I've read EFI Bible...studied schematics... help please.

[EverRude]

I've got no power to the fuel pump. Nothin in the "start" or "on" (with AFR opened) positions. I jumped the pump to a 12 volt source and it works.

 

Now before we get into the troubleshooting stuff with the air temp sensor or thermodyne or tempeture sensor..etc. Please keep in mind this car has been setting a long time but not before it's electrical system was hacked for whatever reason. A modern stereo was installed that doesn't have power. Lots of splices in the steering column and under dash. Several strange things under the hood. Heck, every single guage bulb socket was removed the the guages and are just hanging loose behind the cluster. No instruments work when key is switched on. It's a mess.

 

But the stuff that currently worries me is the disconnected wiring. I took pictures of several wires that are just loose. The 2 that stump me the most are at the ECU connector and I'm wondering if they are my fuel problem. I just don't know where any of these wires hook up. I can't find what they are supposed to connect too.

 

So please if you know, post. I think my eyes are bleeding trying to find these wires on schematics.

 

See the 2 white wires with female bullet connectors. They coming from the ECU plug. Where do they connect? Or did someone mod the harness for something?

 

This shows the passenger side fusible links. Below there is a burned out ground wire and 2 unconnected wires. No idea where they connected before. I'll take a better picture of those later. Just realized they didn't really show well in the mess.

 

The 2 wires come from a 4 wire bundle leading to a junction block below the coil. Shouldn't the be hooked up to something? The are solid red and solid green.

 

This shows a wire coming from the ballast mounted above the coil. Again what was it connected too?

 

Thanks in advanced. I know if I looked harder I might find some of this stuff in some harness schematic. I've looked at the body, EFI, engine harness, and dash schematics. I'm sure they are there somewhere .... I'll keep looking.

[SkunkTeeth]

The two white unconnected wires at the ecu are correct. I saw that on mine and checked in the FSM. I believe the red and green wires go to the egr solenoid?

[zpizzaman20]

In the second picture there should another fusible link box.

[EverRude]

Well if those are the EGR solenoid wires it explains why they are disconnected. Notice below my hand in that picture the EGR valve has been removed and a block-off plate installed.

 

Anyone happen to have a picture of the second fusible link box I should have?

[naviathan]

The "ballast" above the coil is just a ground capacitor to clean some of the noise out of the electrical system. The red and green have me stumped a bit so they must not be too important, but it looks like you're missing a fusible link box, there should be two side by side just like the one you have. Where did you get this car??? Looks like it came out of a junkyard with all that rust and mess. What year is this?

[EverRude]

Yeah it's been sitting in a field for awhile. Not sure how long. Not sure I'd trust the previous owner telling me had I asked. It's a 1975 280z. It had a ton of wasp nests and most of the rust is surface. Only a few holes

 

Thanks for the responses so far guys. Seems no magic bullet for the fuel problem unless that missing fusible link box is the issue. Possibly removed? Would the 81 280 ZX Turbo I got with this car have that part I could steal?

 

It's raining now so I'll get more pictures posted after. Maybe something else will be it. Meanwhile I'll be going out to replace my multimeter. Darn thing won't work in continuity mode.

 

BTW the Nissan L6 forums has exterior pictures of this car and the ZX Turbo I got with it. No sure about the rules about posting a link to another forum here so I won't. Just letting you know it exists if you curious what this car looks like aside from the wiring.

[EverRude]

Figured out the wires I mentioned below the fusible link box. The alternator. It's not installed. Don't know how I didn't notice. Is the alt on the 81 280zx the same as the 75 280z?

[EverRude]

Finally found the red and green wires on the schematic. Helped having a component to look for rather than just random wire colors. EGR solenoid. THanks

 

Only seeing one fusible link in engine area of the 1975 wiring schematic. I may be missing it.

[dhp123166]

Dude,

I would find out where that connets to because I had that same thing in my '76 280z. I didn't think I needed it and I took it out.

