Zed Head

Coils don't go bad often, at least the old Nissan coils. But you can test the coil, on the car, pretty easily, along with the injector circuit and ECU circuit. First, though, check that you have 12 volts at both terminals of the coil with the key on. If not, you have a power supply problem. To test the coil, attach one end of a wire (an alligator clip works well) to the negative terminal on the coil. Remove the main, center, wire from the distributor cap, leaving it attached to the coil, and position the electrode on the end close to the engine block or valve cover, close enough to spark and in a spot where you can see it. Turn the key on, then tap the other end of the wire from the negative terminal to ground. Each tap will charge the coil when it touches and discharge it when removed, creating a spark at the main wire. You don't have to hold it to ground, just a quick tap, you're just allowing electricity to flow though the coil for a microsecond. Every third tap should fire the injectors. You'll get spark, spark, spark/click, etc. The coils should swap for short test but they have different specs. One uses a ballast resistor, the other doesn't.

Thanks again. I didn't study the FSM close enough. Plus I think that I might be getting confused by the anode/cathode negative/positive nomenclature, and I looked at a weird web page, that appears to be backwards - http://www.technologystudent.com/elec1/diode1.htm This one looks more correct - http://www.allaboutcircuits.com/vol_3/chpt_3/1.html This one doesn't have enough detail of the diode - http://xkcd.com/814/ This one though, shows a nice picture - http://www.rockauto.com/catalog/moreinfo.php?pk=45765&cc=1209260 I picked up some Radio Shack silicon rectifier diodes, IN4005 - 600V peak voltage, 1A forward current, 30A max., reverse current 10 micro-amps. Anything higher in forward current was too big. They have the same form as the ones in the Rock Auto picture. I'll see what happens.

Thanks 72, that definitely looks interesting for future consideration. I'm deep in to making this broken alternator work with my $6 VR and a few dollars worth of diodes if I can though. I'll probably end up with something as good as the typical auto store rebuilt. If it works, I might take it apart again and replace the cheap parts with higher quality. Some of the VR's alone on Rockauto sell for $70 and the brush/VR assembly for $90, so the odds of good parts in a $50 rebuilt are low. Edit - just noticed that the EBay brush assembly is still l missing the diodes. You can buy the VR, you can buy the brush assembly, but apparently the diodes never wear out.

Thanks for the links, I will definitely be using a heat sink when I put it back together. Shouldn't the end with the line be away from the common point though? The common bracket leads back to the charge lamp, so having the line on that side would allow current to flow from the alternator to the charge lamp, if I understand things correctly. The line is the blocking side, correct? Current can flow through the diode toward the line but can't enter on the side with the line. The tiny diodes in the 78 alt. do seem to have lines on the internal side, toward the windings.

tamo3, I actually do have an 89 Maxima alternator in the garage, modified with the v-belt pulley swap, ready to install. Yes, this is more of an exercise in figuring things out, plus I was disappointed when the alternator failed because it did put out more amps at low RPM than the previous "rebuilt" OReilly alternator. It was a good alternator, probably an original factory alt. from 1978, and seemed like it should still have some life left in it. The volt gauge read fine when it failed, but the charge light wasn't working correctly. That would be cool if you would Steve, I've picked up just enough knowledge over the years to wonder, but not enough to really figure. I just tested the sub-diodes and realized that I wasn't even sure which way the diode symbol was indicating current flow, and blockage. I think that I did figure that one out though. There's a diagram on Page EE-18. I'm still amazed at how much detail Nissan put in to the early FSMs. I tested the bracket that sub-diodes mount to and it is connected to the L terminal on the T plug (the bottom of the T, not the cross-bar).

Something's not quite right if the top of the AFM switch melted. I'm pretty sure that it's designed for very low amperage,just enough to drive the relay solenoid. If you had enough current flowing to melt the top of the switch, you might have a short somewhere, maybe in the relay. If you're not stuck out on the road somewhere right now, you should re-check what's happening, the wires to the switch are pretty small and you could end up melting more things. At least you have more clues now.

