Fuel Pump Wiring

[greenz28]

I'm converting to a carb setup and need help finding the power wire for the fuel pump to wire it to a switch or keyed ignition. Can someone tell me which wire it is? I found the diagram for the fans on shbox website, but can't seem to find anything for the fuel pump.

[greenz28]

I was able to find this pic for the fuel pump relay location, but still need to know which wire powers the relay/pump.

http://shbox.com/1/fuel_pump_relay.jpg

[greenz28]

I was able to find this pic for the fuel pump relay location, but still need to know which wire powers the relay/pump.

http://shbox.com/1/fuel_pump_relay.jpg

Ok, I think I found what I was looking for in post #19. I'll leave this thread here for updates incase anyone else needs it.

https://ls1tech.com/forums/conversions-hybrids/1712619-lt1-ls1-swap-no-start.html

[harner]

Looks like you found your answer. I was probing all of these wires to troubleshoot a failed Racetronix pump on my car just a few weeks ago. The gray wire in the back of the car, relay, connector under the dash, etc. I ended up buying a new pump and it magically started working. Imagine that.

[Injuneer]

Fuel pump relay gets 12 volt control sIgnal from PCM. If you are deleting the PCM you need to supply 12 volt switched power to terminal 85 of the relay. Shoebox PCM diagram:

http://shbox.com/1/1995_pcm3.jpg

[greenz28]

Perfect, thanks!

[greenz28]

Looks like you found your answer. I was probing all of these wires to troubleshoot a failed Racetronix pump on my car just a few weeks ago. The gray wire in the back of the car, relay, connector under the dash, etc. I ended up buying a new pump and it magically started working. Imagine that.

So, it started working before or after the new fuel pump install?

[harner]

So, it started working before or after the new fuel pump install?

New fuel pump and it started working.

My car is an LS swap with a custom plug and play BP Automotive harness that has been sitting around for years. So when there was no pump with key on and not being able to force it to prime with HP Tuners, I had to probe the harness. Started with the prime connector by the PCM under the hood, then the connector under the dash on the PS, relay, and started probing the gray wires in the Racetronix hotwire harness. I even probed the pump itself after ripping it out of the tank. $150 later, a new pump fixed it, but all of the testing was necessary due to all of the aftermarket components. Not too relevant to this thread, but feel free to check out my build thread (http://www.ltxtech.com/forums/showthread.php?28190-Project-1994-Trans-Am)if you're interested.

[Injuneer]

What year is your chassis? The 93-95 uses the wiring diagram shown in the Shoebox schematic, with a 4 terminal relay. The 96/97 uses a 5 terminal relay and the wiring is slightly different, due to the prime connector wiring passing through the relay, instead of bypassing it. In both cases, the 12 volt switched power goes to terminal 85.

[greenz28]

What year is your chassis? The 93-95 uses the wiring diagram shown in the Shoebox schematic, with a 4 terminal relay. The 96/97 uses a 5 terminal relay and the wiring is slightly different, due to the prime connector wiring passing through the relay, instead of bypassing it. In both cases, the 12 volt switched power goes to terminal 85.

It's a 94.

Another question while I have your attention: For the starter solenoid, can I use the factory wire and just bypass the security relay behind the glove box? Also, I assume the Shoe Box manual fan switch diagram will work for me if I use the pcm controller wires and tap them into a keyed 12 volt source? Thanks again!

[greenz28]

New fuel pump and it started working.

My car is an LS swap with a custom plug and play BP Automotive harness that has been sitting around for years. So when there was no pump with key on and not being able to force it to prime with HP Tuners, I had to probe the harness. Started with the prime connector by the PCM under the hood, then the connector under the dash on the PS, relay, and started probing the gray wires in the Racetronix hotwire harness. I even probed the pump itself after ripping it out of the tank. $150 later, a new pump fixed it, but all of the testing was necessary due to all of the aftermarket components. Not too relevant to this thread, but feel free to check out my build thread (http://www.ltxtech.com/forums/showthread.php?28190-Project-1994-Trans-Am)if you're interested.

