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AaronK

81 l28et swap into 73 240z wiring help!

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Hello, I'm currently trying to complete an 81 l28et (with stock electronics) swap into my 73 240z, and I have a few questions about the wiring. Before anyone refers me to the search bar, let me say that I have already gone through every wiring guide I could find, and as far as I have found, everything that needs to be in plugged is, and I have the right wires running to I think the right switched power sources; but all it does is crank. I tried to use this wiring guide (though for an 82-83 l28et swap) to figure out where to wire all of my switched power to, but the wire color combinations for the ignition switch in this picture don't match what I have on my 73 240z, so I'm kind of lost. 

 

site1081_zpsa190617c.jpg

 

My Ignition switch wires are B/W, B/R, W/R, B/Y, G/W and look like this

 

DSC01372_zpse71e19c7.jpg

 

I have the yellow wire coming from the 280zx turbo ignition harness plug going to the ignition switch. the two B/W wires (the one for the Ignitor and the one by the efi relay) hooked together going to a 12v source on my ignition switch, and my fuel pump switched power going to a switch wire in the fuse box.

 

DSC01370_zps3ecfc2c1.jpg

(the two B/W wires are in the left, the yellow wire from the 280zx turbo ignition harness plug is in the middle with the black tape on it near the top of the photo)

 

What are the correct wires should I hook these into at the ignition switch? I have the B/W wires going to the B/W and the yellow going to the B/W at the ignition switch, the fuel pump it going to a wire off the fuse box, but I think the problem is that while the car is cranking the power drops down from 12V to around 10 or 9 where I have all of these spliced in. Don't these wires need a steady 12V while cranking (both of the B/W, Yellow, and fuel pump switched)? Does anyone who has done this swap know where to wire these that has worked for them? I know that it is getting strong spark, and I can hear my fuel pumps running when I have the ignition on, but all it does it crank. I believe that the ecu is working, I know this because I hooked up the blue/red wire from the 280zx turbo fuel pump relay (which is controlled by the ecu) to the switched prong on my fuel pump relay and it shut them off after 5sec of priming. Could it be possible that my AFM, CAS, or TPS is bad? I have a 240sx 60mm TB/TPS swapped on, do I need to change any of the wiring for the tps or could that possibly be what it keeping it from starting? Is there a way to for sure test any of this without buying new parts? Could the 280zx turbo's neutral safety switch, possibly be what is stopping my car from starting? Do I need to hot wire it or something? And if so how? Does this resistor need to be plugged into anything? I so, what/where?

 

DSC01371_zpsc0ad003b.jpg

 

Thanks,

Aaron

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If you have spark, that means the ECU is at least on and it's getting an RPM signal from the CAS. If your fuel pump is running as you say and you have fuel pressure, are your injectors firing?

 

Do you have the injector dropping resistors from the 81 harness plugged in? It's a large metal block plugged in just outside past the firewall grommet.

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The Black/Yellow from the IGN switch is the start signal (tells the starter to turn and crank the engine).   Is that the "Yellow" you're referring to?  The "start signal" to the ECU?  If so, it should NOT be connected to the Black/White.  The Black/White is the IGN ON signal and it provides power (+12V) to the Ignitor (and from the Ignitor to the coil) and to the EFI Relay.  That's in the wiring diagram above.  (and, there's a connection to "plug 3" which also powers the air bypass valve and the CAS IIRC - but that's in the turbo circuit diagram in the Factory Service Manual - your best friend...)

 

If you have a 1981 ECCS (engine, EFI) harness you need the dropping resistor pack plugged in.  If you don't the injectors have NO power.  Easy to check voltage at the injectors.

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Well, thanks for the input guys. I got it started today, I found that I actually had everything hooked up right, but I had my feed and return lines going from my surge tank into the stock turbo fuel rail mixed up... :icon56: Anyway, the car idles nice, but dies when I try to rev it, which I believe is due to extensive vacuum leaks (various things not hooked up) and not having the intercooler plumbed yet.  

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