FastWoman

Congrats!

Congrats on the trip! I've always thought the Z is the perfect road trip vehicle. It's a pretty robust car, as long as you've got everything working to begin with. Sorry about your misadventures with the truck.

Ah, OK.... I saw the points replacement comment and forgot that the 260Z has electronic ignition. Clomolina, try this: Lift the wire(s) off the - terminal of the coil, turn on the ignition, and measure the voltage of the - terminal. It should be +12V if you have not mixed up your wires. The wires you lifted off the terminal should all be 0V. If so, you're good. Now reattach the wires to the - terminal, and add an additional piece of wire there. Strip the opposite end of the wire. Pull the coil high voltage wire off the center post of the distributor, and hover it over a ground point, maybe a couple of mm away. Now turn on the ignition, and tap the bare wire (connected to the - post of the coil) to ground somewhere. (DON'T TOUCH THE BARE METAL OF THE WIRE WITH YOUR FINGERS.) As you tap the bare wire to ground, you should see a spark from the high voltage coil wire to ground. If this happens, your coil is good.Assuming your coil is good, now work forward: Remove the extra wire from the - terminal of the coil, and leave the high voltage coil wire perched above the ground point. Now crank your engine. If you get a spark, the transistor ignition unit and distributor pickup is good. As Chas points out, you might have the dual pickup system. I forget.Assuming you've got spark to the distributor, the question becomes whether spark gets from your distributor to the plug wires. You might have a bad distributor cap (dirty/cracked/old/worn), which might be shorting your spark to ground. IMO, you should consider replacing the cap and rotor for good measure.

I suppose I disagree with the FSM, which is a first! (Does it really say 12.5V?) Your alternator voltage should be AT LEAST 13V, perhaps at least 13.5V, and usually 14 - 14.5V. An alternator putting out 12.8V can keep the system going, I suppose, but it's going to be really slow recharging the battery and will leave the battery less than fully charged in practice.

FAIW, you might have a weak spark that is difficult to see, or you might have trouble seeing it in strong sunlight. The starter fluid test would rule out quite a lot of things, and starter fluid is a very handy thing to have on your shelf. Your points ignition system is pretty simple. It works like this: When you turn on your ignition, the + side of the coil receives +12V. As your engine turns, the cam in the distributor turns, opening and closing your "points," which are a switch. When the points close, they ground the - side of the coil, allowing current to flow through it. When current flows through the primary side of the coil, a high voltage is induced in the secondary side. Then when the points open, the interruption of current induces another high voltage. There's another part, called a condenser, which interacts with the coil to generate a better spark. The high voltage results in a spark that is routed via the distributor's rotor and cap to the correct spark plug.Your coil should be good (new), but there have been cases of bad ones out of the box. Your wires are probably good (new). It's not a bad idea to replace the distributor cap and rotor on a vehicle with an unknown history. Check your points to make certain they open and close correctly, and make sure that they are clean. It's probably a good idea to replace your points and condenser anyway, BUT you have to know how to adjust your points and timing! If you (or your dad) don't know how to do this, or if you don't have a dwell meter and timing light, then work with the points and condenser you have for now. Check your wiring to ensure that the points ground the - side of the coil. Check your ignition wires to make certain they run to the correct plugs and are in the correct firing order. "Blue" has posted a nice diagram somewhere on this forum. You might be able to search it. Here's an illustrated discussion of how your ignition system works: http://auto.howstuffworks.com/ignition-system4.htm

Exactly. When you talk about the coil sending power to the distributor, I'm picturing you trying to measure the static voltage of the ignition wires. However, there is (or should be) no conductivity between the primary coil (the + and - screw terminals) and the secondary coil (from ground to the high voltage cable). It would be NORMAL to read zero volts between the high voltage cable and ground, or else your coil is defective. (But please don't put your meter across these points, as you might accidentally zap yourself or your meter!) The "coil" is really a step-up transformer, with the primary and secondary coils coupled inductively. If you can narrow down between fuel and spark, we can help you to debug from there. But so far there is nothing that tells me you're actually lacking spark.

