Throttle Body rebuild

Jones183 · Sep 20, 2022

94 GMC single cab short bed manual 5 sp.
I am really having to restrain myself, I could really spend alot of money fast on my truck. I want to rebuild my TBI and replace the injectors but I cant afford to do it all right now. My question, is there a big benefit to rebuild the TBI now without replacing the injectors or should I just wait until I can do both at the same time. It runs ok just has hesitation and seems to bog down when I give it gas to get on the interstate. I am pretty sure nothing has ever been done to it in the past so it all is 28 years old. I did a complete tune up last week, it helped some.
Thanks in advance for your opinions

Jones183

Brandon_Lutz · Sep 20, 2022

Yes, if it is has never been rebuilt, odds are the gasket for the fuel pressure regulator is probably starting to break down/collapse and let excess fuel get by it. The rebuild kits are fairly cheap and it is an easy job to do.
You could also get the injectors cleaned while you have the TBI apart. Here is one way of doing it yourself. (Video not made by me, just a easy to follow video I found online.)

How to clean TBI Injectors

I replaced my injectors with new ones and plan to clean my old injectors and keep them as spares

PlayingWithTBI · Sep 20, 2022

Jones183 said:
It runs ok just has hesitation and seems to bog down when I give it gas to get on the interstate.

Check your fuel pressure 1st. It s/b 11 - 13 PSI. I know GM specs 9 - 13 but, IMO <11 isn't enough.

tayto · Sep 21, 2022

an often overlooked repair is throttle shaft bushings. it is standard procedure when I "rebuild" one, as most I see have wear here. sometimes the wear is to the point the throttle shaft sticks in the bore. I use oilite bushings and a drill bit I bought from Cliff's Performance.

Jones183 · Sep 21, 2022

Thanks so much for the advice I will see what happens. That is what I sort of thought, just wanted some input from the guys with more experience on these trucks. Knowing the full history of this truck I would bet nothing has ever been done at all since new so I guess it is running as good as it can and hopefully it will greatly improve when I finish. Thanks again

Jones183 · Sep 21, 2022

tayto said:
an often overlooked repair is throttle shaft bushings. it is standard procedure when I "rebuild" one, as most I see have wear here. sometimes the wear is to the point the throttle shaft sticks in the bore. I use oilite bushings and a drill bit I bought from Cliff's Performance.

Are they something that is easy to find? I cant seem to locate them. Is that name what i search for?

tayto · Sep 21, 2022

3/8″ Throttle Shaft Bushing Kit – Cliffs High Performance Quadrajets

tayto · Sep 21, 2022

i do about a half dozen TBI units per year. it will also fix Qjet secondary shafts, holleys and I can even repair TPI/LT1 throttle bodies with it. I understand for the average DIY'er this is expensive, but can fix a common wear point and potential (big) vacuum leak. it is also cheaper than a remanufactured unit. I usually charge $50 canadian to do the repair.

highwaystar · Sep 22, 2022

Rebuilt mine this summer, sent injectors to "Injector Rx", they cleaned, flow matched & sent me the flow chart. Good turnaround.

89RCLB · Mar 31, 2023

Gonna rebuild the TBI on my GMC this weekend. Question is, is a bath in Chem-Dip overkill? Or just stick with a good cleaning using an aerosol cleaner?

Thanks.

Throttle Body rebuild

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