build thread for 2.8 carb to chevy tbi.

[Lil-Pony]

!!!!!! My wire harness has no parkneutral switch input and im confussed on what i need to keep !!!!!!

 

[Kadams87]

still searching for a damn tbi
started pulling apart the wiring harness and removing the junk, hope i didnt need the AC signal and control since mine already works

The computer needs to know when you turn the A/C on because it will adjust the idle to keep the rpms up and prevent stalling.

!!!!!! My wire harness has no parkneutral switch input and im confussed on what i need to keep !!!!!!

If you aren't controlling a transmission with it, don't worry.

If you tell me what year and rig the harness and computer came out I can get you a complete wiring diagram for it...if you want it. I have done way too much work on custom GM TBI wiring.

Also, did you get a knock sensor? As for fuel pressure, 20 psi is more than enough for GM TBI 13-15psi is what they run at, a pump that runs 20 -35 is fine...so a 2.9 pump from a bronco 2 would be perfect.

 

[Lil-Pony]

the jnkyard said it was a 93 but the door says it was a 92, the wiring harness colors kinda match the 1227429 ecm but the ecm is actually a 1228062. should i just hook up the signal from the a/c. ill have to solder the wires back on. damn wish i knew this sooner, assuming only makes an a$$ of your self.
it came out of a s-10 (thats the pickup right?) and its a manual 2.8

 

[Kadams87]

the jnkyard said it was a 93 but the door says it was a 92, the wiring harness colors kinda match the 1227429 ecm but the ecm is actually a 1228062. should i just hook up the signal from the a/c. ill have to solder the wires back on. damn wish i knew this sooner, assuming only makes an a$$ of your self.
it came out of a s-10 (thats the pickup right?) and its a manual 2.8

Yeah, I believe you'll be sending 12 volts to the input on the computer when the A/C is on but I'll know that for sure when I get the wiring diagram in front of me to and save it to post.

 

[Lil-Pony]

Its low enough that non-fuel injection fuel hose can be used. I bet that's why you are asking

Thanks for the answer and yeah that's why I asked, also how did you go about attaching the return line to the smaller of the two metal pipes on the new filler neck. It looks like jbweld

Thanks for your help so far kadams

 

[Kadams87]

Thanks for the answer and yeah that's why I asked, also how did you go about attaching the return line to the smaller of the two metal pipes on the new filler neck. It looks like jbweld

Thanks for your help so far kadams

My experience with GM TBI is tuning and building my 92 Chevy with a SBC 413, never done GM in a Ford....yet. If it were me on this swap I would get a Bronco II 2.9 pump assembly from the JY and use factory lines to connect it all up so the return goes right into the tank like it would from the factory. As for adapting the lines up in the engine bay to work with the 2.8's throttle body those fittings can be had at a good auto parts store or a shop that builds lines/hoses. I can't remember the sizes off the top of my head.

I don't like using "Maybe weld" where it will come in contact with gasoline.

Besides if you use a factory BII pump assembly in your tank it can solve you fuel pump issue at the same time. If a 2.9 pump will run a 4.0 it will handle your 2.8 no problem

 

[Kadams87]

Really the only thing you need to pay attention to on the A/C diagram is the wiring for the A/C Relay. The computer controls A/C function so it can cut the A/C at WOT or when the engine temp gets too hot.

 

[Lil-Pony]

Can i also get an interior diagram for the ignition and stuff like that. There is a 8-10 pin conector that has the data pins and the crank input on it that dosent attach to the ecm directly

 

[cammeddrz]

Sounds like kadams is unaware that the 1984 has a waaaaay smaller fuel sending unit opening than the 2.9 trucks had, so the in-tank pump from a fuel injected rbv won't work in a 1984 2.8 tank

It also sounds like he is unaware that the pump you have is the same part number as a 2.9 fuel pump

 

[cammeddrz]

And for the record, the JB WELD was all rico. I had no hand in that

 

[Kadams87]

There is a lot that I don't know, thanks for enlightening me.

Here's the wiring diagram, you're mainly looking at the 3 Amp Crank fuse and the 10 Amp ECM Fuse.

 

[RICO9]

There's JB weld over real weld. I did that because I leak checked it after with some soapy water and it made a tiny bubble. It probably would've been fine since the return line is only seeing a couple psi and I leak checked it with 30 psi.

 

[Lil-Pony]

There is a lot that I don't know, thanks for enlightening me.

Here's the wiring diagram, you're mainly looking at the 3 Amp Crank fuse and the 10 Amp ECM Fuse.

thanks, these will help greatly. i see a wire for diag enable A9. what it this used for? also can i get a interior digram of a 84 2.8 bronco2

 

[Kadams87]

thanks, these will help greatly. i see a wire for diag enable A9. what it this used for? also can i get a interior digram of a 84 2.8 bronco2

Diag Enable on pin A9 goes to the ALDL port (pre OBD2). When shorted to Ground, it will make the check engine light flash out the codes that are set in the computer.

Here are the diagrams that I have.

 

[Lil-Pony]

thanks again hopefully this will shed some light on my issues