TBI issue *UPDATE* and a mod

[496truck]

Can someone verify the GM TBI unit uses a throttle return spring that is wound around the throttle shaft? I was pretty sure that was the only return spring used but the previous owner put on a heavy return spring to try and fix a high idle. I fixed the high idle by replacing the idle air valve but I think the spring put pressure on the throttle shaft and now the shaft has a sticky spot as well. I can live with that for now but will have to look into a TBI rebuild or find a good replacement.

But I really want to know if the factory used an external throttle return spring on the TBI?

And does anyone know of a TBI rebuild kit? or throttle shaft bushing kit?

Is a TBI for a 4.3 the same or is it smaller? I have one of these kicking around...

 

[4X4HIGH]

No external springs were used. There is a return spring located on both sides of the throttle shaft. Someone added the external spring because of the wore out throttle body housing/shaft. You need to have the TBI bushed and then polish up the shaft to get rid of any burrs and you'll be good. I have a friend here who rebushes the TBI unit but it has to be completely apart already and the throttle shaft is needed for fitment.

 

[496truck]

That's what I thought. I couldn't remember my S-10 t body having a return spring but wasn't sure. Going through the new truck playing "find the f-ups" ran across the spring and it didn't look right. I'll PM you if I need to send it out but for now I'm gonna look for a good used one. Thanx!

 

[496truck]

Did some junkyard searching with almost disastrous results. In my local area, not only are FS Chevy trucks a RARE find, but anything with a TBI either had no engine or TBI removed already. The couple TBI units I found were locked up solid. So, no easy swap for me.

I had a spare 4.3 TBI saved from my last build. It was a bit oxidized, even a bit in the throttle bores, but the throttle shaft turned smooth and closed properly. This is good cause the TBI on my Blazer sticks open slightly. Now to rehash it.

I removed the injector pod, grabbed some WD40 and some carb cleaner and an old tooth brush and went at it. The bores cleaned up nicely and this also gave me a chance to clean out all the vacuum passages and the PCV passage which was caked up real good. I'll get some gaskets this week and I should be able to swap over my 350 injector pod and install the assembly on the truck. This should take care of my idle issues...

 

[496truck]

Pulled the TBI today and swapped over the injector pod. Installed the assembly with a t-body spacer as well. The spacer made a noticeable improvement in power. It's not tire shredding but IS an improvement. My idle issues are solved and the extra return spring is gone for good.

 

[TommyM]

Are you talking about a spacer under the throttle body, or the spacer that lifts the injectors up a little bit?

 

[496truck]

Yup, t-body spacer (between t-body and intake). Not an injector spacer.