SteveJ

Your fuel pump is losing power when the ignition switch goes from Start to Run. When you start your car, the coil on the start side of the Engine Fuel Injection Relay is energized, providing power to the fuel pump. When the key goes to the Run position, another coil on the same relay is energized provided that the relay also receives the signal that the engine is running. All you have to do is read through the references I listed earlier, and you'll be on track to solve your problem.

That sounds like a good start.

Look at the Electronic Fuel Injection Relay. That is where the power for the fuel pump comes from. Go to http://www.xenons30.com/reference and download the 75 FSM (2 links on the page). Go to the following link to get a copy of the wiring diagram: http://www.atlanticz.ca/zclub/techtips/electrical.htm.

Not enough insulation. How old are the wires? Could the center wire be nicked somewhere?

There isn't a need if you ordered the extra hardware.

Car & Driver tested the 78 coupe & did a Short Take on the 2+2. Source: http://www.amazon.com/Driver-Datsun-1966-84-Brooklands-Series/dp/0948207515/ref=sr_1_1?ie=UTF8&qid=1335272844&sr=8-1

I'll be there all three days. Look for the Datsun flag.

Just giving a bump to remind people that the show is 2 weeks away.

Are you sure the switch on the back of the ignition switch isn't out of alignment/going bad? Rockauto has them.

For the ignition switch: http://www.amazon.com/Beck-Arnley-201-1179-Ignition-Assembly/dp/B000CB246K/ref=sr_1_1?s=automotive&ie=UTF8&qid=1335104896&sr=1-1 The combo switch is the switch that controls the headlights & wiper. Some also refer to the blinker switch as part of the combo switch since it controls the high beam/low beam circuits. By the way, Rockauto still has a couple of the headlight switches left for $157 + S&H. Look through the FSM and also look at http://www.Carpartsmanual.com for a breakdown of parts. That will help you identify the parts you need to look for.

Then for the dash lights, examine the rheostat.

No, I was looking at the correct area. If you note on the attached section from the wiring diagram. It does not show a wire from the relay going to the connector to meet with the LR wire. I believe that is in error.

If you're worried about ratings, just go with a couple of 30A or 50A relays. Amazon has plenty of SPDT relays with these ratings. You just have to remove and discard the /b (normally closed) contact. The voltage is going to be 12 VDC. These cars didn't play around much with voltage signals. In testing/inspecting the relay, it would probably be smart to do this with the cover off. In examining the wiring diagram I think I may have found an error in the drawing, as there are 6 wires in the plug going to the harness, but only 5 are used. My best guess is that the BW & LR wires energize the coils. The WR wires bring 12VDC to the wipers, and the LW & WB wires go out the rest of the harness. If you have trouble figuring out how to test it, send me a PM with your phone number, and I can walk you through it.

Do the running lights work? They are on the same circuit as the dash lights.

If it's the one Zed Head is talking about, it wouldn't be difficult at all to build the relay out of a couple of standard relays. Depending upon the size of the housing, one could remove the coils & contacts from the standard relays and mount them in the relay. If the contacts are sticking, you could try taking apart the relay and use emery cloth on them. Anyway, relays are relatively easy to replace functionally when they are no longer available.

It sounds like a PO did a swap for a later model alternator. Here is a link to the alternator swap for a 240Z: http://www.zhome.com/ZCMnL/tech/280Alt.html.

The voltage regulator should be on the passenger side fender in the engine bay near the alternator. That said, the PO might have changed to an internally regulated alternator and removed the voltage regulator.

The rumor I heard was well north of $50,000, though I have nothing to confirm what I heard.

The factory service manual (FSM) will tell you exactly how to check your charging system (provided the car is stock). How do you get a FSM? Well, hardcopies pop up on eBay from time-to-time. You can also download them from XenonS30 (link in signature). The full 71 manual isn't available there, but the 72 FSM will work for testing procedures for your charging system. Look for the Engine Electrical section.

Actually, the 78 tank wouldn't fit unless the OP does extensive modifications to the spare tire well. The 77 & 78 didn't have the deep well like the 70-76 cars. The tanks for 77-78 cars are too big for an unmodified car.

You can get most of the different types of connectors that you would need at Vintage Connections. I believe he even has a link to a company that can supply the wire in about any color combination that you might need.

A question to me usually gets a few more directed back at you. 1. How long have you owned the car? 2. How long have you had the problem with the battery draining? Was it like that when you bought the car? 3. Do you have a power antenna? 4. Are you charging the battery every day? 5. How old is the battery? With a battery constantly dying, it's usually one of two problems. There is a load that is not being switched off, or the battery is not charging properly. An alternator that is dying can be a load on the battery. An improperly installed alarm can be a load. (Usually this is a case where something was supposed to be installed on a switched circuit, but it was installed on a constant on circuit.) If the ignition switch does not properly go from Accessory to OFF, relays will be energized that would normally be off. A malfunctioning power antenna can be a load. Of course, an old battery can have trouble maintaining a charge. Internal resistance can cause it to die. For example if you charge the battery, disconnect it from the car, and it still runs down, then the battery has issues. After cleaning connectors as Carl suggested, also go through the FSM section on the charging system. If the S130 FSMs are set up like the S30 FSMs, you'll find it in the Engine Electrical section. Ensure that the alternator is charging the battery properly.

More data is needed here. What modifications have been made to the electrical system? Alarm? Stereo? Amplifier? When you go at it with the multimeter, measure the current through the battery, disconnect the alternator, and measure again. If the reading drops with the alternator unplugged, that is likely your problem.

I put the WESCO model similar to the MSA product in my 73. I prefer the WELR-N. I believe there is standard hardware for seat belt mounting. I don't think it is metric. If you follow my suggestion and order the extra hardware, you'll have a better experience.

The 75/76 tanks have baffles to prevent the fuel pump from sucking air in turns. Search on surge tank if you can't find a 75/76 tank.