if you haven't done it recently change your oil, also makes a difference.
CF Veteran
Joined: Jun 2011
Posts: 2,858
Likes: 1
From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Eepower check out san Francisco bay area monthly meet thread in the pacific northwest section of the forum. Were trying to get bay area cherokees to meet up.
Thread Starter
Member
Joined: Jan 2011
Posts: 203
Likes: 0
From: Petaluma CA
Year: 1989
Model: Cherokee
Engine: 4.0
Originally Posted by Slick761
Eepower check out san Francisco bay area monthly meet thread in the pacific northwest section of the forum. Were trying to get bay area cherokees to meet up.
Senior Member
Joined: Aug 2011
Posts: 760
Likes: 6
From: Landers, CA
Year: Several
Model: Cherokee
Engine: 4.0
Theoretically a higher voltage to the pump would make it spin faster - more pressure. BUT the pressure regulator would cut it back down.
All it really would do is shorten the life of the pump.
The pressure regular uses manifold vacuum, it's job is to maintain fuel pressure in the rail a set pressure above manifold vacuum.
the proper test -- compare fuel pressure in the rail compared to manifold vacuum. It should remain constant no matter what the speed or load.
If the hose leaks, or the regulator is defective, it will give too much fuel pressure - HI CO!
All it really would do is shorten the life of the pump.
The pressure regular uses manifold vacuum, it's job is to maintain fuel pressure in the rail a set pressure above manifold vacuum.
the proper test -- compare fuel pressure in the rail compared to manifold vacuum. It should remain constant no matter what the speed or load.
If the hose leaks, or the regulator is defective, it will give too much fuel pressure - HI CO!