 

Lo and behold the car would not start.

 

I put it back in and it started.

 

Someone told me it was some kind of starter resistor or something.

 

Of course I could be wrong...

[dhp123166]

The wire that connects to should be in the same wire bundle as where the wire going out of the resistor reenters the bundle, only slightly behind it (towards the ECU)...I guess look for a single black wire, maybe the terminal fell off or something...

[EverRude]

Pic 4 shows the condensor according to the schematic. The disconnected wire is supposed to go to ground. The ZX has the same thing and it grounds to the block at the water neck.

 

I'm sure that's what Naviathan meant I just didn't catch on.

[Daeron]

only one pair of fusible links in the 75.

 

Hit blue's techtips page for a good, HUGE, one page .pdf wiring diagram for the 75.. its one page, and it doesn't have the gaps that the four page PDF has in it. http://www.atlanticz.ca/zclub/techtips/electrical.htm

 

The fuel pump circuit is completed by a switch in the AFM, and a master "Fuel Injection Relay" that is actually two small cubic relays just above and aft of the ECU, slightly towards the center of the car, underneath the dashboard.. and reading the explanations and diagrams in the EFI bible will yield much more tangible explanations of how it works than reading the raw chassis wiring diagram. The bible tells you "how," and the wiring diagram is just an abstraction of "where" and "what."

 

What I would recommend would be to get the one bigass .pdf wiring diagram, and "copy" it to your clipboard, and paste it into a .bmp in paintbrush. Then you can use a series of colored dots to trace out each wire, and it makes reading the schematic a ton easier. Just remember never to save unless you can keep track of which dots are which. Rather, I keep notes on where each wire goes so I can simply flip over to the relevant connector and see "okay its that WR wire."

 

 

The alternators are NOT the same between 75 and 81; the 75 is externally regulated and the 81 is internally regulated. There is an easy to execute swap to eliminate the external regulator and use the ZX alternator, but I would get the car running properly first.

 

Regarding the entire fuel pump issue.. For the time being, to try to get the car to run, it is an acceptable option to run a hotwire to the fuel pump. The entire five years I DD'd my 75 was before I had discovered any of the FSM and EFI bible goodness, and the whole TIME my fuel pump was hotwired; in the end, it proved to be a bad idea to run it so long like that, but I won't go into that here. Anyhow, if you want to do that to get her to fire for encouragement (and possibly to appease any people you might live with who are glaring at you over buying two dead cars ) it isnt that bad an idea. Once you know it will work, you can take the time to read through the theory section of the bible, and construct an accurate mental image of how the fuel pump is supplied with power.

 

From there, it depends on your luck. I have burnt wiring now; I don't want to talk about my issues on your thread, but the fuel pump power wire (that green one that has been hurting your eyes so badly, running through connector.. ahh, C1 or 2 is it? I can't recall off the top of my head right now, its the big black one up in the top inside corner) is a long, intricate, and evil mother to be dealing with. Mine is totally burnt, and I will need to pull the dash and get into the rocker panel wire loom and replace the whole thing, as well as any other wiring damaged by the heat. So, physically, that wire runs up from the fuse panel, to a bridge where it shoots across the dash to the ECU/relay. I can't recall how the AFM is involved but i believe that was just a signal wire going to the relay. The wire gets bridged at the main junction block again, and shoots back along the passenger rocker panel in the main loom going back towards the tail lights. It's basically like, ALL of the body wiring that that PARTICULAR wire is in the midst of, so it is a fun one.. but chances are your issue will be solved easier than mine.

 

Good luck; I have my 75's wiring all torn apart at the moment, but the majority of it is still connected where it is supposed to be, so fire any model specific questions my way. I am all stock still, BTW. What is your manufacture date? its on the door panel, mine was may '75. Not sure if disparate production dates within the 75 model year would show up, but if we are close then we can be rather confident that our cars should match. May 1975, federal emissions, 4 speed manual car, with AC. (yours looks to be AC, and IIRC it was federal 4 spd.)

