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TBI to Carb Wiring HELP PLEASE

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Old 03-07-2007, 04:48 PM   #1
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Question TBI to Carb Wiring HELP PLEASE

I have a 1991 S10 that had the 4.3 L fuel injected engine. I am swaping it for a 1980 chevy 350. Do I just cut and modify the factory wiring harness or does someone sell a replacement wiring harness? Also, what to do about the gas tank? The original tank had the fuel pump in the tank of coarse. Do I need a different tank or should I just mount a new fuel pump outside of the tank? Any help will be appriciated. Thanks
Old 03-07-2007, 06:50 PM   #2
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Re: TBI to Carb Wiring HELP PLEASE

I will make you a v8 harness out of what you have.$$
Old 03-07-2007, 09:49 PM   #3
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Re: TBI to Carb Wiring HELP PLEASE

Painless has wiring. It would be nicer then cutting. You could use your intank pump but need to regulate it down to about 7psi. Or get rid of the intank pump. I have the pickup/ fuel level sender out of an 84 carbed that may work in your tank. Just cost ya shipping.
Old 03-07-2007, 10:08 PM   #4
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Re: TBI to Carb Wiring HELP PLEASE

1. Brown wire: goes to the brown wire in the plug on the alternator. This wire is for the check battery light in the dash.
2. The green wire goes to the temperature sending unit
3. The large gauge red wire: Connects to the output stud on the alternator. This wire provides power for the fuse panal.
4. The positive battery termainal needs to be connected to the output stud on the battery with large guage wire. A large gauge wire also needs to be run from the positive battery terminal to the positive terminal on the starter.
5. The purple wire: Conncts to the starter solenoid. This wire is only hot in "crank".
6. The medium gauge pink wire: Goes to the pink wire in the plug on the ignition coil. This wire is hot in "run" and "start" only and provide power for the coil.
7. A wire needs to be run from the white wire in the plug with the pink coil wire from above to the "signal" wire for your tach. For information on modifying your stock tach to work with a v8 look here Recalibrating your S10 tachometer for a V8 .
8. The pink wire: Needs to be wired to the pink wire from the alternator that is in the same plug as the brown alternator wire. If you're running fuel injection the pink/black wires for the computer can also be wired with these wires. If you're not running fuel injection you could forget about this pink wire and just wire the pink wire on the alternator right onto the output stud on the alternator.
9. Orange wire: An always live wire used for the fuel pump relay and fuel pump. This is wired to the orange fuel pump relay wire and can also be used as an always live sourse for your ecm. If you aren't running fuel injection it would be agood power source for a smaller cooling fan or anything under your hood that needs to be always live.

this for 2.5 but might be the same or really close. Pretty much every wire that goes on the pass side of the firewall will be cut off.
Old 03-08-2007, 08:38 AM   #5
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Re: TBI to Carb Wiring HELP PLEASE

No after market harness will look any different than the stock harness..The cut wires will be pulled completly off the truck,and the painless you still have to splice the wires in.I havent done but about 25 of these trucks. QUOTE FROM DP::""Pretty much every wire that goes on the pass side of the firewall will be cut off"".that is exactly how it will have to be done if you want to get rid of the wires.You dont need to do anything to the fuel pump,just unhook it leave it alone.Use the original fuel lines,hook them to the pump and thats it,no need to get a regulator unless you plan on building a 500 hp drag motor.When the in-tank pump has to power to it,the plunger will remain open.so therfor leave it in the tank or pull it out,whatever,but you dont need a regulator.last time I will say this,unless you have a high hp motor.
Old 03-08-2007, 03:10 PM   #6
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Re: TBI to Carb Wiring HELP PLEASE

Why would you want to take a 14PSI pump and only regulate it down for 500HP and not for a lesser motor that only needs 7?

Oh and I have used painless in swaps and did not have to splice any wires. Did have to change ends before was able to remove the pins and only replace the plastic retainer.

Last edited by MadMikeZ28; 03-08-2007 at 03:13 PM.
Old 03-08-2007, 04:47 PM   #7
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Re: TBI to Carb Wiring HELP PLEASE

Quote: Originally Posted by MadMikeZ28
Why would you want to take a 14PSI pump and only regulate it down for 500HP and not for a lesser motor that only needs 7?

