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  #1  
Old January 18th, 2022, 09:56
racintck racintck is offline
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89 Vacuum System

Hey Guys! Noob here.

I recently bought an 89 XJ to use offroad only and being that old and all the brittle plastic vacuum parts under the hood, I wanted to eliminate as much of that stuff as possible. This is my first introduction to Jeep as I was mainly GM based powerplants. Is there a specific write up that can point me to what can be removed without messing up the computer since this thing is FI?


Thanks in advance.
TC
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  #2  
Old January 18th, 2022, 11:02
Black_Black Black_Black is offline
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Re: 89 Vacuum System

You can get new vacuum lines for not much money. It comes in a left and right side and clips together. Not much to be gained messing with oem
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  #3  
Old January 18th, 2022, 11:17
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old_man old_man is offline
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Re: 89 Vacuum System

The system is set up to use the engine vacuum to measure what is going on in the system and tell the computer how to compensate. Removing them will totally screw up your performance.
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  #4  
Old January 18th, 2022, 12:37
racintck racintck is offline
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Re: 89 Vacuum System

Thank you for the quick response. (forgot to put in that it is a 4.0l auto 4wd)

You know how it goes "I was hoping for a different response, but I will take it." I ordered the left and right vacuum harness.

Normal vacuum at idle around 15inches?

Right now it has a super high idle which I was attributing it to all of the vacuum leaks. Hopefully I am headed in the right direction.
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  #5  
Old January 18th, 2022, 13:47
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Saudade Saudade is offline
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Re: 89 Vacuum System

Also check the vac line from the throttle body to the map sensor on the firewall. It's not part of the harness.

Vacuum lines also operate the EGR valve, the HVAC vents, the hot air valve (front of the air cleaner) and the cruise control (if you have it). These are also not part of the harness so check them all.
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  #6  
Old January 19th, 2022, 04:13
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cruiser54 cruiser54 is offline
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Re: 89 Vacuum System

I wish I could post photos here.......

Anyway, make sure you go to www.cruiser54.com and complete Tips 1 through 5.
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  #7  
Old January 26th, 2022, 12:11
racintck racintck is offline
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Re: 89 Vacuum System

Quote:
Originally Posted by cruiser54 View Post
I wish I could post photos here.......

Anyway, make sure you go to www.cruiser54.com and complete Tips 1 through 5.
I have his page bookmarked now, thank you.

This weekend I pulled all the vacuum lines and replaced both vacuum harness halves from Rockauto, cleaned out the IAC and at the moment the only vacuum lines that are active are associated to the motor. It does idle about 1k while in park right now, but I am currently battling a previous hack job on the electrical wiring. When I did have it running, I noticed an exhaust manifold like at the head and I could only image the intake leaks as well.

Owning older vehicles are not for those without patience.
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  #8  
Old January 26th, 2022, 15:45
Black_Black Black_Black is offline
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Re: 89 Vacuum System

My 89' had a high idle as well, a new TPS fixed it. Adjustment instructions are on Cruiser's website
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  #9  
Old January 26th, 2022, 16:47
racintck racintck is offline
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Re: 89 Vacuum System

Thanks for the suggestion Black_Black. I got it back running and then it started dogging out when trying to accelerate so, I brought it back home and shut it off. When I started it back up it shuttered and stumbled so bad until it died on me.

And that is where I am at now. Turns over but doesn't start.
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  #10  
Old January 26th, 2022, 22:28
Black_Black Black_Black is offline
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Re: 89 Vacuum System

How is your fuel pressure? Check out the ballast resistor
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  #11  
Old January 27th, 2022, 03:54
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Re: 89 Vacuum System

Check the integrity of the Hose/tube from the throttle body to MAP sensor.
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  #12  
Old January 27th, 2022, 05:00
racintck racintck is offline
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Re: 89 Vacuum System

I will check both of those tonight and see what is what. I don't think the fuel gauge works which is on the list to resolve as well. Good thing you don't have to drop the take to do that task.

Quote:
Originally Posted by Black_Black View Post
How is your fuel pressure? Check out the ballast resistor
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  #13  
Old January 27th, 2022, 05:02
racintck racintck is offline
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Re: 89 Vacuum System

I did give a quick look over and I am planning on doing the upgrade as suggested. Like every vacuum line on this thing, it is probably shot and I am sure if I touch it, it will disintegrate.

Quote:
Originally Posted by cruiser54 View Post
Check the integrity of the Hose/tube from the throttle body to MAP sensor.
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  #14  
Old January 27th, 2022, 16:18
racintck racintck is offline
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Re: 89 Vacuum System

Replaced the plugs, cap and rotor tonight and currently has a random stumble and hesitation when throttling up.

Map sensor hose and connectors seem to be okay as I fumbled around them and no change.

Fuel pump ballast are in working order.

Good thing is now the idle is about 800rpm.
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  #15  
Old January 28th, 2022, 03:56
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Re: 89 Vacuum System

How old are the plug wires?
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