TBI to Carburetor and back...

[BurbanLife]

Yesterday I purchased my long awaited project. A 1990 GMC Suburban 2wd. The engine was rebuilt recently and the original owner opted to remove the TBI and replace it with a carburetor. After carefully looking it seems as if the TBI itself was removed and a carburetor slapped in it's place. A couple manifold spacers in there and the carb doesn't seem to fit it correctly. Can I go back to the TBI or is it even worth it at this point. Oh yeah, the service engine light is on aswell. I'm guessing due to all the wiring and such still being there. Despite that hiccup the body is in phenominal shape minus a paint job.

[68Timber]

I'd convert it back to TBI. Think the PO might still have it?

[BurbanLife]

I just spoke with him. He has the throttle body but, not the manifold.

[MalibuSSwagon]

Should be easy to find a manifold. Or put an adapter on the carb intake.

[BurbanLife]

I am wanting to swap in a 454 eventually so do you think I should just wait until then? I'd have to swap the harness then anyway right?

[68Timber]

I'm not a TBI guru but I wouldn't expect the wiring to be different. You could probably find a manifold for cheap if not free, so if you're going back to TBI you may as well do it now and enjoy it on the 350 until you're ready for the 454 swap.

[BurbanLife]

Originally Posted by BRUISER

I'm not a TBI guru but I wouldn't expect the wiring to be different. You could probably find a manifold for cheap if not free, so if you're going back to TBI you may as well do it now and enjoy it on the 350 until you're ready for the 454 swap.

Thanks for the help. I'll have to keep an eye out for a manifold.

[BurbanLife]

So come to find out the previous owner did not have the throttle body and I have decided to stick with the 350. Any suggestions on locating a manifold and throttle body without breaking the bank?

[68Timber]

Keep an eye on craigslist or ebay, I'd probably check the local pick and pull first. Craigslist is probably your best bet for finding it cheap.

[BurbanLife]

Is there anything else I will need to get in order to make the switch back?
I was under the hood yesterday and it looks like the sensors are still plugged in to the wire harness.

[93M6Formula]

Literally any TBI equipped vehicle will have what you need from 87-95, f-bodies, trucks, suburbans, blazers, vans, caprices etc. Most junkyards should have at least one laying around somewhere.

[BurbanLife]

Thank you guys for the info. The search begins...

[BurbanLife]

OK, so after more investigation. I've noticed my truck has a mechanical fuel pump. All the information I've gathered shows this truck having a tank mounted fuel pump. I am starting to think the previous owner did more than just remove the tbi unit itself....what to do what to do?

[Hoods69BadBowTie]

Yea that would make sense since I think a TBI fuel pump pushes at least twice as much fuel pressure as a carbed mechanical pump would. You can run a carbed motor with an electrical fuel pump just need a fuel pressure regulator. I would get a hold of the previous owner to find out more about that before you start tearing your hair out.

[68Timber]

He might have unplugged the original fuel pump and left it in the tank. Call him if you can, to save the trouble of dropping the tank to see. Also, the pump in the tank may be dead and part of the reason he put a carb on.

[BurbanLife]

I spoke to the original owner over the weekend. He said the intake manifold was swapped and TBI unit removed, distributor changed, and a mechanical fuel pump added. All the wiring and sensors were left intact as well as the in tank fuel pump. So I'm thinking at best I need a manifold, TBI unit, distributor, and fuel pump block off plate at the very least. This was all done 1,000 miles ago, when replacing the pistons and doing a valve job on the heads, so he says.