There are two ways to test for spark: 1. Pull one of your plug wires, and perch it with the metal as close as possible (but not touching) to a ground point (e.g. your valve cover). It can help to insert a small piece of wire (e.g. paperclip) into the boot and have it hovering over a ground point, maybe a mm or two above it. Then crank your engine. You should see a spark there with every two rotations of the engine. Another way is to use a spare spark plug (or remove one). With the plug wire on the spark plug, and the spark plug sitting on your valve cover, crank the engine, and look for a spark between the electrodes. 2. Spray some starter fluid into the intake, and try starting your engine. If it runs for a couple of seconds and then dies, your ignition is fine, and you really have a fuel problem of some sort.

FAIW, on-board MAP sensors supposedly use those little tubes, and they respond very quickly to changing vacuum. Diameter shouldn't be a significant issue. One precautionary note: Several of us have installed cheap fuel pressure gauges on our fuel rails, and these have commonly worn out. (Mine still survives somehow.) These have gear-driven needles, and the gears wear out with the frequent cycling of fuel pressure (which changes with manifold vacuum).

The 280 gets no love?! I know I'm a bit different from most people, but I look at a less desired car this way: You buy it for less, don't risk as much when you drive it (meaning less heartburn and more fun), and have every bit the same cool factor. When a car gets too valuable, I don't feel comfortable driving it as much. I had a nearly perfect '66 Mustang that just sat in the garage (= no fun). My very nice, but not perfect, '78 280 is much more fun, because I won't freak out if someone leans against it (well maybe just a bit), and I can drive it to the grocery store without being terrified a shopping cart will bump it. If I need to replace a hose, I don't have to worry about it being an authentic braided one. I just buy a hose from the local parts store -- easy breezy. And what wonderful cars these are to maintain! There's ample space under the hood, and the systems are simple and reliable. A Z is much easier to maintain than a modern car, even with scarcity of parts. My car is not an investment. I own it for fun, not to make money. I'm OK with that. I prefer my fun to be cheap. The day my 280 becomes precious, I will sell it and find another cheap/fun car. That said, I already own it. It's a Miata, and I'll sell that one too when it becomes precious. Yes, the early EFI is quite primitive. But a carb is even more primitive. I'd rather have the EFI any day. Once you get it working right, it's a fairly robust system, with the exception of hot-restart issues (deriving from changes in fuel formulations over the years -- an annoyance more than anything.) Just realize, it is difficult to get ANY of these cars (carb or EFI) to pass emissions. That doesn't mean you can't do it. It just takes a bit of work. Someone recommended a 2+2. I hate the look of the things, but some people really like them. If you're one of those people, it would be great to have a back seat for your kids. (Of course these old cars aren't as crash-worthy as most modern cars.) Also these cars all have accommodations for small/medium dogs, who LOVE to ride in the hatch area if you're not terrified of getting nose prints on the glass. They have a 360 view! Great fun! My bottom-line advice: Forget the investment. Drive what's fun, whatever that might be for you. If you're the average hobbyist, you're not going to make any money from your car anyway. You'll do well to break even and have a "free" car to drive (which is what I usually do). PS I'm not taking your poll. Don't let others decide for you. After gathering everyone's thoughts, YOU decide. YOU'll be the one behind the wheel, hopefully with a big smile on your face.

It sounds like your throttle linkage is sticking, for one thing (won't come down to idle when you remove foot from gas pedal). All the linkages are mechanical. You can watch what pushes, pulls and turns when you step on the pedal (with the ignition off). You should clean and lube the entire mechanism, from the gas pedal, to the pivots on the firewall, to the throttle body. And make certain your return springs are strong enough to close the throttle. As a newbie, you should download a copy of the beloved Factory Service Manual (actually written by Nissan). You can download it for free from xenons30.com in their reference materials section. It is very thorough and very well written. I would change all fluids and filters. When you change the fuel filter, shake it out to see what falls out of it. If you see a bunch of debris, you may have rusty gas tank issues. You may also have rust in your injector rail, as those filters apparently don't last forever. Oh, and... Welcome!

