Rebuilding a tbi and things in pieces - First Generation Forum

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Rebuilding a tbi and things in pieces
Friday, April 19, 2013 8:56 PM
Ok first pic is of untouched tbi and dirty as crap.I took this all apart even the butterfly and arm that does the throttle.I took the fuel press regulator apart needs new gasket.I pretty much degreased and used my cordless black/deck with a fine brush 1/4 inch shank from lowes to luster the aluminum up and clean out the ports and and it is all clean.I will buy a gasket kit maybe next wk and reassemble it but,for those who have not tackled it and seen this ALL apart here it is.Took me a about a hour and half to get it set for new gaskets which were toast.I may venture to make a video and while this may take some time I would like to show a short of how to do this.

Re: Rebuilding a tbi and things in pieces
Saturday, April 20, 2013 6:20 AM

That is CLEAN. You should go into the carb/tbi rebuilding business! Nice work Ron!
A video or a how-to post on here with part numbers for the kits would be great.

Re: Rebuilding a tbi and things in pieces
Saturday, April 20, 2013 8:37 AM
Wow beautiful work Ron! What lb/hr is the injector?

"In Oldskool we trust"
Re: Rebuilding a tbi and things in pieces
Saturday, April 20, 2013 8:17 PM
Ron I do believe you can make a silk purse outta a Sows Ear!!

Seriously you sure are great at polishing and shining it up!! I believe in the end you are going to make the Throttle Body and easy overhaul for all of us. We can be be mighty grateful to you for that!! So ironic that in the 1st Gen heyday this stuff was cutting edge and something only the brave dare tread. Now these machines represent some of the last examples of easy to work on - do it yourself Autos.

Keep up the great work and Thanks for the Insight!!


Re: Rebuilding a tbi and things in pieces
Saturday, April 20, 2013 10:37 PM
yellowcav it still has the stock size injector that runs 9-13psi.This model is more than likely the 500 and pretty much like mine but,maybe subtle changes mostly with the injector.Orlen thanks for the encouraging words.Being I have done my own and this was a junkyard buy I wanted to take it all apart and get it set for a instructional idea I have had for well almost two years.I do have to buy a rebuild kit and will skip buying a new injector at this time.I did a quick check and auto zone sells a kit with all the gaskets and orings But not the fuel pressure regulator side(idk why) bc my old kit for sunny came with ALL of it.I hope I can dig more into the parts choices and do believe I bought my original kit from advance and was under 40.00 with everything.Once I do some homework I can narrow down a few things and make it simple.Worked today so no extra digging on this for tonight.I do plan a video and try to get it set with all the parts for a say 10-15 time and I will get it all figured out once I buy the kits or kit to fix the spare.

Re: Rebuilding a tbi and things in pieces
Sunday, April 21, 2013 6:00 PM
Hi Ron,

A while back my good JBody friend Tom Stoup, did a LOT engine work on my 84 Cavalier. It had a bad exhaust manifold so he had an extra from an 85, so he did a major project of swapping out both exhaust and intake manifolds. At the same time, he also had an TBI from his 85, that also had to be swapped out. I bought the rebuild kit from Auto Zone, and he rebuilt it. Except for a ornery Idle Air Control it's run as well as a brand new car. I'm very pleased with how well the rebuild kit has functioned. Thanks so much for your great pictures. I wasn't present when Tom rebuilt mine, so it's very interesting to see how it's assembled and how it looks in it's exploded views that you photographed.
Re: Rebuilding a tbi and things in pieces
Sunday, April 21, 2013 9:08 PM
Thanks and once I get the kit to do this rebuild I will make I hope a short video explaining the steps etc to make it new again.At least the injector and IAC look ok so keeping those as it is a back up and will spend the dough if needed to update those if and when needed.

Re: Rebuilding a tbi and things in pieces
Tuesday, November 12, 2013 8:33 PM
Just a update.I am working on a another spare tbi for mike(wagon) and just have to get something for it before I post some pics of the before/after not rebuilt,but,he needs a spare so he can redo his or heck maybe use the one I plan on sending his way.I do have the other spare yeah still in pieces and just need the kit so I can actually finish it maybe this week,time pending.Just doodling around and figured time for some new info or things of interest.PICS are to be shown soon!!!

Re: Rebuilding a tbi and things in pieces
Wednesday, November 13, 2013 5:00 AM
Great job!
If you can, post part numbers and sources for the parts when you do the pics.

Like Orlen said in a past post this stuff was cutting edge back in the day. For us carb guys it was intimidating, ooo fuel injected tbi. Really nothing more than a fancy carburetor. Tbi was a hell of a lot easier than pulling out a choke switch on the dash on those cold -25 degree days. 29 years later my old cavs will still fire right up and keep running with the old dirty tbi. So a rebuild would be a good thing to do, just to replace the old gaskets and give the tbi a nice fancy shine inside and out.

