tbi wiring harness

[babybluec10]

Hey. I'm relatively new to the squarebody community and was curious about some more knowledge on TBI conversions

my truck is a 75 c10 Cheyenne, and I bought it with no motor or transmission. I have found an OBS donor truck with a TBI unit and 700r4. I wouldn't mind making it work on a 305 I have in my garage, with the overdrive transmission as well.

I was curious if the ecm is entirely standalone, which is what I have heard but was skeptical. I do know that there are provisions on most harnesses to wire the 700r4 up, but was unsure if removing sensors or connectors like on the gauge cluster from the harness would mess with the ecm.

In addition to that, when wiring up the TBI in the truck, is there one main fuse panel that controls everything or is there a separate box for just the TBI

 

[vr1967]

I’ve got a harness from an 88 k5 Blazer 5.7/700r4) and it is stand alone. Will try to remember to get it out and get pictures. May have one from an obs too, but I believe there is another bulkhead connector on the obs harness.

 

[Originalthor]

You can make the tbi harness stand alone pretty easily. It's a matter of a few wires for power when key on and a fuel pump wire. Heres the link and process i used

TBI Connversion wiring and diagrams!

TBI Fuel Injection Conversion wiring using a GM TBI EFI system!

www.gearhead-efi.com

 

[babybluec10]

Thanks for the insight. As far as fueling goes would an external high pressure pump be necessary or would I be able to get away with an in-tank lift pump

 

[Originalthor]

Well if your donor truck has the intank pump and all the fuel lines that would be the way I would go. Cause you will need a return line now

 

[vr1967]

Here is a complete tbi harness from a square body Blazer with a 5.7/700r4. It is basically stand alone. Bolts to fusebox bulkhead connector as other engine harness does, and round grommet just down from ecm is where wiring goes back in firewall placing ECM above glove box. The rest is just engine connections and I believe one to the buss bar on firewall

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