What awesome news! Congratulations, Scott! Woohoo! I hope they catch the rat! Captain, I use the same defeat strategy on our boat lift. My concern is that someone could flip switches to run the lift, and then leave. The lift would then destroy itself and possibly part of the dock with it. So it doesn't run unless you plug in the dongle. My Z uses a different defeat strategy that I won't discuss with anyone (or else the secret would be out there). However, this dongle strategy is an idea that can be shared. Every dongle would be wired differently, and just knowing the defeat strategy would not help a thief.

I have a gear reduction starter on my '78. I had replaced it and don't remember whether the original was a gear reduction model. FAIW, I had a Chrysler 318 inboard boat with a massive Prestolite starter that was in fairly nice shape. I would frequently clean out the starter to refresh the armature, brushes, connections, etc., but it would still crank the motor rather sluggishly. My cables were hefty and clean, and I was cranking off of two batteries -- one a starting battery and the other a deep cycle. One day I decided to ditch the pretty Prestolite starter and install a gear reduction starter, and it made all the difference in the world. When I turned the key, the starter would spin the engine effortlessly.

If the ignition wire between your coil and distributor cap is messed up, then that's a very likely cause for your loss of spark. If I were you, I would replace the rotor, distributor cap, and wires. You've already replaced the plugs, which is good. These parts can get rather tired, and it doesn't really cost a lot of money to replace them. It can potentially make a huge difference in how well the engine runs, even if it's not your main problem. If you still have no spark after replacing these items, then I would verify the wiring of the ignition system. Above all, make sure the transistor ignition unit and coil have power. If your ignition circuit has power and is correctly wired, but you still have no spark, check/replace the coil and/or transistor ignition module. +1 regarding your ignition lock. Your locks are probably all worn out. You can buy replica door locks and take those, plus your ignition lock, to a lock smith, who can rework the ignition lock and rekey everything to the hatch key. It's not very expensive, and it's SO GOOD to have working locks that can't be turned with house keys, screwdrivers, and popsicle sticks.

Mark, extraneous bulls**t is part of the charm of any vintage object -- like the inspection lids, tool boxes, and service light! I'd be leary of a remote start button beneath the hood for theft reasons, but otherwise I think it would be a fun feature -- a conversation piece. Of course if someone is already underneath your hood, I suppose it's pretty obvious how to energize the starter, even without a button.

I don't believe anyone mentioned this, but replacing the spark plugs WILL NOT drag down your electrical system and cause your engine not to crank. If your battery is strong, your cables and connections are good, and your starter is good, then your engine should crank vigorously when you turn the key. It might not start because of other issues, but at least it will crank. Check your cables for corrosion. Sometimes a cable will be corroded just beneath the insulation near the battery connector. I believe you can have an auto parts store test your starter. If it's necessary to replace it, a gear-reduction starter from later Z years ('77/'78?) would be a nice upgrade, provided it will bolt up. (I don't see why it wouldn't.)

FAIW, Chevron Delo 15W-40 is a high detergent, high-zinc dino-oil formulated for diesel engines. I've found it cleans up my engine's innards pretty well, and it seems to be about the closest thing to the older formulations intended for cars such as ours. I feel the detergent content can be just as important as the zinc, as our engines typically don't burn very cleanly. Without proper scrubbing and suspension, the combustion products can precipitate out and polymerize in the engine. (That's how my Z's engine came to me from the PO.) I used Castrol GTX when I was a kid, and I ran the @#$% out of my poor '75 Z, putting significant miles on it. I never had a cam wear problem. I don't use Castrol GTX anymore, but I'll sometimes use Castrol Syntec in other engines. I once saw some pretty scary test results in which Castrol GTX wound up right at the bottom for protection of high pressure surfaces such as cams. That made me give up on the product. But I will say it really kept my engine clean -- very high detergent.

I'd go ahead and replace the plug wires as a first step. Bad wires can give you a weak spark and misfiring/stumbling under load. If that doesn't clear the problem up, then consider your injectors. I've had very good luck cleaning fuel varnish with Chemtool B12.