 

Hope this helps, and if not.. well, ask me more questions! I should be able to answer most anything about the car for you.

[zpizzaman20]

Sorry about the fusible link distractor, you did not say what year and I am so used to 77-78's.

[EverRude]

zpizzaman: It's cool bro. My fault for not specifying the car year.

 

Daeron: You're awesome. I appreciate all that info. I may just hotwire it after I get more fuel in the tank. Only about 2.5 gallons in there now. I don't wanna risk overheating it unprimed and with too little gas.

 

Now that I'm awake I"ll be getting the new multimeter. I wanna see if I can figure out the pump issue correctly. But it will be getting fuel before the day is out.

 

Thanks

[EverRude]

Quick alternator question. Since my alternator is gone and some of the wiring is hacked I need to know what I need. Here's a pic from AtlanticZ for the alternator swap guide. It shows are condensor mounted to the ground "E" connector. Is it required to run? Or can I skip it till I find a local salavage with these cars?

 

[dhp123166]

A fuel injected Z with no alternator will not run.

 

At least mine did not.

 

What happened was, I upgraded to an '86 Maxima internal voltage regulator model that cranked out 90 amps.

 

It was also a single wire app. I ran the power wire through the fusible link

like stock but kept frying links.

 

I ran it directly but it would not start.

 

One of the wires in the fusible link ( I forget which one, white with red stripe) signals the EFI or something.

 

I spliced it in to the four gauge power wire I am now using and it works fine...

[dhp123166]

The thing I learned about EFI management in my Z is that it is a closed system.

 

All components have to be there for it to work.

[EverRude]

Ok so your saying I should get the alt replaced. But would this affect my fuel pump not coming on? It doesn't matter if the injectors are firing or not with no fuel to them.

 

Also doing the troubleshooting using the EFI bible with the "No fuel pump" guide I get power and continuity everywhere it says. Next step? Replace ECU. That aint happening till I sort out the wiring.

 

There's also another issue. The clutch is stuck engaged. I got no pedal. But the slave has the clutch fork maxed out. Either the slave is rusted open or the clutch has siezed to the flexplate. I know there's an interlock that forces you to depress the clutch to start the car. But would that prevent the pump from getting power?

 

Oh and I have been trying to get the pump primed. I have about 6 gallons in it now. And I used an airhose to slightly pressurize the tank. Used a spare battery to power the pump and it works. But no fuel is reaching the fuel filter at the engine. I removed the hose to the pump and it definitely has fuel going to it. I guess I could disconnect the surge valve and see if fuel is coming out of it.

 

Still whether the pump is actually sending fuel or not it isn't getting power. I'm troubleshooting 3 different things at once and all interelated. I want to go step by step and stick to one system. So I think I'll concentrate and being sure the pump is sending fuel forward. Then sort out why it gets no power.

 

This is fun

[dhp123166]

No alternator would keep the system from functioning as a whole. ( I believe).

 

All things have to be working in order for the ECU to send power to the fuel pump.

 

My experience is that one cannot just get one thing to work in this system independently of another.

 

Conversely, if one thing is malfunctioning, the whole system will not function.

 

They all have to be functioning in order for the system to work...

[EverRude]

OK...one step forward two steps back.

 

I primed the full system finally. Full is pumping through the fuel filter and into a container. So I hooked it back up.

 

Decided to see if I could start the car with the pump hot wired to a separate battery and running. Engine won't turn over. Dang. I check power. Battery is a little low but should still turn over. Disconnected my hotwire to the pump and reconnected the harness to it. Try the key. Pump starts! Wow. Still the engine isn't turning over. Dang!

 

So close...

 

Gonna let the battery charge awhile and do some searching about the engine not even attempting to turn over. Just a click of the relay and nothing else.