Re: Rebuilding a tbi and things in pieces
Wednesday, November 13, 2013 6:33 AM
When I did mine this summer on my 1.8, I bought a new injector from Autozone. Their computers had the wrong part number, and I have no idea what the correct part number would be.

I just put my old injector back in and everything was fine. Of course that was after hooking up the new injector and having it dump so much fuel it would flood out the engine as soon as it started.
Re: Rebuilding a tbi and things in pieces
Wednesday, November 13, 2013 5:05 PM
I have to say many, many parts on the J's have really stood up very well to the test of time and durability. The Throttle Bodys are especially true of this. Carburetors couldn't hold a candle to the life of these. How many rebuilds would a carb need in 30 years? I would have never guessed that the electronics would have held up as well either. I have spare computers for both my cars with little expectation of ever needed them - just piece of mind. Seems the weakest links in the chain happends to be the Ignition Control Module or the Fuel Pump - a simple $20 and $40 part. Not bad for that "Cutting Edge" Technology 30 years ago. Kinda make one wonder how they strayed so far from the beaten path?

Oh by the way - the old Wagon passed her 13th State Inspection under my stewerdship today. Wheeeeeee

My daily driver get another year on the roads!!

I still see quite a number of daily driven 1st gens around where I live. Mostly Chevys. I bet we have a great many folks out there pass by J-Body and visit but not be a member.


Re: Rebuilding a tbi and things in pieces
Thursday, November 14, 2013 8:21 AM
Great Thread.

Back in 1990, I was having my engine replaced in my 84. The guys doing the work were justifying the expense by saying "this was race car technology only 5 years ago" when referring to the turbo setup. It is funny how what once was so intimidating is now something we happy immerse ourselves in.

Time flies and technology changes. As long as we are open to new things and willing to try, our potential to learn is without limits.

Keep up the great work!

Re: Rebuilding a tbi and things in pieces
Thursday, November 14, 2013 10:37 PM
Ok now to explain things.the above tbi was filthy and was cleaned with ivory soap and degreaser and polished with some FINE brushes on my cordless dewalt.Now the problem was the 2 small screws on the butterfly very tight and broke one,but removed and used the better throttle arm even though I can use the original.I went to ace hardware and found some 3x48 1/4 FINE thread screws to replace.I installed the new ones and shots of the said screw and installed and used blue Loctite to keep in place(Phillips head).Ok now the intriguing part on rebuild kits.If you buy a kit it comes with all the gaskets,and even the fuel press regulator gasket BUT not the tension spring.If you buy the kit from auto zone cost 34.99 but if you want the FPR kit which has the rubber diaphragm plus gasket which has two or three more items which are in the regular kit(IDK WHY) and yeah the precious spring.SO Stupid just to get FPR kit so you can just buy it for the SPRING!!!! The normal kit comes with everything BUT the spring????? I checked with advance they sell the kit for 44.99,oriellys same price and sold as I said above.All three stores sell the same kits with what you need aside from the fpr spring and in short you can spend lets say 44.99 for the rebuild PLUS 34.99 fpr kit almost 80.00.I do not think I would want to rebuild my whole tbi minus a new spring being the old spring has lost tension and I have not dug into what exactly the springs tension strength is just yet to check a old one to see if still in specs.I may list the auto zone and advance auto links to the TBI kit and the FPR kit both so you can see how silly this really is.BTW this fresh clean part is for mike (swaggin wagon) and I held off on buying a kit for my other spare till I look at the spring part idea on strength testing it,over buying a kit just to get just this part as the full rebuild kit comes with EVERYTHING you need aside already.Your local J body investigation tbi guy.

Re: Rebuilding a tbi and things in pieces
Thursday, November 14, 2013 11:04 PM Ok here are the tbi kit and fuel pressure regulator kits so you can see the goodies you get.As said the fpr kit your soley buying for the spring really.I will check napa and see what they have.Auto zone is the lowest cost over advance or oreillys on the tbi kit being 34.99 versus 44.99.I hope this works right I tried several times to get the links and had errors and yeah I did preview it.

Re: Rebuilding a tbi and things in pieces
Monday, December 02, 2013 5:10 AM
You can find the kits with the regulator diaphragm on ebay.
Re: Rebuilding a tbi and things in pieces
Saturday, December 07, 2013 7:49 AM
Hey Ron,
I'm looking for a 2.0 throttle body to rebuild for my '85 Wagon. If you can find anything, shoot me a price and I can get the money to you.
This is definitely the next project for my Wagon...!

