Think I have a short

[FastWoman]

[[My thought is that the ancient ignition relay is sticking and causing the fuse to heat up until it finally clicks]]

I'd be very skeptical if it were to happen that way. On the other hand, corroded contacts in the relay might result in arcing. You can probably open up the suspect relay and clean the contacts. You might have to bend a metal tab or two, but no biggie. I'd still be surprised if it were the relay, though. Relays are pretty robust. The only relays I've seen killed switch things like heavy electric motors (with huge start-up currents).

Also don't forget the rare fuse that will look good, test OK, and still be bad. Sometimes the strip running through the glass will break contact with the end, due to metal fatigue (from the thermal cycling). Since you've identified the fuse, try swapping with another fuse of the same value. Better still, see if you can replicate the problem, and then test both ends of the fuse with a multimeter. If they're at different voltages, the fuse is bad.

[EScanlon]

WHAT Ignition Relay are you referring to?

The 71 isn't equipped with one unless it's aftermarket add-on by a PO, and if so, then referencing the OEM wiring diagram may be useless.

The Ignition Switch connects that B/W wire you are referencing(when in RUN position), to power from the White/Red that comes FROM the fuse box, and by doing so energizes the IG circuit of the car (refer to the wiring diagram). That circuit includes the gauges that Steve pointed out as well as the Fuel Pump circuit (your car is equipped with the wires but there isn't a factory fuel pump in a 71) AND the Automatic Transmission kick-down switch and Temperature Relay (to switch to the second set of points).

However, the ONLY relay that is energized by the Ignition Switch in the 71 is the Accessory Relay (which is the one people hear clicking inside the cabin). That is on a different wire also from the Ignition Switch (L/R), but it only comes on when the Ig. Sw. is in RUN.

However, the 3rd fuse (up or down still the same fuse, there's only five per side) on the RH side of the fuse block is the 20A Park/Tail lamp fuse which controls the Engine Bay Lamp, Instrument lights and as labeled the Park and Tail lamps (not Stop).

On the LEFT side of the fuse block, the 3rd fuse is the fuse that's powered by the B/W wire coming from the Ignition Switch.

So, ignore the accessory relay clicking on when the ignition switch is in Run, and instead concentrate on the wiring coming out of the fuse block. You might also do as Sarah mentioned and check that 3rd fuse (middle fuse) on the LEFT side of the block.

E

[SteveJ]

Thanks Steve I will clean them up tomorrow. I came up with the same wire colors when I was tracing the system a bit(need to get my hands on a wiring diagram) so you are saying black/white wire from ignition relay to fuse block then green wire to all the components? The relay that gives the black/white wire power clicks when ignition is turned on but the times that the components don't work the relay does not click...That is why I am thinking it is sticking. I am not sure if that would make it heat up...as for the connectors, I wire and equip police/gov vehicles for a living so my shop has all kinds of connectors...I was not worrying about being period correct at this point just using what I have. If you need any amp pin connectors let me know I have tons.

Actually, the colors could be off. I forgot you had a 71, and I was looking at a 73 wiring diagram.

XenonS30 doesn't have a 71 wiring diagram. It would be great if someone who owned a 71 FSM would post a scan of the wiring diagram. (If someone posted a copy elsewhere on this site, it's able to hide from my searches.)

In the meantime, you could look at the 72 FSM, understanding that there could be differences between it and your car.

As E put in his post, forget about the existence of relays with regard to the ignition. Relays were used for accessories and the horn. Your car has 12VDC from the battery to the ignition switch. When you put the key in the RUN position, the circuit is completed to black/white wire, carrying the 12VDC to the fuse block and out to many different circuits.

[KAL7467]

thanks for clearing all that up guys and gals I think I nowe better understand the system and am going to clean all the contacts today at lunch...also if it makes a difference in wireing diagrams my car is a 71 modle but was made in 9/70 and is a series one with the vents on hatch lid e31 head ect...if that makes any difference....on a side note someone mentioned wires for a electric fuel pump but no pump is it common for early z owners to add one?

[FastWoman]

I don't know if it's common for early Z owners to install electric pumps, but I think *I* would do that on any carbureted vehicle that periodically sits (e.g. during the winter), and I would have the pump on its own switch, perhaps on the IGN circuit, so that it can be shut off:

When you're finished driving and will leave the car sitting for a week, you can kill the engine by starving it. Just kill the fuel pump, and let the engine run until the gas in the carbs is gone. No varnish problems, and no ethanol-gas corrosion.

When you're ready to use the car again, turn the key to energize the ignition, switch on the pump, and start the car only after you hear the pump sounds "firm up."

BTW, an electric pump can double as a fuel transfer switch and, with the proper valving, can give you an easy way to drain your tank in the winter.

I have an electric pump on our powerboat, in series with the mechanical one. I use it for priming the carb. However, this ethanol gas has utterly ruined the carb by sitting in it and soaking up atmospheric moisture through the vent tubes. The ethanol reacts and turns to formic acid, which corrodes the metal parts. I found the float chambers on my carb literally stuffed with aluminum corrosion. You couldn't even see the floats for all the gray flakes. VERY sobering. I'm rebuilding the carb this weekend, and when I reinstall, I'm removing the mechanical fuel pump. From now on, whenever we return to dock, I'll be killing the engine by starving the carb. I'm even considering whether we should install a stopcock to seal our tank vent during non-use. (Opinions are varied.)

Anyway, ethanol gas is EVIL! Anything you can do to keep it out of your carbs during down-time would be a very good idea.

[Mikes Z car]

FastWoman,

Thanks for the info on ethanol. I have thought of putting a "T" in the rubber gas line that runs between the carb floats on a 240Z and the bottom of the carbs, keeping it capped and tied off in an up position for normal operation and when it sits over winter dropping it down and uncapping it to drain out the ethanol. I have heard of putting a little oil in the gas tank to cut down corrosion I wonder if that would help with corrosion from ethanol?

Mike.