87-90 2.5L Throttle Body Rebuild Process - JeepForum.com
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Unread 11-25-2011, 12:35 PM   #1
schaef89
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1989 YJ Wrangler 
 
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87-90 2.5L Throttle Body Rebuild Process

I recently rebuilt the Throttle Body on my 89 Wrangler's 2.5L and decided to share the process with the forum. I know I was curious of the process prior to starting the rebuild, but saw no pictures or write ups of it. So here's my experience doing the rebuild..

I started by buying a Rebuild Kit


Then I started the tear down, what it should look like at the beginning


Removed the Air tube


Once the Air tube was off it was easier to get to the other components. Removed the IAC bracket and throttle cable. Three torx screws hold on the bracket, and there are two harness plugs to unplug to get it off the motor. Also removed the top throttle body mount for the air tube that are held on by three plastic nuts.


Once all that was off, I separated the vacuum hardlines from the manifold and the throttle body. I also unplugged the rest of the harness and moved it to the side. I believe at this point I also disconnected the fuel lines in the rear of the throttle body.


At this point, it's a good idea to check the four short vacuum hoses that connect the hardlines to the throttle body. I found this on mine, which led me to replacing all four


Throttle body removed. It's held on by four 1/2 nuts, which are in awkward positions to get a wrench in. However, it only took a bit of patience to remove them. Also stuck a paper towel so no debris fell in


Now this is the fun part, ripping into the throttle body itself. I place it in a box so i didn't lose any necessary screws or parts.


Remove the fuel injector retaining ring, held in by two torx screws.


The FSM says to pry out the injector using a screwdriver. The one pictured is actually new as I had to replace a leaky injector prior to the rebuild.


Popped out. Note the O-ring positioning while it comes out. The smaller one is at the bottom and the bigger one seats around the middle of the injector.


Once the injector was removed, the TPS sensor need to be removed. This was also replaced by me prior to this rebuild


Next is the fuel regulator housing. Three torx screws to remove it


Removed. There is a cup and spring within that housing, as well as the regulator itself


Next was splitting the halves of the throttle body. Three torx screws


Removed and split apart.


At this point I soaked all the throttle body components in carb cleaner for about an hour each. I was not too concerned about the outside dirt at this time but I wanted the inside carbon and fuel residue removed. This is basically the reverse of the tear down but I wanted to show the full process.

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Unread 11-25-2011, 12:35 PM   #2
schaef89
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I started putting it back together by putting the regulator in first. When I took it out is was hard to get my torx socket on one of the screws. Make sure the spring is seated on the regulator during installation.


Tightened down. I tightened each screw a little at a time to have the spring bear down evenly.


Next was the mating the two halves again. I cleaned both surfaces by removing the old gasket (stuck on there pretty good) and wiping with a rag to remove any grease


Mated and tightened down


Then I reinstalled the TPS sensor


As well as the Injector, Injector O-rings, and retaining ring


At this point you have a freshly rebuilt TBI throttle body


Install your engine components in the reverse of removal and you're good to go.


This rebuild was a lot simpler than I originally thought, based on the amount of gaskets that came in the kit. It only required 3 gaskets, 2 O-Rings, and a fuel regulator for the complete build. The entire process took me about 2 hours, without adding the time the parts soaked in carb cleaner.

I hope this information helps someone in the future. As simple as it turned out, at the beginning I was even wary of how much time/skill would be involved in doing this rebuild. Feel free to ask any questions you may have as I've probably overlooked some documentation during the process.