~ Mike ~

Re: Rebuilding a tbi and things in pieces
Wednesday, December 11, 2013 12:01 PM
I was screwing around on the internet and found this video where a guy rebuilds a GM early 90s V8 throttle body and he installed this adjustable fuel pressure regulator on the throttle body:

I wonder if this can be used on my '85 throttle body ?

Here's a link to the video:

I'm going to call this CFM-Tech and see if this kit can be used on my car because I think dialing in the fuel pressure would really maximize my fuel mileage and performance !

~ Mike ~

Re: Rebuilding a tbi and things in pieces
Thursday, December 12, 2013 10:53 PM
I watched the video and while I know how to rebuild one and CLEAN one up really nice and install.My thoughts on the adjustable fpr in a four cylinder would seem pointless to me.Reason I say that is because our cars are already very efficient and the computer adjust based on how the car is operated.I will not say that you could tweak it a touch but consider that the v6/v8 models are not as fuel friendly and those tend to need let's say some personal tweeking to achieve how you drive the ride.I think I would not alter this due to it is a four banger and these do pretty solid own there own with out intervention.The best I had on mileage was 34mpg hwy and around town idk cannot recall but def mid 20s.It would not take much to make this happen but,for the cost over real benefit is 50/50 imo.If the price is not too out of line say under 45 bux maybe worth trying.I am more of a stock person and if it solid as is why doodle with something that is solid as is.Some may agree or disagree with my thoughts but,being my experience with these cars they are pretty good minus some mild things but gm did pretty good considering it for the 80s.Done the one item I do want to add is the inline adapter for the fpr with a Schrader valve since all the 4 cyldrs minus the turbo cars did not come with said item.That item can be bought for under 10.

Re: Rebuilding a tbi and things in pieces
Saturday, December 14, 2013 5:42 PM
got mine on ebay, but its almost too short , its only in a couple of threads so don't wrench on it, I installed mine for testing and then removed it and put the stock bolt in, I really didn't trust it for long term use being in so shallow.
M12x1.25 thread Gauge
Re: Rebuilding a tbi and things in pieces
Saturday, December 14, 2013 11:07 PM
Shannon they make new pig tails for the injector harness or rather it comes as a whole new plug with wiring extra length.I replaced mine as the plastic becomes very brittle.I would have to dig back in another thread with all the specific part #s to find but I know advance def sells it and fairly easy to locate in the tbi items I think.I just noticed yours a touch yellowed and they do get hard and a cheap piece of insurance to a rebuild.

Re: Rebuilding a tbi and things in pieces
Saturday, December 14, 2013 11:17 PM
Gp Sorenson 800-8225 for the injector harness from advance Shannon.I would double check it tho.

Re: Rebuilding a tbi and things in pieces
Sunday, December 15, 2013 6:48 AM
thanks, I've had it on and off prolly a hundred times since I got the car doing troubleshooting and all, Its still pretty flexible and I'll keep those numbers for a replacement handy.
Re: Rebuilding a tbi and things in pieces
Tuesday, September 22, 2015 10:06 PM
I am reviving this thread for John (84 verts) and the gp Sorenson tbi kits for $34.99 claim they have the fpr but(I did not see It).I will say for the 84 gp kit is 96-617 NO ? but I did not see the FPR (fuel pressure regulator in the kit) even though it says it has said parts?I sourced this thru auto zone for the kit.I could link it,but tired I am however I took the day OFF.I talked with john today and I may revisit the auto site as the TBI kits are getting finicky on what they have.I did not see the fpr gasket OR spring and if your injector being a Single injector is as said is spraying uneven or dropping fuel in big drop's it is running Rich for sure.Let me be specific here on the TBI 1 injector cars IF the fuel injector is dripping fuel,spraying Unnormal it probably is worn out and dumping fuel and causing it to run rich or uneven.I will say these TBI units DO NOT require any gasket sealants and I tighten downed the component by hand(no torque wrench).Just tight as over tightening these small bolts will break them imo.

Re: Rebuilding a tbi and things in pieces
Wednesday, September 23, 2015 4:29 PM
Thanks for the info Ron. Hopefully this will help with the idle issue.

Re: Rebuilding a tbi and things in pieces
Wednesday, September 23, 2015 7:36 PM
John I would buy the fpr kit as it come's with the NEW spring and other items that Are not included in the tbi kit.The link with both the kits are above.I also checked and auto zone does sell the Air cleaner temperature sender for $62.00 and I would go ahead and do this.I think since your idle Is camming this can affect it especially on a cold idle.Plus clean your IAC valve as well.Any further questions just ask.

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