Heres some history about the car and what Im doing.

Ok i recently picked up a 89 iroc but the wiring was swaped for a 4th gen dash harness and all the plugs where changed and some where missing. The car has a LS1 tank in it as well with a stock pump I assume.

Due to the hareness being in the state its in Im swapping in my old 85 Z28 harness as I know it works and all I have to do is re-run it and add the power locks wiring to it.

Heres my questions

1 - The 85 harness isnt set up for a electric pump so how would I hook it up??? Also do i have to run a return line as im going carb??? What would i need to swap it to get it to work??

2 - I have a power hatch and a spolier 3rd brake light. How hard is it to splice into the 85 harness to get them to work???

3 - What pressure regulator would be a good one to use for a carb set up??

If anyone can help me please do as i really want to get my car running again this year. Diagrams, pics old threads are all welcome here as I want all the info i can get. Thanks Ray

 

Whoa thee big fella! Let's step back for a minute, ok? I'm a very firm believer is the KISS rule - Keep It Simple, Stupid!

1) Does this 4th gen dash stuff work presently? I mean are gauges functioning, starter functioning, etc.? If that stuff was done, and done successfully, I wouldn't try tearing it all back out, OR trying to integrate a 1985 harness in with it. Sounds like in the end you'll end up with a huge mess of who knows what spagetti barf that you'll never be able to decipher.

2) We'll worry about 3rd brake lights, door locks, trunk releases and other misc not-necessary-for-the-car-to-run goods later - let's get a starting running car 1st.

3) Fuel pump - an easy fix, assuming the fuel pump works. 3 wires come from the tank, a signal wire for the fuel gauge sender, a ground, and a hot for the pump. If the pump works all we have to do is wire up a relay, so that when key is turned to ON, relay activates, and sends current to the electric fuel pump.



That is a standard SPDT 30amp relay, available any auto parts store, about $7.

85 = any hot-in-run 12v+ source (wire that gets 12v+ when key is ON) - 18ga is fine here
86 = ground
30 = 12v+ from battery source (can get at starter, power distribution center beside radiator, pos battery post, etc.) - use 12 gauge here
87a = not used
87 = wire out from relay to connect into fuel pump 12v+ wire - use 12gauge here too.

4) Fuel lines. There should be 3 fuel lines already hooked up, a feed line (3/8), a return line (5/16), and a evap canister line (another 5/16). Assuming they are, and connected into your factory fuel lines up to engine bay ... You need a Mallory 4309 fuel pressure regulator - feed line IN goes in one side, return line goes in bottom, feed line OUT comes out another side to your carb.

That all make sense? Now, you'll have to determine if the fuel lines are there and connected, find the wires for the fuel pump, etc. and make sure you still have what I'm assuming you do for that much of it to work.

The 4th gen dash swap - I suggest leaving it alone if it works, because I'm not familiar with wiring diferences with 4th gen dashes. I know some are complicated - 4th gens had BCM's (Body Control Modules) that were seperate computers for things like locks, radios, electric windows, gauges, etc. Much more complicated that the 3rd gen cars. If that's the case with yours, and it's already been done to function, then swapping out for the 1985 harness may make gauges and such inoperable. Thus my reasoning is "If it ain't broke, don't fix it" - we can always find a way to tie in release buttons, 3rd brake lights, power locks, etc. with what's there, rather than trying to swap it all out again and end up with none of the 4th gen dash working.

Hope I'm making sense. Let us know if any of this might or might not work because of what you have or don't have to work with, and we'll try to help you adapt to what you have to keep it simple as possible.

 

https://www.thirdgen.org/technical-articles

 

Trust me i want to keep it simple as it makes it the easiest situation for sure

1 - I guess i forgot to leave that piece of info in the beginning. the 4th gen harness ia there but he was swapping back to a 3rd gen dash again so the 3rd gen dah is there but the wiring is set up for a 4th gen along with everything else. I have no 4th gen stuff what so ever in the car besides the E-brake handel and wheel with bag.

2 - car has no drivetrain in it so im setting it up while the motor is being built

3 - The pump works as the car had it running when the previous owner has a LS1 in it ill just have to run the relay wire then???

4 - I have no fuel lines at all as he took them with the motor for some odd reason. EVAP canister line isnt there either as the canister on a LS1 tank is on top of it but I guess it doesnt hurt to hook it up. i never did in the past

It does make sence but I think i got alot of work to do now LOL

 

Im swapping to my old 85 harness as i know it worked when I pulled it. I will also be going braided line on the fuel lines and return line. I will be doing the wiring as soon as I get the 85 harness in. Havnt had much time to work on the car due to working so much and reno's on the home. I will keep you guys posted if I need any other questions answered

 

Use coated hard line for the long middle body section where straight runs can go, then braided on the ends.

 

Ok heres what I got on the car. I have a stock filter with a line from the tank and I assume the line coming off the T section is a return line??? As you can see in the 2nd pic is stops there I want to redo both lines form the filter to the regulator ( mallory 4309 ). Does anyone know what I will need besides 3/8 braided line and 5/16 braided line?? Connectors anything so I can make it a little easier on myself. Thanks