coptzer

iTrader: (2)

I've installed the 2002 LS1 tank and Racetronix pump with hotwire kit. I need to splice the wires from the tank connector to the 3rd gen bulkhead. What needs to be done to retain the factory 3rd gen 3 wire bulkhead?

Can't seem to find a good answer. I've seen people use the car side 4th gen bulkhead, but I don't want to if I don't need to. I know there are 4 wires to retain, but how does it get spliced? Blk, Blk/wht, Ppl, Gry... right?

Any help would be appreciated as I am trying to get this done today so I can finally install my new rear.

Thanks.

QwkTrip

iTrader: (22)

The connector behind rear seat has three pins. One is fuel sender source, the other two are fuel pump positive and ground. You're going to change the purpose of those wires. There is no fuel sender ground because the fuel sender is grounded to the metal fuel tank, but 4th gen tank is plastic so you will need to deal with that in the new setup.

1. The old fuel pump positive will now control the Racetronix relay. If you follow the wire all the way to the front of the car you'll find that it goes to the fuel pump relay on the firewall in the engine bay. Ditch the old relay. Run the wire to the engine PCM terminal R9 instead. Now the PCM can control the fuel pump, just like a 4th gen car.

2. Run the original fuel sender "source" wire to the 4th gen fuel sender. Done.

3. Run the 4th gen fuel sender "ground" wire to the old 3rd gen fuel pump ground connection behind the rear seat. If you trace that wire inside the car you'll find it is grounded to the floor pan. This will serve as a good ground for the fuel sender. The sender inside the fuel tank is just a resistor so it doesn't matter which wire you grab for source or ground. It will work the same either way.

4. Keep in mind that the 4th gen fuel sender has a different resistor then the 3rd gen sender, so your fuel gauge won't display correct. You'll either need to swap out for a different sender inside the tank, or change the resistor in the back of your fuel gauge.

coptzer

iTrader: (2)

Sounds easy enough, thanks for the great explanation. I think I am over-thinking it making it harder than it needs. The problem is I started my wiring about a month ago then got sidetracked. Now I'm in the middle of a T56 rebuild... So I keep going back and forth from one to the other. Probably not the best way to do this swap. Anyways, I am planning on grounding the fuel pump to the chassis, either the old sender ground or on the outside. I'd like to have one inside and outside. I already have my hotwire kit grounded to the outside right next to the bulkhead. I've also already replaced the sender in the tank to the 0-90 ohm one.



I have traced out the brown and Pink wires that run to the front of the car, and I have my interior out so this makes everything easy. It looks like these these two colors go into the bundle right behind the C100. At least I think that's what it is. Not sure which wire goes to what, but I'm sure it doesn't matter as they will be repurposed. So can I just cut whichever one will go to the computer and run it along the inside to the computer? One must already go to the gauge right?

Thanks

QwkTrip

iTrader: (22)

That's pretty slick how you made that pass through for the wire. Is that a rivet?

Change the stack on that ground bolt. Put the wire ring terminal on the bare sheet metal because that is your ground contact. Put the fuse holder on top of ring terminal. Also, it wouldn't hurt to make sure the bolt and nut has a conductive coating as well. Look for zinc plate (not zinc flake), stainless, or other conductive materials. Welding a stainless stud to the sheet metal is ideal. Zinc plate and stainless will last a long time without corroding.

Yes, the old fuel pump B+ comes from the engine bay through C100. I would check both sides of C100 and make sure it is a single wire on both sides. If so, then you can cut the wire anywhere. If for some reason there is a 2-wire split, then you need to consider what is the other circuit because PCM R9 doesn't have capacity to run anything except the Racetronix fuel pump relay. Also remember to kill power in the old fuel pump circuits, or remove the wires, so you don't have voltage on unused wires and risk of shorts and harness fire.

I've never seen anybody do it this way except you and me. It sure makes a clean install and you managed to not even run any wires under the car!

coptzer

iTrader: (2)

Thanks again for the info, I will trace the inside wire out further this weekend. The sucky part is it is taped in a huge bundle of wires.

That's a small grommet I found that the power wire passes through. I have a drawer in my tool box with nothing but old spare nuts, bolts, and random parts. I happened to find that grommet and fits the wire and loom perfectly and locks to the chassis nice and tight. I did not want to run any wiring underneath if I didn't have to. Like you, I am pretty particular about how I am doing this and how I want my car to look. Which is why this swap is taking so long...

I believe I hooked the ring terminal to the chassis first with a star washer under it and stacked the relay on top of it. I will have to double check now. It's all on a through bolt from the inside, but while it's still apart I think I'm going to weld it to the chassis instead of relying on the nut and bolt. Now looking at it again, I probably should have scraped the inside a little better. Here's a look from the inside...

QwkTrip

iTrader: (22)

Don't use a star washer. It just reduces surface area of contact and gives an air gap for moisture to collect and corroosion.

camarozz383

iTrader: (2)

can you tell me what color wires got to the hot wire kit, what are the pink, brown and black? black is ground im sure? my pump wont turn on when i turn the key, :{

coptzer

iTrader: (2)

I haven't actually hooked mine up yet, but it shouldn't be that hard. I think it was Qwktrip that had a good diagram of it. Black is ground, for the pink and brown- one is the gauge and one is the old 12v +. You need to have the PCM to trigger the relay so reuse the old power wire to do this and splice it to the correct wire from the 4th gen connector. If I remember right it needs to get spliced to pin Red 9 of the PCM (verify this before you do it). I traced my old wiring to the C207 but can't remember what is what. I have the 3rd gen and the 4th gen connector wiring all written down somewhere. I should be doing mine this weekend. Hope this helps a little.

JCS94

iTrader: (1)

hey coptzer/QwkTrip, sorry to revive this thread, but in short, you took the power wire from the fuel pump sender and plugged it into the wire that runs from the fuel pump relay wherever it is mounted (mine will be under the passenger side dash along with my 411 PCM) and then you just grounded the other wire? And I already have planned out how I am going to be running the custom fuel level sender.

QwkTrip

iTrader: (22)

Yes, if you have the LS1 Racetronix Hot Wire kit then the larger 10 gauge RED wire goes to fuel pump. The smaller BLACK wire gets grounded somewhere of your choosing. There is a redundant ground in the Racetronix harness so that can confuse people.

The LS1 Hot Wire kit is made to be plug-'n-play with a 4th gen car, so it ends up having extra runs of wiring and connectors when placed in our cars. The following link shows you how the Racetronix harness is constructed (ignore the rest of the diagram)

https://www.thirdgen.org/forums/ltx-...ml#post5151055

It is very easy to eliminate some of the extra wiring from the Hot Wire kit. It doesn't look like much of a change when comparing wiring diagrams, but it did eliminate the mess of wiring at fuel tank.

https://www.thirdgen.org/forums/ltx-...ml#post5893401
https://www.thirdgen.org/forums/ltx-...ml#post5893412

My final iteration is not shown here. I ended up dismantling the kit and pretty much just used the wires as core material to make my own harness. Fuse and relay is integral to an underhood fuse/relay center I installed. The only thing you see at my fuel tank is a bundle of wire that goes inside the car.

JCS94

iTrader: (1)

Awesome thanks for the useful information, QwkTrip! I Just noticed you were from Illinois as well! I'm at SIU for college.