Was trying to fix cold start injector and now not fuel pump operation...what happened

[RPM Resto & Custom]

Car is a 75 280Z with an XR3000 ignition setup.

Ok so I've been trying to track down a cold start injector that wasn't working and now somehow over the weekend the fuel pump has stopped operating.

I've tested the fuel injection relay as per the FSM as well as the cold start valve itself and the thermo time switch.

Not sure how but it looks like I'm not getting 12V from the ignition switch down to the fuel injection relay now. There is 12V exiting the switch on all of the proper terminals in the Start and Run positions. After looking through some wiring diagrams it looks like at least in the Start position I should have 12v coming from the black/yellow wire at the switch and it makes it's way down to a 4 wire connector that has 2 green and 2 white wires on one side and the other has yellow, red/white, and 2 others. If I read the wiring diagram right the 12V from the ignition switch should be coming down to this yellow wire and feeding the fuel injection relay. Both the black/yellow wire from the switch and the yellow wire from this connector go up under the dash too far for me to find where they would pair up. Am I correct that these wires should attach?

If I jumper 12V right from the switch to the 4 wire connector where the yellow wire terminates the fuel pump runs so I know the pump is ok. Plus it's only a week old. There is no other relay for the fuel pump that I may have blown is there?

[RPM Resto & Custom]

Little update. I got the fuel pump pumping again but I'm not sure the logic behind how. It seems the cold start injector has to be grounded to the intake in order for the fuel pump to run. Also the pump won't run with the small wire off of the starter solenoid and the ignition in the Start position still which I believe it should do.

So with the cost start valve grounded the engine runs now. However the valve still isn't operating properly. If I prime the fuel system and jumper the csv off of the battery it sprays fuel so the valve itself is ok. The thermotime switch is brand new as I suspected that to be my original problem after my ohmeter readings didn't match what the FSM specifies.

I ran the diagnostic outlined in the FSM for the thermo time and FSV that involves jumping both sides of the thermotime connector and testing pin 21 on the injection controller harness while cranking. I don't get a steady 12V...it seems to come and go and I can hear the relay clicking. Is that all I'm supposed to have or should it be constant?

Also if I plug a fuel injector noid light into the harness for the csv I get no signal. However maybe that's because my injector needs to be grounded for some odd reason?

[RPM Resto & Custom]

Alright I've just about got this narrowed down but I'm stuck at this point.

It looks like I'm on the right track with not getting 12V from the ignition switch black/yellow wire down to the yellow wire in the 4 wire connector that eventually feeds the fuel injection relay. I ran a jumper directly from the 12V Start position on the ignition switch down to the yellow wire on the 4 wire connector and the cold start injector works perfectly when you crank the car over.

So where am I losing my 12V signal between the ignition switch and that 4 wire connector?? I followed the wires up under the dash as high as I could but they go above the heavy bracketry that the pedals attach to and behind the speedo/tach area.

[Zed Head]

I see here that you have a 75. New info, not in the other post.

The fuel pump should run when the key is at Start and the small wire off the starter solenoid. If not, you have other stuff going on. Looks like a messy situation.

You're creating chaos by creating new posts on the same topic, but I guess that fits your situation overall. Good luck.

[RPM Resto & Custom]

Zed....I'm keeping all future posts in the other thread. I tried starting this one to weed out all of the circles I had gone in on that thread. I can't remember the last time I had this much wiring trouble. And the harness doesn't look like it was ever tampered with so I don't know why I'm having so much difficulty with this one.

[racebird1]

As you may not know the fule pump signal runs through the air flow meter so it will only give you voltage while the engine is cranking or starting. The flap needs to be sucked open slightly to close the switch in order for the pump to run. This is a safety feature in case there was an accident that would stall the engine and with the key switch still on and if ther was a leak it would continue to pump gas. That is why they ran it through the afm. If you have your cover off of the afm and you open the flap a little with the key switch to on I would think the pump should run.