1989 tbi chevy k5 tbi & ign. Wiring mess, - Hot Rod Forum : Hotrodders Bulletin Board
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Old 03-05-2019, 06:44 AM
prewitt090416@gmail.'s Avatar
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1989 tbi chevy k5 tbi & ign. Wiring mess,

89 K5 blazer TBI sbc . I find myself throwing my hands up more than not on this little big project truck....b4 reading take into consideration I'm no pro with electrical side of things, once it gets more then these TBI fuel injection electric fuel pump I turn around for my 78 Monte with the SIMPLE roots..so..I live here in Ken-tuck-aye so y'all get an better idea of situation . I don't got a garage I live in a trailer park that don't condone vehicles setting broke dwn nor do they allow major overhaul/ large scale messy mechanics/ or good ole fashioned slangin grease n knuckle bustin./ ..(champagne taste , M.D.20/20 budget community here)
first off, was told engine was replaced (reckon other threw a rod)
Truck was ran as some kids "Mud Toy" .
He then parked under the infamous "shade tree"
...n now I bought the results....

So there's wires and clips and wire looms with no apparent home to them providing dead ends for me thus far.. I've got the injectors on top but then, my bracket holding the sensors is were problems begin.
The little blue wire that clips in at bottom-side of tbi can't recall what it's called right off hand. (?) *clip there, but, then CUT* ..?..

Then, the entire ac system has been deleted. (I mean everything's gone exposing hole in firewall) so those wires are staring back at me donating to my confusion lol.
The "aux blocks" (lack of proper word) that can be located on fire wall with 12v ignition etc. wire been yanked off and left behind , under the "assumed Shadiest-Shade-Tree in Shade-ville USA"
And also on the factory style distributor, the double clip for the outer ignition coil setup I got it in as it should be,wire clips in place ..but no clue as to the where-a-bouts' of the rest of wire
(they been cut 4in. Above the attaching white&grey/black clips and theres no obvious "suggestive" wire to choose from to tie back into as once was. My guess is gone so I'm depending on opinions here everyone.

I guess I'm asking for a basic way to simply get this situated here with what's already here, on truck.

I just want the thing to start n run without catching fire lol. Don't need be factory specs style job. Any help appreciated greatly.

There was 5 damn toggle switchs on the dash that no longer have anything at connection points on them (can only assume they must had been for "nos" or the 007 style influenced "flipping 2nd incognito liscense plates used for get aways) 🤥🤥😑😆 haha

Now I have a old cast iron intake as well as a performer Edelbrock intake and a qjet and a Edelbrock carb laying around as well as a spare hei distributor. That sounded like an easy way out but wanting to utilize wat is existing in truck just need direction to do so. Thx again in advance. Ivtryd to cover all best I know how. Sorry if confusing to you it must mean it's got the best of me 1st lol!!

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Old 03-05-2019, 06:52 PM
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This will run your stock tbi engine stand alone.

Click on the option to use there ecm having there chip installed and your transmision.

This removes your factory low oil pressure fuel pump shutoff so a inertia switch is recommended to power the fuel pump relay.

Comes out to $460 plus shipping.

This is a plug and play thing.

You will be left with the steering column wiring, lights, heater and so on not related to the engine.

Call them with questions.

If you dont want the option the carb has been done. I would not mess with a intake at all on tbi heads just use a tbi to carb adapter, large distributior and a return style fuel pressure regulatior.

You can retain the low oil pressure shut off to turn on the relay for 2 seconds then keep it on above 6psi. That is not computer controlled all pressure switch based.
Or install a inertia switch when the key is turned on tk power the pump.

Tbi is a very good system. But i been there playing with 3 or 4 fuse boxes under one hood with wires and switches going to nothing.

