Wiring electric choke TBI to carb swap

[496bb]

I’m in need of a keyed 12v source for the electric choke on my Qjet that is replacing the TBI. I’m wondering if any of the TBI harness or smog pump harness could provide an easy keyed power source for this purpose, since all that wiring is right there on the passenger side of intake anyway. Truck is 87 454- I think the harness is a bit different than the small block version.

Not taking all the TBI harness out, at least not for now. But, will definitely not be going back to stock TBI.

 

[Ricko1966]

Are you going to run your intank pump still? If no you can grab the fuel pump feed wire from the fuel pump oil pressure switch. Possibly is the same switch as your dash switch,but not necessarily. You'll have to see if your truck has 2 oil pressure switches or 1.If you are keeping your intank pump you can piggy back a second relay off the fuel pump relay to power the choke. If you want to use option 2 ask some questions if you need to,you may fully understand it,other than don't share the same terminal 30 power grab terminal 30 power from the alternator B+ battery B+ starter B+ or the wiper motor. Another way would be add a ps 126 oil pressure switch run battery power to 1 terminal,the other terminal to the choke. Ps 126 will only provide power through when there is oil pressure. Another way is grab a common 4 prong relay from the parts store. On the bottom are numbers,hook battery B+ to terminal 30. Relay terminal 30 to choke. Relay number86 to ground. Relay number 85 to alternator exciter wire. That's terminal 1 in back of the alternator. All of these will provide choke power only when engine is actually running.

 

[Matt69olds]

Any of the pink/black wires in the ecm harness should be an ignition feed, protected by the 10 amp ecm fuse.

 

[496bb]

Matt, I see the smog pump has a pink/blk wire so that may be the easiest option. Found these wiring diagrams on another forum so I’m gonna drop em here for future reference. Says 88-98 but I think as far as the TBI it helps for my 87. If anyone has a diagram for 1987 454 TBI Burb I’d love to see it.

 

[Ricko1966]

Matt, I see the smog pump has a pink/blk wire so that may be the easiest option. Found these wiring diagrams on another forum so I’m gonna drop em here for future reference. Says 88-98 but I think as far as the TBI it helps for my 87. If anyone has a diagram for 1987 454 TBI Burb I’d love to see it.

In your first schematic there. The grey wire at the fuel pump relay would power the choke only with the engine running if you aren't using the ecm than that circuit would be a very close mimic of how gm did it factory on carbureted trucks. Using an oil pressure switch to turn on and off the choke. Even with the ecm it would still be close.

 

[mtbadbob]

Matt, I see the smog pump has a pink/blk wire so that may be the easiest option. Found these wiring diagrams on another forum so I’m gonna drop em here for future reference. Says 88-98 but I think as far as the TBI it helps for my 87. If anyone has a diagram for 1987 454 TBI Burb I’d love to see it.

Yes, you can use the two-wire harness for the smog pump, has ignition 12v.