Wiring Confusion

[Guest tony78_280z]

I've checked the archieves and they have been most helpful but I've stumbled upon a few questions that are probably quite simple to someone who has already performed this swap.

 

#1 Altenator

Someone said on a post somewhere that "Wire 8: The Blue wire that went to the Z voltage regulator now goes to the plug in on chevy alt. to the left terminal as looking at the back of the alt."

 

Well lets say that somebody must have got snip happy and cut this wire off way back and has no clue as to where it is. Or that his 280z had an internal voltage regulator and this wire never existed. Either way, where exactly would I run the wire that would be plugged into the left terminal as looking at the back of the alt.? Simply to the Ignitiona switch?

 

#2 Distribution and Coil

The same guy whom I'm sure is quite helpful but kind of confusing said that " Wire 1: The Black/Blue wire that went to the Z coil will now splice into wire 2. Wire 2: The Green/Blue wire from the fuel pump now connects to the Chrysler Fuel Pump Switch. A wire on the other side of chrysler switch splices into wire 5. Wire 4: The Blue wire that went to the Ignition Relay in the passenger footwell (Ign. relay discarded) now has a 15K ohm resistor in line to the neg. side on the HEI Dist. Wire 5: The Black/White wire that went to the Ignition Relay in the passenger footwell now goes to the plus side on the HEI Dist., it also has a wire from the plus side of the Chrysler Fuel Pump Switch spliced in (see wire 2)"

 

So the picture I've drawin from that is simply...

Black/Blue (that would goto the Z coil, but now) goes into a Chrysler Fuel Pump Switch (what is that). The wire then goes to the HEI Dist AND to the Fuel Pump (turning them both on at the same time) The wire (Blue) leaves the HEI Dist the goes into a 15k Ohm resistare and then to ground.

 

Well... I don't have an HEI Ground wire that I can see anywhere. I thought it simply grounded into the motor. Where would a guy get a 15k Ohm Resister. Where would I get a Chyrsler Fule Pump Switch? (From what model Chrysler could I find it, and what does it look like?) I must be right as the car does run. The set up I have now is rigged up to run. But it's not clean or pro like.

 

280z into a Carbed 350 is more complicated than I thought it would be in the electrical area.

 

Thanks in advance for any help.

[GAZRNR]

I am running a carberated 350 in a 78 Z and the wiring was not as hard as I thought it would be once I got started. I removed the harness from the car because it was easier to work with and got rid of the FI relays not used. I looked for my notes on wiring but could not find them so I will go from memoray. Do you have the JTR book? If not then get one.

 

1) Alt - the blue wire gets wired into the large white with red stripe that goes thru the fusable links to the battery. You will need the correct pulg for the GM alt you are using and this is an easy swap.

 

2) the black with yellow stripe goes to your starter "S" clip.

 

3) I used the black with white stripe to get power to my pos on my MSD box and get power to my fuel pump.

 

I can't help you on the ground for your distributor but you should trace it back to where it was snipped. I also would not worry about the low oil pressure fuel pump cut off switch at this point. Get it running then wire in you accessories.

 

Hope this helps,

 

Rusty

[dr_hunt]

Don't put a resistor anywhere in any wire on an HEI, they require a full 12-14 volts! The negative post on the HEI terminal cap is for the tachometer, not ground. Personally I wouldn't wire the ignition and fuel pump in the same circuit for fear of voltage drop to the internal coil of the HEI. Separate circuits are also easier to troubleshoot as well.

 

Don't know diddly about z wiring, can't help with anything more.

 

David

[awd92gsx]

Tony,

 

Did you ever figure this out?

 

I was going over the wiring tonight while at the Emergency Room (long story, involving stepson and kidney stones) and the manual is uber-vague about the whole fuel pump wiring. For the most part I have it figured out, but, where is the easiest place to splice into the fuel pump wiring? Do I need to run a new wire all the way back end of the car?

 

The JTR is good, but, it's not very specific about the things that really make a difference.

