1985 C10 with TBI

[MiniD]

I have a 1985 C10 that "had" TBI on it. Someone did some work on the engine a while ago and it never ran right after. A couple of owners later, someone decided to remove the TBI and install a carb. It still didn't run right, so they looked at the rockers and saw that it looked like a couple weren't moving right. They replaced the cam and it started purring.

So... now I'm sitting with a TBI harness that I'd like to remove. Much of it is straight forward but I'm hesitant to dive into the wiring that goes behind the engine to the fusebox/firewall connector. I'm just not sure what I'm getting into, there.

Is this a relatively simple snip and remove operation or is there some major surgery needed?

[chevmn]

85 should have an ECM, and probably still electronics (sensors, other controls). If it were me, I would remove the carb, and replace the TBI. Do you have a check engine light? Even though it probably runs better, very likely it is not right if it still has the stock electronics, and missing the TBI. It might have had other work done, but my experience is many think they can simply remove or bypass parts and get by.

[MiniD]

I do not have a check engine light. I was worried the fuel pump wouldn't work but it is still doing its thing.

I'm going to convert the electrical system over to a standard truck with no TBI. This will also significantly clean up 35 years of "stuff". I'll have to figure out what to do with the fuel pumps, though.

[Just call me Sean]

85 didn't come with fuel injection. Are you sure it isn't wiring for an electronic feedback carburetor?

[MiniD]

Yes, I'm sure. TBI. This system was on the truck until earlier this year. A regulator is in place with a return line prior to the carb. The wiring really looks to be factory including the mounting bracket for the ECM and the hole in the firewall (doesn't look cut after paint). The owner that bought it new <reportedly> said something about a TBI test vehicle or something like that. Sadly, he has passed away since. The glove box isn't original, so RPO codes. Overall... I'm not so worried about it. It's impossible to prove and I don't want it, anyway.

[chevmn]

Originally Posted by Just call me Sean

85 didn't come with fuel injection. Are you sure it isn't wiring for an electronic feedback carburetor?

Sean is correct....if memory serves the first year for TBI on pickups was 87. So it should have a electronic feedback carb assuming this is a factory engine. Probably 305 as the 350 was not available on 1/2 ton until 87 as well.

[Just call me Sean]

Switching a TBI to carb isn't done by just bolting on a carburetor. It takes a bit more.

[cdub2010]

The tbi harness is really simple to remove from the vehicle. I believe its not connected to anything else besides tbi, distributor and ecm. Since you have a carb now some one took care of most of the wiring, factory installed or not. Just locate the ecm, a silver box approx 9x6 inches under the pass side dash and remove everything hooked up to it.

[MiniD]

Originally Posted by Just call me Sean

Switching a TBI to carb isn't done by just bolting on a carburetor. It takes a bit more.

Not much more. You need to regulate the fuel pressure down and make sure the fuel pump has power. What else would you need in addition to that? Intake, Carb and cam have been replaced.

[MiniD]

Originally Posted by cdub2010

The tbi harness is really simple to remove from the vehicle. I believe its not connected to anything else besides tbi, distributor and ecm. Since you have a carb now some one took care of most of the wiring, factory installed or not. Just locate the ecm, a silver box approx 9x6 inches under the pass side dash and remove everything hooked up to it.

It still has wires going through the back of the engine wire bundle to the bulkhead connector.

I've bought a regular wiring harness for the truck. I'm going to install that and not worry about it. I also bought a new fuel pump for the Holly Sniper that came with the truck.

[MiniD]

Meant to post this but didn't notice the add attachments button...

[Just call me Sean]

Originally Posted by MiniD

Not much more. You need to regulate the fuel pressure down and make sure the fuel pump has power. What else would you need in addition to that? Intake, Carb and cam have been replaced.

Carbureted and fuel injected manifolds have a different bolt pattern so the intake is a special expensive one, or change the heads with the intake. Or butcher up a carbed intake to make it fit. No safety for the fuel pump so in an accident you could pump fuel all over the place. Distributor would need to be changed as the computer also controls it.

You should be able to switch to a mechanical fuel pump. The earlier blocks usually just had a block off plate.

[MiniD]

Originally Posted by Just call me Sean

Carbureted and fuel injected manifolds have a different bolt pattern so the intake is a special expensive one, or change the heads with the intake. Or butcher up a carbed intake to make it fit. No safety for the fuel pump so in an accident you could pump fuel all over the place. Distributor would need to be changed as the computer also controls it.

You should be able to switch to a mechanical fuel pump. The earlier blocks usually just had a block off plate.

There's an HEI on it, too. As for the bolt pattern... I'm not sure this speaks to an 85. Just saying.

There was a throttle body on it. It now has a carburetor. I'm not quite sure the point you're trying to make as to that being impossible.

[Just call me Sean]

I didn't say it's impossible, I'm saying your truck is butchered. Yes this applies to your 85 that's why I'm telling you. If it has center bolt valve covers it has 87 EFI heads, if they're perimeter bolts it has 85 carbureted type heads.

[MiniD]

Edelbrock makes a carbureted manifold for that, sir. Modifying a carbureted manifold designed for carbureted heads to accommodate the different bolt angle isn't difficult either. There's no butchering required. The conversion is actually quite easy... not difficult or insurmountable.

You sound aggressive or defensive as if this is some kind of competition that you need to win. The truck does not appear to be butchered, at all. It has simply had the TBI removed.

[Just call me Sean]

So which of those things has been done to your butchered truck? Does it have the expensive manifold (non butchered) or did someone wallow out the holes (butchered)? I never said the conversion was difficult, I don't know where you're getting that from. The fact that you're removing things that you say are factory installed is exactly what butchering is. I was trying to figure out what was done to your truck because it does sound like an interesting truck, so I guess I'm winning at that.

[MiniD]

Sigh... You're not really here to help. I get it.