I have a TBI 350 out of a 1989 GMC C1500. I am thinking about putting it in my 69 GMC but there are some wires I know I can eliminate (like the electric speed sensor etc.) I have the wiring harness, ECM, All the sensors still on engine, Fuel tank with pump. Where can I find a schematic so I can figure out what I will need? One other question, I assumed this truck had a 700r4 tranny, being an 89 model, BUT after pulling it out it is a turbo 400. It doesnot have the TV cable but has a vacuum line hooked the intake, It also the electric kick down like a turbo 400 and that is the ONLY electrical connection on it. The truck was being driven daily until hitting a tree and ultimately killing the driver, my second cousin, but since this truck had a 400 and my 69 has a 400 then I wont have to do anything to the ecm will I? I assume it was already done. But I do need info about how to hook up the harness in my truck if anybody has a diagram or other info it will be greatly appreciated.

Ah, just came over here from seeing your post in general disscussion :)

Ok, I've got an 89 chevy half ton as well, and really, there isn't a lot to remove from the harness. Basically, it'd be the TH400 kickdown, and if the 89 has a smog pump, and you wish to remove it, the air divert solenoid wiring. If TBI controls the TH400's electric kickdown based on the throttle position sensor. When you hit a certain TPS percentage, it clicks a relay on that kicks the tranny down. You can simply unpin that wiring and use your factory wiring if you wish.

Other than that, you pretty much need everything that'll be on the TBI. Make sure that you install a VSS though, thats hugely important to the proper operation of your truck. I cannot remember directly off hand, but I do believe that a TBI needs a 2000 pulse per mile VSS, which can be produced by installing an inline sensor between your tranny and speedo cable. Other than that, your TBI engine should have most of what you need as far as sensors and stuff go.

As far as installing it goes, its actually pretty simple. You'll need to provide an ignition power source, and a constant power source for the ECM, injectors, and a few other things. Just get an aftermarket ATO type fastburn fuse terminal, and set yourself up a little fusebox just for the TBI. Run your wiring, and you should be in buisness pretty quick.

Oh, just remembered, if you do plan on removing the smog pump (if so equipped) or the EGR (I wouldn't recommend it myself) you'll need a new prom burnt for the ECM, which is a pain in the butt, and would cost you about 50 bucks.

If you run into any snags during the install of the TBI, send me a PM, and I can give you a hand.

If you need any wiring, go to www.chevythunder.com click and click on the TBI section, then choose the 1227747 ECM, which is what your 89 will have. That wiring diagram will have a few things that your truck probally doesn't have, don't worry about them, and just ignore them :)