TBI rebuild completed!

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Maryland
First Name
Matt
Truck Year
1990
Truck Model
Chevrolet Suburban 1500, 4x4
Engine Size
5.7 L
Hi everyone,

Happy Monday!

I successfully rebuilt the TBI on our 1990 suburban over the weekend! Wow, what a difference. I recommend do this for anyone with a TBI that's running a little wonky. It's not hard, and not expensive. Plenty of great demos on youtube, etc.

A couple things came up. First, after the reinstall, I could not adjust base idle below 1160. This is still a mystery. While pursuing the idle problem, the following day, I found the drivers side injector leaking badly on the top. After searching around about this, I determined the upper 0-ring was leaking. Upon removal, this brand new 0-ring was totally split! Then I find out I should have lubed it with ATF or equivalent prior to install to seat it properly....well, we live and learn. After securing new 0-rings, and lubing prior to install, the thing runs perfectly....and I could set base idle without an issue.

Happy Motoring!

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Bright Idea

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Mike
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1990
Truck Model
V 2500 Suburbans
Engine Size
5.7
I am about to do the same thing. The manual I have talks about regulator adjustment. Obviously you replaced the regulator internals. Is there any regulator adjustment ? Di you replace the injectors ?
 

diesel_lv

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AZ
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John
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1987
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K5
Engine Size
350
I rebuilt my '87 3 yrs ago. Went through 4 packs of O-rings because I was using grease or something. It needs to be automatic transmission fluid. Once I used that, they slid right in. I replaced fuel pump and put in spring that raises fuel pressure to what it actually needs. Unfortunately now i need to replace throttle shaft seals, they have worn and bleed air in so idle increases sometimes. Anyone doing this just make sure you use ATF on the injector O-rings.
 

bucket

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I've found dielectric grease to work even better than ATF. No other kind of grease, just dielectric.
 

diesel_lv

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I've found dielectric grease to work even better than ATF. No other kind of grease, just dielectric.
That is what I was using that pinched 4 sets. I guess it worked better for you.
 

bucket

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That is what I was using that pinched 4 sets. I guess it worked better for you.

That's odd. It's what I've always used and never had troubles with it. The very first time I ever put the o-rings in, I used ATF and buggered one up. Dielectric grease worked great on the second try so that's what I used from then on out. Maybe I push the injectors in different or something.
 

Overland Suburban

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Tracy
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1989
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Suburban
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5.7 tbi
Yep there way simpler than a Carb! When I rebuilt mine it ran some better but didn't come to life until I changed the fuel pump.......if there is such a thing as a 350 TBI coming to life Lol
 

Kevro_N_Chevro

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Kevin Forbes
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1988
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V10 Suburban
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I have also rebuilt mine. Used die electric grease, from what other states here. Runs allot better than it did. However I do want to replace the fuel pump also. So I can update then


Sent from my iPhone using Tapatalk
 

austinado16

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Central Coast, CA
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Todd
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1990 w/307k miles on the clock
Truck Model
GMC V1500 Suburban SLE
Engine Size
5.7L TBI/4L60/3.42's
Nice job and thanks for posting those good photos!

I did mine about 5-6yrs ago, used the thicker gasket to get the injectors up out of the air flow a bit, and installed a fuel pressure gauge and an adjustable regulator.
 

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