Oh and I have used painless in swaps and did not have to splice any wires. Did have to change ends before was able to remove the pins and only replace the plastic retainer.
Im not saying regulate the fuel down for 500 hp motor,I said you can leave the pump in there and not worry about it unless you have a 500 hp motor.As far as the painless for a s10 swap,thats a waste of money,use what you have already.
Old 03-08-2007, 08:28 PM   #8
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Re: TBI to Carb Wiring HELP PLEASE

Quote: Originally Posted by s10-den
Use the original fuel lines,hook them to the pump and thats it,no need to get a regulator unless you plan on building a 500 hp drag motor.
I know what I read
Old 03-08-2007, 09:59 PM   #9
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Re: TBI to Carb Wiring HELP PLEASE

Yea,I didnt TYPE what I was thinking.but anyway,dont buy a painless wiring and dont buy a regulator,you dont it UNLESS YOU HAVE A 500HP ENGINE AND A BIG ELECTRIC PUMP.

Last edited by s10-den; 03-08-2007 at 10:06 PM.
Old 08-05-2010, 01:13 PM   #10
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Re: TBI to Carb Wiring HELP PLEASE

Quote: Originally Posted by dbprecision2002
1. Brown wire: goes to the brown wire in the plug on the alternator. This wire is for the check battery light in the dash.
2. The green wire goes to the temperature sending unit
3. The large gauge red wire: Connects to the output stud on the alternator. This wire provides power for the fuse panal.
4. The positive battery termainal needs to be connected to the output stud on the battery with large guage wire. A large gauge wire also needs to be run from the positive battery terminal to the positive terminal on the starter.
5. The purple wire: Conncts to the starter solenoid. This wire is only hot in "crank".
6. The medium gauge pink wire: Goes to the pink wire in the plug on the ignition coil. This wire is hot in "run" and "start" only and provide power for the coil.
7. A wire needs to be run from the white wire in the plug with the pink coil wire from above to the "signal" wire for your tach. For information on modifying your stock tach to work with a v8 look here Recalibrating your S10 tachometer for a V8 .
8. The pink wire: Needs to be wired to the pink wire from the alternator that is in the same plug as the brown alternator wire. If you're running fuel injection the pink/black wires for the computer can also be wired with these wires. If you're not running fuel injection you could forget about this pink wire and just wire the pink wire on the alternator right onto the output stud on the alternator.
9. Orange wire: An always live wire used for the fuel pump relay and fuel pump. This is wired to the orange fuel pump relay wire and can also be used as an always live sourse for your ecm. If you aren't running fuel injection it would be agood power source for a smaller cooling fan or anything under your hood that needs to be always live.

this for 2.5 but might be the same or really close. Pretty much every wire that goes on the pass side of the firewall will be cut off.

can you make it any easier?!?!
Old 08-05-2010, 01:49 PM   #11
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Re: TBI to Carb Wiring HELP PLEASE

ok i just went from tbi 350 to a carb several months ago...


DONT cut every wire from the pass side firewall!

Once your intake and efi and all the junk are off your engine, take all the loom off the engine harness and lay it over your intake area, separate the alt wire, starter wires, oil pressure, temp, and several others i dont remember, but basically, take each sensor plug: eg- map, tps iac etc etc and cut each lead off at that main harness loom the runs behind the engine. It will be easy to see what wires you need to keep and which to throw away with it all opened up.

For the love of god dont take your pump out of your tank. Get a RETURN style regulator regulated at 7 psi and RUN AN IGNITION LEAD from the dist area over to the FUEL PUMP RELAY. That will turn your pump on when you turn your ignition on. Converting to a manual pump is DUMB when you already have a whole return style electric fuel system already there!

fuel pressure regulator part: http://www.summitracing.com/parts/HL...5&autoview=sku

Then you need to run a switch inside for your torque converter lockup.
Cruise controll will still operate as factory since your speed sensor and drac dont go THROUGH your ecm.... Nothing needs changed there. Pull your ecm fueses, you dont need your ecm powered up any more.

other than that, there are no real tricks, you wires your previous coil power wire to your new hei coil. thats about it.

Let me know if you need any help with the ac if you have it and it quits working...

Last edited by superbee; 08-05-2010 at 01:53 PM.
Old 08-05-2010, 11:04 PM   #12
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Re: TBI to Carb Wiring HELP PLEASE

does any one know where i could find a wiring schematic?
Old 08-06-2010, 12:14 AM   #13
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Re: TBI to Carb Wiring HELP PLEASE

A: yes i could get one...

but B: you dont need one.... Trust me.

I know it sounds scary but i promis when you lay the wires out with the loom off, you can no doubt tell what wires went to a sensor vs the ones you need.... The alt heavier gauge wire with an eyelet on the end, you know what that looks like vs the injector wires with the plastic housings on the end... its stuff like that, you should have any trouble chipering it out. If you do have a question, take a pic of the wire and we can tell you.
Old 08-08-2010, 09:53 AM   #14
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Re: TBI to Carb Wiring HELP PLEASE

listen to superbee!!!
Old 08-08-2010, 02:14 PM   #15
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Re: TBI to Carb Wiring HELP PLEASE

:banana:
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