Looks like you're taking the right approach, with testing and fixing. The ECU uses a multitude of switches and sensors to determine the injector open time. They all have to be working right for the engine to run right. The best thing to do in the FSM is to combine the continuity tests with the values described later in the chapter for each component. No reason you can't measure values from the ECU connector also. The air temp sensor is in the AFM. The throttle position switch (TPS) can be opened up and cleaned. The coolant temp sensor has a couple of bullet connectors over the manifold, pretty easy to find. It only takes a little moisture to stick an injector. Apparently the insides rust easily. I have unstuck an injector by tapping on it.

There is a band on the diodes. My camera actually gave better magnification than any magnifying glass I have, but I don't see any numbers. I would guess that these three "sub"-didoes as they're called in the FSM are actually for the charge lamp circuit, seeing milliamps one way, through the lamp, to charge up the windings, then blocking the ~15 volts coming back. So your specs. look good to me. Durability in the alternator is probably the key quality. I found a few alternator diodes that looked about right on some Asian manufacturing sites but you have to buy in lots of 1000. I might be spinning my wheels...

Can't really figure out what you're saying, but it sounds like you closed the AFM contact switch by hand and the power wire at the pump shorted on something, melting the end of the wire. Is that about right? You might have blown a fuse or melted a fusible link also. If you're asking why it had power, that's what is supposed to happen if the key is on. When the AFM contact switch closes, after the vane opens, the switch powers the relay and the relay sends power to the pump (or another relay, not 100% sure right now, either way the pump line gets power).

I picked up a $6 voltage regulator to see if I could fix my old 1978 alternator. In removing the VR, the "sub-diodes" came apart (I read the FSM after the fact, it suggests holding the lead with pliers as a heat sink to protect them :mad:). But I think that they might have been bad anyway since the other diodes checked out okay. Who knows. The alternator charged fine, by voltmeter readings, but the charge light went on and increased in intensity with RPM, which seems like a diode problem. Would anyone know where anything about these tiny diodes and where a suitable replacement might be found? I don't really have anything to lose so any WAG is appreciated. I've attached a couple of pictures, of the new VR and brush assembly with the three sub-diodes laying on top, and one of a single sub-diode. Another possibility is the complete brush and VR assembly for ~$41 but I'm trying the super-cheap method first. Parts obtained from Rock Auto. Thanks for looking.

For anyone looking for resto parts for their 240Z, here's a Hybridz member trying to sell some hubs - http://forums.hybridz.org/index.php/topic/109717-240z-front-hubs-for-sale/page__pid__1026748#entry1026748

I think that 75 is wired like 76 and 77. The 15 seconds of running part sounds like either the fuel pump contact switch in the AFM isn't making contact (might be dirty at the contact points), or the fuel pump relay in the combined relay (combined with the fuel injection relay) isn't working. The combined relay is above the hood release handle inside the car. I had the contact switch in the AFM get a piece of dirt or hair or something stuck between the contacts and the car would start, run for a few seconds, then die. I didn't understand how things worked back then so I jumped the fuel pump from my defroster circuit at the back window with a spare piece of wire that the PO had dangling under the car. The Start circuit bypasses the AFM switch and sends power directly to the fuel pump relay. I think that the AFM switch powers the relay through another circuit. You can check the AFM switch by turning the key on and moving the vane in the AFM (take the black cover off of the side and move the weight or remove the big air hose). If the switch and relay circuit is working, the pump will turn on. If the pump doesn't turn on, you could jump the AFM switch at the contact points or clean the contacts. If the pump still doesn't run, then check the relay under the dash.

Will it start using Starting Fluid? If not, the problem is probably spark-related. Squirt some through a vacuum fitting on the manifold. You can listen to see if the pump is running by removing the yellow wire from the starter solenoid and turning the key to Start. You'll hear it. Then you won't have to wonder if the relay (at least part of it) and pump work or not.