Happy Jeepin'
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Unread 11-25-2011, 02:46 PM   #3
oldtime_ironman
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EXCELLENT write-up, complete with pics! I don't think anyone's done a write-up on the TBI rebuild before, that I know of. So a bunch of people could really use this info. Your old fuel pressure regulator definitely needed it - I'm amazed it even had rust on it and still ran. It must have had real bad gas or sat forever. BTW could you post the brand name and part number from the rebuild kit you used?
.
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Unread 11-25-2011, 02:57 PM   #4
schaef89
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Thanks.. The rebuild kit was Standard Motor Products #1605 and the fuel injector was BWD #57090
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Unread 12-13-2011, 11:36 AM   #5
Que89YJ
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I posted this link in another thread. Awesome job! I plan on using your thred to do mine in the near future did you notice a difference when you were done? Did you have to redo the Idle motor and TPS adjustments when you were done?
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Unread 12-13-2011, 11:59 AM   #6
schaef89
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Quote:
Originally Posted by Que89YJ View Post
I posted this link in another thread. Awesome job! I plan on using your thred to do mine in the near future did you notice a difference when you were done? Did you have to redo the Idle motor and TPS adjustments when you were done?
Thanks Que.. I did notice a little smoother idle, but that may have been caused by the new injector since the old one was leaking. I didn't do the adjustments yet, but plan to do those in the very near future
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Unread 12-13-2011, 12:35 PM   #7
Que89YJ
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What symptoms did you have with the bad injector? How did you find it? Did you find it in the fuel pressure bleed down test?
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Unread 12-13-2011, 12:47 PM   #8
schaef89
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The symptom that led me to the bad injector (among many issues) was a hard start after it was warmed up. It happened a lot on highway runs. Where I would stop to fill up the tank, go to start it, and I'd have to cycle the gas pedal to make it start. I could also see A LOT of fuel splashing around on top of the butterfly valve during idle when I looked more into fixing it, as well as carbon blowing out of the exhaust when it was cold
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Unread 02-01-2012, 12:53 PM   #9
Que89YJ
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This is the test port. Edit: Wrong PIC!
The second one shows the test port:
speedo-sensor-pic.jpg   100_1869.jpg  
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Unread 02-01-2012, 01:09 PM   #10
Que89YJ
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You can see the port in the upper left hand of the TBI top in the pic directly across from the pressure regulator. I thought it was a torques but I am not sure.
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Unread 02-01-2012, 01:21 PM   #11
schaef89
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I've found that already, I just need to get a fitting that goes in that to the schrader valve on the test gauge. I bought one off amazon. It's an 1/8 NPT to Schrader valve adapter (tank valve). We'll see if that works
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Unread 02-03-2012, 12:42 PM   #12
Que89YJ
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Thread it and tap it with a nozzel and a short piece of hose. You can get everything you need to do it at any of the parts store.
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Unread 02-03-2012, 12:56 PM   #13
bharris68
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Awesome thread - thanks for the pictures and very clear write up - thumbs up, rated Excellent!
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Unread 09-23-2013, 08:02 AM   #14
JeepArt
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None of the rebuild or o-ring kits I find include the centering ring for the fuel injector. Is that a critical for the placement of the injector?

Also, could you describe for me the order and placement of the two o-rings on the injector? I believe the small one slides over the injector nozzle up to the fuel screen, but where does the second one go?

I'm trying to resolve a bad installation by the PO.

TIA!
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Unread 09-23-2013, 10:37 AM   #15
schaef89
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Quote:
Originally Posted by JeepArt View Post
None of the rebuild or o-ring kits I find include the centering ring for the fuel injector. Is that a critical for the placement of the injector?

Also, could you describe for me the order and placement of the two o-rings on the injector? I believe the small one slides over the injector nozzle up to the fuel screen, but where does the second one go?

I'm trying to resolve a bad installation by the PO.

TIA!
Jeepart,

I posted up in your thread, but will respond here as well.

I would assume it is critical based on the fact that it was there from the factory. It will also help create a uniform "squeeze" on the upper o-ring.

The placement goes from top to bottom: Plastic Ring around upper injector OD, upper o-ring at the point the injector OD increases, then lower rubber o-ring around injector nozzle at the bottom.

These diagrams from the FSM should help. The plastic piece is there but not listed
tb.jpg

capture1.jpg

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