SteveJ

You are correct. Mid-grade is typically a blend of premium and regular. I am fortunate enough to live near a boating area so I can get 90 ethanol free or 87 ethanol free. I can even get 110 at a pump about 10 miles from my house.

The running lights/dash lights circuit is problematic in the S30s. I had to replace the fusebox in my 73 about 27 years ago after it melted down at that circuit. The front side markers tend to get corroded. The rear side markers could, too. The corrosion can bridge the positive and negative wires to bypass the bulb. It isn't a dead short, but it is very low resistance. The wiring to the running lights should be green with a blue stripe. You photo seems to show a green/white wire, but it's difficult to repair. You may want to consider using LED bulbs for the running lights and using a lower rated fuse. Also inspect/clean the side markers. Here is something I wrote up a few years back on the subject:

The test light is a poor man's ammeter. The process I described to him was designed for him to come back to us for more advice. That way we could evaluate the circuits and see if we could find the offending component.

Less than 1 mV is the same as noise. If was an analog meter set on the lowest voltage scale, you probably wouldn't see any meter deflection. Things that can drain the battery and you might not notice: A bad door switch that leaves the light on (mentioned) The clock, even if it's not running. (That's on the cigarette lighter fuse.) Voltage regulator going bad. Aftermarket (or previous owner) modification such as stereo or car alarm. How do you detect what's causing a drain? Well, probably one of the most elegant ways is to construct a test light to replace a fusible link. Parts: 1156 bulb socket (https://www.amazon.com/Socket-Harness-Sockets-Adapter-Connector/dp/B09BCMWFP5) 1156 bulb (https://www.amazon.com/Bonlux-10-Pack-Dimmable-Landscape-Replacement/dp/B0928RWLG3) Clip leads (https://www.harborfreight.com/28-piece-electrical-clip-set-67589.html) You want an incandescent bulb because you want low resistance in your test light. Attach a clip to each wire of the socket and install the bulb in the socket. With the doors closed and key out of the ignition, pull a fusible link. Clip the test light to the fusible link block. If it doesn't light up, put the fusible link back and move to the next fusible link. If the test light turns on, note the color of the fusible link and take a picture of the fusible link block so that we can tell which link it was. Once we know which link, we can let you know how to drill down better to the guilty circuit.

Georgia Z Club meeting tonight. There was a good showing of cars. Here are most of them. The two black/gold AEs were both purchased relatively recently. There was another couple of S30s that showed up later, and a couple later models parked on the other side of lot, so I couldn't squeeze them in. When I came out to take this photo, a gentleman named Tom came over from the gas station because he saw the Z cars. He owned a 71 in high school and college. I told him to look up our club on Facebook. Maybe he'll visit.

Yes, they are. I linked @26th-Zup with them when he was looking for some parts. I've also helped them with some customer's cars.

Where in GA? Resurrected Classics? Max is a member here, but he rarely posts.

Make sure the dome light isn't staying on. That can cause a "mystery battery drain". The incandescent bulbs aren't that bright, and you might not notice it in the day. I have seen that as a current draw in someone's car before. It was caused by a wonky door switch that the plunger wasn't breaking the circuit like it should.

No, it is not. Did you take a measurement of voltage to ground at the solenoid terminal on the starter with the black/yellow wire removed?

This may help you: https://forums.hybridz.org/topic/124734-understanding-the-260z-and-280z-wiper-circuit-reverse-polarity-park/

The black/yellow wire should only be energized if the key is in the start position. If you have a voltmeter, see if there is voltage to ground at the black/yellow wire. Also check for voltage to ground at the terminal on the starter where the black/yellow wire lands. One of two things may be happening: The switch on the back of the ignition switch is going bad and supplying voltage (but with a very small amount of current) to the black/yellow wire. The starter is going bad and somehow is backfeeding the solenoid, again with a very small amount of current. I didn't see any obvious cross-connection possibilities in looking at the wiring diagram. I hope no one ever decided to re-wire things to "make them better".

Yep, that's the expected level of Arizona corrosion. 😉 Did you try running it and checking the voltage at the battery while it's running?

Just putting this out there for people to remember when diagnosing electrical issues, I have seen this on a couple of cars now. First a 260Z with no turn signals. The hazard lights worked. We looked for continuity from the switch to the bulb socket. The test failed, so I took apart the connectors to see where we were losing signal. All of the harness sections tested good. We plugged the harnesses back together, and the turn signals worked. Next a 280Z with an intermittent temperature gauge. After testing for a while with mixed results, I separated the dash harness from the engine harness, again with inconclusive results. After I plugged the harness back together, it worked. Don't forget to unplug harnesses and reconnect them. Some contact cleaner or Deoxit doesn't hurt, either.

Start the engine and see what the voltage at the battery is with the engine running. It wouldn't hurt to see what that looks like. @Dolfinz - Could you take a photo of the negative terminal of the battery, the end of the battery cable at the starter and where the smaller wire attaches at the firewall? Bad grounds can cause a lot of frustration.

I need to take pictures. It hasn't reached the top of my list, yet. It will after I get a customer car out of my garage.

When I started out on the mailing list it was all dial-up. That took too long to get to see the boobies. You also had to remember to program in the code before the dial up number to stop call waiting, otherwise your online time would get interrupted.

If it doesn't it means you have some more wiring bugs to squash. Make sure you still have good voltage to ground on the black/white at the ballast resistor.

That's because it will be 18 years. 😉 According to your profile you joined in 2004.

I was on the big mailing list before I joined Mike's mailing list.

Thanks, Ron ( @zclocks). That makes a lot of sense to me, especially with my fail on the 200SX clock. I'll have to take another look at it. Are you interested in any photos of the guts of the 200SX clock?

Here's an interview with one of the ad creators: https://www.linkedin.com/pulse/joy-ride-story-most-loved-car-commercial-ever-made-rob-siltanen/

Sorry, it's not my write up. I have one of those clocks sitting on my parts shelves, waiting for me.

The 77 FSM does show the ballast resistor.

My family had a 68 Mustang when I was growing up, so I always had a special place in my heart for Mustangs, despite what idiots were doing at car shows. Back in 2011 when I wanted a new daily driver, I got the new Mustang with the 3.7L V6. It's a pretty good car, but it's no 68 Mustang. I appreciate it for what it is and for the honor it shows to the original. The new Z will never be like the old Z, but I like how it pays respect to the heritage. I also plan on judging it for what it is and not what cars once were. I think it could be a great modern driver in that respect. I'll also still enjoy driving the originals whenever I can.