I love the build thread. I'm actually doing an LS swap also, just going to a carburetor and powerglide since my plan for the car is 90% track now. We swapped my old LT1/4L60e into another 94 z28 for my dad. We are finally getting all the little bugs worked out of it, so I finally have time to focus on my build. I should've made a build thread for mine. It is getting a complete makeover with body work, new paint and new motor/trans.

[greenz28]

3985139850

This is where I am right now. So much work ahead of me! Breaks my heart seeing the old girl like this.

One day soon I'm going to take a day to clean my shop, sorry for the mess, haha.

[Injuneer]

It's a 94.

Another question while I have your attention: For the starter solenoid, can I use the factory wire and just bypass the security relay behind the glove box?

http://shbox.com/1/starter_charging_95.jpg

Just pull the connector off the theft deterrent relay, connect the yellow wire to the purple wire. The theft deterrent relay and the hatch release relay are all the way to the right, right side of airbag/glove box support. Don't confuse it with the theft deterrent module, which is between the radio and the left side air bag bracket.


Also, I assume the Shoe Box manual fan switch diagram will work for me if I use the pcm controller wires and tap them into a keyed 12 volt source? Thanks again!


You may want to determine if you have an "early 94" model year wiring setup (2 relays, fan #1 on/off; fan #2 on/off), or the "late 94" model year wiring (3 relays, Both fans on low/off; both fans on high/off). In either case, the dark green wire is the lower temp response and the dark blue wire is the higher temp response. Will this be a manual switch, or will you incorporate temperature sensor/switch control?

http://shbox.com/1/1995_pcm6.jpg

[greenz28]

Just a manual switch, or on all the time with the key on.

[harner]

There is a BP Auto swap harness for sale in the classifieds if you want to keep your electronics in tact and stay fuel injected. Just saying lol. Regardless, should be a fun project. Good luck.

[greenz28]

I know i know, lol. I went back and forth for a long time before making the decision. I hope I don’t regret the carb, but I’ve already bought it and everything to support it.

[greenz28]

http://shbox.com/1/starter_charging_95.jpg

Just pull the connector off the theft deterrent relay, connect the yellow wire to the purple wire. The theft deterrent relay and the hatch release relay are all the way to the right, right side of airbag/glove box support. Don't confuse it with the theft deterrent module, which is between the radio and the left side air bag bracket.




You may want to determine if you have an "early 94" model year wiring setup (2 relays, fan #1 on/off; fan #2 on/off), or the "late 94" model year wiring (3 relays, Both fans on low/off; both fans on high/off). In either case, the dark green wire is the lower temp response and the dark blue wire is the higher temp response. Will this be a manual switch, or will you incorporate temperature sensor/switch control?

http://shbox.com/1/1995_pcm6.jpg

I think I have 2 fan relays, but I will double check. What you’re saying is that either way the wiring is the same for a manual switch?

[Injuneer]

Yes.

I would recommend using a simple thermostatic switch so the only run when needed.

[greenz28]

Yes.

I would recommend using a simple thermostatic switch so the only run when needed.

I could wire the pcm control wires to a keyed 12 volt and use something like this on the ground side of the relay, correct? That, or ground the fans directly to the switch?

https://www.summitracing.com/parts/sum-890117

I think I have a tapped hole in each head for temperature, so I could run this switch in 1 head and the gauge sender in the other.

[Injuneer]

With the factory wiring, the control side of the relay is wired directly to a fuse (#6 under hood box) supplying ignition switched 12 volts.

The PCM wire provides the ground to the control side of the relay.

Connect the dark blue and dark green wires together, and run them to the thermo switch you linked. That switch activates the control side of all the relays by grounding the PCM wires to the head as a ground.

In the early wiring diagram both fans will turn on at 185°. On the late wiring diagram both fans will turn on at high speed at 185°.

[greenz28]

Well that’s simple enough. Thanks for being patient with me and answering all my questions.

[greenz28]

Thanks again for the wiring help! I started the new motor on Monday. Still a lot of work to do, but it was great finally getting to hear it run. It sounds like its going to be a runner!