SteveJ

Inline glass fuse holder. I can only find pre-wired ones now. I bought some on Amazon 4 years ago that were not pre-wired, but they are no longer available. 250V is the voltage rating. Since you have a 12 volt system, there isn't a problem.

It's Mitty weekend at Road Atlanta. I spent a few minutes with Greg Ira and Scott Hyatt in the paddock after their first qualifying session. Greg was top dog in that session. He may have shown his hand too soon.

Emissions testing would be real there.

If you want to come down this way, I think the Georgia Z Club is planning on going to the PoBoys Cruise In in Canton. I think that's a little over an hour and a half from you. The Cruise In is the 3rd Saturday of the month, and I think we're planning to show up in June.

The output is on the low side. What was the RPM for that voltage? What is the voltage at 2000 RPM?

I know what you were talking about. That's why I told you where you could source the correct size fasteners. https://belmetric.com/coarse-thread-jis-small-wrench-hex-nut-class-8-steel/? https://belmetric.com/coarse-thread-jis-small-wrench-hex-nut-class-8-steel/?sku=NJ8X12YLW (Yellow Zinc) I bought 100 of these.

By the way, if you want the 12 mm head M8 nuts and bolts(JIS spec), you can get them from Bel-Metric.

A friend of mine with over 30 years experience wrenching on Z cars doubles up on the gasket when installing headers. For instance on my L28, I had two Beck-Arnley gaskets with a generous amount of Ultra Copper to adhere the gaskets to one another.

I have been driving the 240Z so much lately that I wanted to take the 260Z out. You can't have them feeling neglected, right? There was a car meet half an hour away. I had the only Z, but it wasn't the only Nissan. There were a couple of JDM Skylines, a Roadster, and a GTR. (Does a G35 count? 😉 )

I'm just glad that you weren't somewhere underneath when it happened.

Good job tracking it down. I can only point you in the right direction. You have to put the effort into it to find the root cause.

Is the horn relay still connected? If the wiring is stock, the only way for there to be a complete circuit is for the green/black wire in the steering column to be connected to ground. When you press the horn button, the button connects the tab on the horn wire to the steering column. You may want to take the cover off the steering column and make sure the combo switch wasn't installed too close to the steering wheel. Is it a stock or aftermarket steering wheel?

That would tell me there's a problem with the alternator.

No. If there isn't a load, such as a light on, a hot fuse won't cause a drain. An internal voltage regulator is still a voltage regulator. A failure of that component could cause a battery drain. For some reason I missed your question. ONLY the circuits in red require the key to be in the ON position to be energized. You can turn on the headlights and parking lights with the key any position. So, going back to my original questions, do you know how to use an ammeter? If not, do you have a test light? One or the other is likely to be necessary to find a cause for draining the battery. Have you checked all of the other items I listed for potential drains? Again, how long does it take the battery to drain?

That's okay. There is the switch between the fuse and the lights. As for battery drains, check the list I supplied.

It sounds like the voltage regulator. I ditched the externally regulated alternator on the 240Z so long ago, I don't remember if there was a clicking sound when I plugged it in (last replaced in 1995). On the 260Z I only unplugged it once and never plugged it back in. They shouldn't be getting warm, though. The 0.5A draw is pretty strong. I bet it goes away with the regulator unplugged. It looks like you are running a points style VR. Have you opened it up and tried to adjust it per the FSM?

Got it. Try spraying a little graphite lubricant into the keyway and moving the key around. Otherwise, consider getting a new ignition switch. https://zcardepot.com/products/ignition-switch-with-keys-240z-260z-280z-510?_pos=5&_sid=1b328e775&_ss=r It's not an exact fit, but it should work.

What do you consider special about 24 inch diameter tires? Something along the lines of 185 70/R14 would be around 24.2 inches. Also 205 50/R16 would be around 24.1 inches.

That's a loaded question. Let me phrase it another way. What circuits can only be powered when the ignition switch is on? The fuses with red only are powered with the key in ON. The fuses in green use the combo switch (headlight/parking light switch). The common fuse is for the cigarette lighter. The clock is on the same fuse as the dome lamp and map light. (I think the wiper park function is on that fuse, too.) So what could drain the battery? Bad voltage regulator Bad alternator Clock (even if it's not running) Dome light, map light, and glove box light (door not closed all of the way - Note: This only applies to the 240Z. The parking lights have to be on for the 260Z or 280Z glove box light to come on.) Aftermarket stereo Aftermarket alarm Aftermarket accessory like remote locks (The previous owner had that on my 260Z. I removed the remote lock and fixed the door lock properly.) Unknown cross-connection Short in the starting motor (unlikely but here for completeness) To help you with the diagnosis When did it start? How long does it take to drain the battery? Do you know how to use a voltmeter and ammeter? Do you own a test light?

Are you seeing the temp gauge creeping up at highway speeds? Could you be running too lean?

No, it doesn't make sense for the fan to run all of the time at highway speeds. You usually have enough air flowing through the radiator then. Are you sure it's running at highway speeds?

Hence why my diagnostics changed to fit the data.

Have you opened the float bowls lid to see if you have fuel in the bowls? Do you think your floats are too high or too low?

I double checked the testing with an 1156 bulb using my parking lights and headlights (all LED). The improvised test light only lit up when I turned on the headlights. My more conventional test light (similar to this - https://www.harborfreight.com/612v-circuit-tester-with-5-ft-lead-63603.html?_br_psugg_q=circuit+tester) lit up with only the parking lights. That means I might have steered you toward an inconclusive test (false negative). You could re-test with a purpose built test light like I linked or with an ammeter. Just because the clock isn't running doesn't mean it's not drawing current. It might be drawing more current if the motor is trying to overcome increased friction.