^^^^ I did that when I capped my '75 dash back in the 80's. After a month in the Texas sun, you could see every line of glue.

I'm guessing that "losing pressure" means "losing power," so when the OP steps on the accelerator pedal, the engine bogs and backfires out the exhaust. I would bet money that there are multiple problems that have to be solved one by one. The first is the question of why #3 and #6 plugs are wet. No, they are not "companion" cylinders in any sense. QUESTION: Do the new plugs in #'s 3 and 6 show any combustion deposits, or do they look like brand new plugs soaked in fuel? If they are deposit-free, I would suspect an ignition problem. I would replace the spark plug wires, if possible with NGK brand. (You've already replaced everything else from the coil forward.) I would probably do this on a new-to-me vehicle anyway, as plug wires do have a limited lifespan, and most people neglect to replace them. Your wet plugs in #3 and #6 would easily explain the backfire, as you're blowing raw gas and air into the hot exhaust, which occasionally ignites/explodes there. (This can damage your exhaust, BTW, so you want to fix the issue quickly.) If you've got combustion products on #3 and #6, then you might be dealing with fuel issues, e.g. stuck injectors. QUESTION: Do you have fresh gasoline, or are you trying to run the car off of the gasoline that came with the car?

Welcome, Darren! You've got great taste in sports cars! Glad to have you in our little community! Sarah

Your ignition lock was probably close to worn out anyway. After decades of service, they get to the point you can turn them with the wrong car key, a house key, a popsicle stick, a screwdriver, etc. Many locksmiths will be able to replace your key cylinder with a new part. Then to theft-proof your car, I would wire in some sort of defeat circuit or switch. Many strategies are possible. I think one that might work well is to wire your starter wire to a momentary switch. If you hold the switch while turning the key, the engine will crank. If you don't hold the switch, the horn will be energized when you turn the key. I would think the would-be thieves would bail as soon as they turn the key and blow the horn once. One wonders whether thieves nowadays know how to hotwire an old car with carbs and points ignition. It's pretty easy. However, an electric fuel pump and electronic ignition (e.g. a reluctance distributor and an HEI retrofit) might give you two more things you could disable that would not be as easily hot-wired.

Right. Being given another option (that you don't have to exercise) would seem like a good thing. Otherwise, if you can't pass emissions, your only choice is to admire your car as it sits in the garage. Eh.... We overlapped! Either way, I don't envy Z owners in emissions states!

Lenny, consider the following hypothetical: Let's say airflow is pretty much maxed out (or has approached some asymptote) at some RPM at WOT, owing to Reynolds numbers. And then RPM increases considerably beyond that point. As long as fuel delivery isn't maxed out (e.g. injector pulses not overlapping), then fuel delivery will increase (because of more injection pulses per minute), while air delivery will not increase. Or looking at it from a different angle -- what goes on during one combustion cycle -- the same volume of air will have to be shared with many more combustion cycles, hence less air per cycle, while the fuel delivery per cycle remains the same. Either way you explain it, that would create a richer running condition -- again, if airflow is limited, but fuel delivery is not. At some point our systems just can't spray any more fuel, because the injector pulses would overlap. About what RPMs would generate that overlap with the AFM pegged out? (I'm sure you've tested it.)

There are no rev limiters in our primitive systems! You wouldn't want one built into the ignition, as you'd end up blowing raw fuel out the exhaust, which of course can detonate. Our ECUs are pretty simple: Every rotation (3 sparks), a dose of fuel gets delivered according to the input of the various sensors.

A suggestion: In their never-ending quest to make local news entertaining, the news stations in our area often feature stories about someone having had something sentimental stolen (e.g. a class ring), with a plea to the public for tips. If the stations in your area do this sort of thing, your story would be well suited for local news -- a local man who lovingly restored the sports car he bought new when he was ___ years old. If you add a personal story or two and a $10,000 reward, no questions asked, and you'd have a LOT of eyes out for your car. You might just get it back.