 

Maybe somebody needs to come out with an Idiot's Guide to V8 Z Swapping that doesn't leave so much up to the imagination or assumption.

[Georgia Flash]

I too am at this place on my project. Me and my garage buddy (wife) spent the morning separating and hacking wires in the engine bay. We think that we have everything figured out except the fuel pump wiring.

 

Bill you hit the nail on the head as for the JTR book being a little vague on the wiring issue. I have managed to find the green/blue wire (280Z) that it speaks of and have traced it from the fuel pump, where it starts out solid green, underneath the passenger seat to the cluster of wires going under the dash.

 

My question on this issue is where do I splice into this wire. Does it matter? If I am not mistaken, the green/blue wire goes all the way to the Datsun ignition switch. Do I disconnect it there?

 

I have discarded a lot of the original Datsun wiring and I am down to what the JTR manual says, “you only have about ten wires that go to your engine.â€

 

Any help on this would be appreciated. I will keep searching, but this thread is the closest thing that I have found to answer my question so far.

[Dudeboy]

GeorgiaFlash75V8,

 

You may have this already, but Autozone has a 1975 Z diagram. I have the color 1977 diagram on PDF, but the black and white diagram on Autozones site is clearer.

 

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1d/1d/80/0900823d801d1d80.jsp

 

I am following your post as well, my buddies close by who have made the swap have 240's - the 280 is a different animal.

[Georgia Flash]

Yeah I have the factory service manual but that will not answer my question. Where do you cut the wire to the fuel pump? I re read the JTR manual on the fuel pump wiring and it confused me more. According to the manual you should look for a black-white wire in the passenger foot well area not the green-blue wire...oh brother here we go again.

 

I have spliced/cut the green-blue wire before the relay and plan to run that to the Chrysler fuel switch tonight or tomorrow depending on when I get my engine together. I have to put on the heads and related items and I will be ready to put the engine and tranny together and bolt them into my car.

 

I will keep updating this old thread especially when I hook up the juice to see what happens.

 

If I am successful with my wiring, I will make all 280Z owners the following promises:

 

1. I will never ignore another member’s plea for help on an item such as this.

 

2. I will never just suggest, "Buy a FSM" when I know the answer already.

 

3. If I do not know the answer I sure as hell will not just suggest buy a FSM!

 

4. I would be willing to drive (reasonable distance) to a fellow member's home to help him or her with the wiring issues.

 

I am going back out into the summer heat today and knock this baby out! Wish me luck.

[Here comes trouble]

Go for it , Charlie !!!!!!!!

[awd92gsx]

I went an entirely different route than the JTR manual.

 

I used a relay and a diode to operate the fuel pump system. I also ran a dedicated wire directly to the fuel pump for maximum voltage to the pump and the least amount of voltage draw from the HEI system.

 

It worked out quite nice and is very easy to install due to it's simplicity...even easier, imho, than the JTR method.

 

If anybody is interested I can find the schematic I drew up for it. I feel it's a superior alternative to the JTR method (that relies on 25+ year old wiring), but, everybody has their own opinions.

[Georgia Flash]

Sure send it my way.

[Guest Nikolai]

I too like the idea of wiring everything independantly with new wire. With my 4.3 install, I'm going to use the fuse box out of the truck I got it from and wire that up. Should make for a nice clean and reliable setup.

[awd92gsx]

OK...here's the schematic. I had to redraw it, but, you should get the basic idea.

 

 

Doing it this way ensures full voltage reaches the fuel pump, while being very very simple to install.

[Georgia Flash]

Thanks I will have to think about doing it this way. It seems a little less complicated.

[awd92gsx]

All of the wiring is done in the engine bay, except that you'll want to run a new wire to the fuel pump. I placed the relay setup down by the battery, near the starter solenoid to keep the wiring length at a minimum. I had some spare 10 guage amp wire that I wasn't using anymore so it ended up working out pretty good.

 

Voltage drop across the entire circuit *should* be almost nil (less than .1v)