If the stand alone is not for you you can buy a entire harness and hook it up to your ecm. But the cost diffrence is going to be minimal with a good amount more work involved.
If you have a manual it is not that horrible but i would still look at the stand alone or carb as a option.
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Old 03-06-2019, 12:20 AM
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Unfortunately there is no simple nor cheap way out. My basic recommendation for anyone with limited means in tools, work area, finances is to never buy anything newer than 1986, that's the last year of carburetors and HEI. When EFI, which is pretty reliable until it either fails with old age or somebody as in your case carves it up the road to restoration or replacement is complex and expensive.

For a carb conversion:
The heads on that engine do not accept older intakes. GM changed the angle of the intake bolts along side of the plenum. You need to either egg those holes in older versions or buy something like the Professioonal Products or ProComp intakes which come with adapters to fit the 86 and older heads or the 87 through 95 heads by flipping the adapter over.

For the fuel supply you need a bypassing type regulator, necessary fittings to fit the 3/8ths pressure lines from tank and to carb, and fittings for the 5/16th return line. Plus an inline fuel pressure gauge so you can see to trim the pump pressure from 12 to 15 psi down to a carb friendly 4 to 5 psi. The bypass regulator is to keep fuel flowing through the pump to cool its motor otherwise it will burn out in short order. You can find inexpensive bypass regulators that work well off EBay for a lot less cash than the name brands, stay away from anything using AN fittings as this stuff is unnecessarily expensive. There is a relay either on the firewall or fender that operates the pump, pry the connector apart and connect a hot wire to the gray wire leaving the relay, this will bring up the pump and fuel gauge. Wiring through the oil pressure switch will not work for safety as the computer does the count down, you will have to pick up an analog version at the parts store.

For a distributor a standard HEI can be used, you will need to supply it with a switched 12 volts.

You will find the little stuff like a carb throttle return spring, plumbing the heater and bypass will be a pain in the butt, as will be all the little details. You can't just go cutting wires as the computer stuff and the housekeeping stuff are in those bundles, so teasing the wiring mess out to clean things up takes good wire manual and patience.

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Old 03-06-2019, 04:51 AM
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Any chance of getting a complete used wiring harness for the engine? I've done a lot of wiring on my projects and and it doesn't need to cost a fortune.

I use the diagrams in a Haynes manual to track them down. They are not perfect, but they are pretty good. You can google drawings as well.

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Old 03-06-2019, 06:42 PM
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Witt do you have a manual or an automatic?
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Old 03-19-2019, 06:42 PM
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Thanks man, that was a question I had in my mind was if they made a TBI to carb adapter plate for bolting a carb onto this intake . That seems like my best bet. I'm just teetering on the decisions of useing wat is here and figuring it out and ultimately ending up with balding head lol or just install what I'm more "confident" in dealing with , thanks everyone.
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Old 03-19-2019, 11:09 PM
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Two barrel Holley to TBI intake.


You'll need a bypassing regulator to cut the TBI pump 15 psi down to a carb friendly 5 psi, a gauge and fittings to read that pressure. EBay is a good place for such a regulator at an affordable price. An HEI distributor which like the fuel pump you'll have to wire up.

The pressure line to the TBI is basically 3/8ths, the return is 5/16ths. They are actually metric but those US sizes will connect, you'll probably have to cobble some adapters.

The pump uses a gray wire out of the relay that is either on the firewall or the drivers inner fender, just pull the connector and plug into the gray wire that will run the pump and fuel gauge.

I'd just run a new hot wire for the HEI. If you wish put in a dual pole, dual throw switch on the panel to supply 12 volts to the pump and HEI from a fresh fused source. A safety switch for pump is a good idea, There is a GM 3 contact switch that screws into an oil pressure port. It is a closed and open switch, when the starter is engaged it provides fuel pump and cranking. Once the engine fires and you stop cranking it opens that circuit and closes another with oil pressure to keep power on the pump. In the event lost or interrupted oil pressure the power to the pump is shut off.


Last edited by BogiesAnnex1; 03-19-2019 at 11:34 PM.
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chevy, ignition, sbc, tbi, wire harness

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