Sounds more like a broken wire or loose connection. Have you looked at the moving parts of your throttle linkage to see if it's moving some wires when you "hit the gas"? There's only two things that should affect the gauge needle - electrical current and oil pressure. Oil pressure would be slow so electrical is most likely. Does it happen if you press the throttle when not moving or only when moving? Here's a guess - when you accelerate the wiring at the sender swings back and loses connection. It's part of a big bundle. Or the gauge ground itself is losing contact.

I used a full-size set of Vise-Grips. File any rounded off metal down to give two nice flats on the nut, clean any oil off of the Vise-Grip jaws and the nut, crank the Vise-Grips down tight, heat the metal around the nut with the torch, and apply rotation. If the Vise-Grips start to slip at all, start over, re-position and re-tighten the grips. Watch your knuckles when they let go, they can be very tight.

There's a 71 in the Portland South PnP - http://www.picknpull.com/check_inventory.aspx?Address=97225&Lat=45.506451&Lng=-122.775622&Make=Datsun&Model=280&Distance=200

Have you seen any of the Cardone rebuilt distributors? How was the quality? I've come across a few accounts of poor quality from Cardone's rebuilt products, in general. They seem to have a very large share of the market though, so may be the only choice.

They used points up to 1974. The 1972 FSM has pictures and instructions, might be better than Haynes. Probably the same as 1970. Engine Electrical chapter - www.xenons30.com/reference The breaker plate assembly comes out as one complete unit. Once it's out you can see down to where the centrifugal weights are. The two screws that hold the breaker plate down are out on the edges, they might be buried under that grime. Find the two square projections on the dist. body and look down at the bottom of them, you should see the screws holding the plate down. Can't tell if you already have it out or if you're trying to take it apart in the distributor. The later breaker plates, like used in the electronic dist.'s used a wire spring clip around the bottom of the hole in the center of the breaker plate assembly to hold the two plates together. Maybe you have a newer plate.

More clarity needed. "Before I blew it apart" - what does that mean? "before I took it apart" - is it apart now? You said that you "got a header etc. installed". That implies that someone else installed them. Do you mean that you installed it, blew it apart/took it apart, and when you put it back together these problems appeared? "before I took it apart my electric fan and fuel pump worked fine and now when you turn on the key it does'nt come on at full power". The fan or the pump or both? "It" is singular. If you took it apart and put it back together, describe what you took off to get the header on and any problems you had putting it back together. There might be some clues there. Just trying to help you describe the issue...

Pretty sure y'all are replying to threads that are over 7 years old. Trivia - the rapper Easy-E was a member of N.W.A.

I think that with the Datsunstore you never really know until you call. They're moving to a new location so, who knows, maybe they'll find some old stuff. Worth a call.

The wire in the picture is just the spring for the handle. The end of the rod is a press fit through the plastic piece that is in the hole on the door handle piece. It's L-shaped at the end. I think that I stuck a wide screwdriver between the rod and the door handle piece and popped it out with a twisting motion but it was difficult since I was trying not to break the handle. If I was going to try again I might stick a wider chisel end or scraper in there to twist the rod out, levering off of the inner door handle. When you re-install it, it's just a press fit to pop the rod end through the hole n the plastic piece. Still difficult unless you have strong finger tips. Not much room to squeeze.

Have you changed or even checked the fluid recently? Redline MT90 alone, or a blend of ATF and Swepco 201 transmission fluid (50/50 or 25/75) has "fixed" synchro problems, or bought some time, for me. The fluid can have a big impact on synchro performance. Might be worth a try, for about $30 + labor.

Post #4 here talks a little bit about the light - http://www.classiczcars.com/forums/thread36480.html

Here's a maybe - http://www.datsunstore.com/index.php/cName/7073-240-z1-ac-heating-dash-venting-1