FastWoman

You don't NEED a multimeter, but this is one of those really cheap and useful tools you should probably have anyway. It will cost you all of $5-$10 at an auto parts store, and it's really handy to stash somewhere in your car, in case you have (or someone else) has electrical trouble. Even if you don't know how to use it, someone else might. I tuned my engine as follows: First, I set the idle mixture adjustment screw on the airflow meter (big screw beneath and towards the driver's side of the outlet of the airflow meter, possibly obscured by a rubber plug) to exactly 5 turns CCW from the completely screwed-in position. Is this the best setting? I really can't say. As far as I could tell, the adjustment did little or nothing. Seriously. Then I hooked up a vacuum gauge to the intake manifold. I disconnected the HVAC control like and connected my gauge to the manifold using that nipple. It's the nipple just forward of the brake booster vacuum hose. Since you have a '78, yours will be configured the same way. Then I started the engine, and adjusted the potentiometer for the best idle. Note: As idle picks up, you will need to adjust the idle speed back down to the spec 800 RPM with the big screw on the top of the throttle body. (Actually I have mine set to 900 RPM -- engine likes it better.) Next, I let it warm up completely, and I fine-tuned the adjustment to produce the highest engine vacuum. Then I turned the control just a tiny bit to the "richer" side (lower resistance -- which you can confirm with that $5 multimeter!). You don't want to adjust so far that you lose engine vacuum. You just want to be a bit on the "rich" side of that "just right" zone. Next, I changed out my plugs, and went for a short test drive to ensure the engine responded well. Then I pulled the new plugs and "read" them to confirm I had a good mixture. You mostly need to note the appearance of the insulator. If it's chalky white, you need to adjust for a richer mixture (adjust the potentiometer to a lower resistance). If it's sooty, you need to adjust for a leaner mixture. If it's a nice, warm mocha, you've got it just right. Before you do ANY of this stuff, you should make certain you don't have any vacuum leaks. You can read about my "yogurt cup test" (note: Yoplait brand fits, but you can really use anything that fits the hole) on post #36 of this thread: http://www.classiczcars.com/forums/open-s30-z-discussions/40234-purs-like-kitten.html This thread chronicles how I got my engine running normally AFTER replacing my leaky intake/exhaust gasket, replacing leaky injectors, verifying/refreshing/replacing fuel/intake parts, verifying my vacuum advance wasn't stuck (and replacing my distributor because it was), setting the timing, and adjusting the valves. Tweaking the fuel/air mixture with the potentiometer was really the LAST step in the process. I'm not saying you can't do the potentiometer modification as the first step in the process. However, you might be putting a bandaid over some other problem -- e.g. richening the mixture to compensate for a massive vacuum leak. Although that might make the engine run better, it still wouldn't make it run RIGHT. You'd still need to work through other possible problems/issues, and you would have to keep re-adjusting your potentiometer every time. So if your goal is to get the engine running RIGHT, you will save yourself a lot of work by doing the mixture adjustment last (and only once). Oh, and back to the multimeter: I suggest you take a reading on the potentiometer, so that you can note the "just right" resistance in your service log book. This way you'll have a record of how your fuel system changes over time (in case you need to readjust later).

The gauge: One of these: Shop Aqua EZ Pressure Gauge at Lowes.com One of these: http://www.iboats.com/BRASS-TEE-1-4-FEMALE-THREAD-Seachoice/dm/view_id.927903?cm_mmc=Google_Main-_-Mall+Product+Listings%3AGoogle-_-+%3AMall+Product+Listings%3AGoogle-_-Seachoice&kw={keyword}&gclid=COCNyOS37boCFYWDQgod4i8AVA Two of these... Brass Coupler 1 8" Hose Barb x 10 32 Unified Male Thread Fuel Gas Water Fitting | eBay ... all in thread sizes to match the gauge, of course! The potentiometer: 1MOhm is probably too much resistance. 1kOhm is perhaps too little. Although the 1MOhm will technically work, the adjustment will be extremely touchy and imprecise. Ideally, you should use a total resistance that's roughly twice what you need, so that your adjustments will be roughly in the center of the range. I use a 5kOhm potentiometer, because my desired resistance is in the neighborhood of 2.5kOhm. I could also probably use a 10kOhm potentiometer fairly well, but I wouldn't want to go higher. A 1k potentiometer would be inadequate to adjust my ECU, but others have used resistances that low. I would say 5k would be a pretty safe choice for most people. If you want to make the installation permanent, I would recommend one of these: Vishay Spectrol M43P502KB40 Trimmer 20 Turn 5K | eBay ... or one of these... 20pcs 3296W 502 5K Ohm Trim Pot Trimmer Potentiometer 3296W | eBay You adjust them with a little screwdriver, and it takes 20 turns to move through the entire adjustment range. These 20 turn pots are extremely stable and accurate, and it would be difficult to knock them out of whack.

The A-pillar cover is maybe 2 ft long and 2.5" wide. My Z is sitting in a garage 10 mi away right now, but it's just a shell with two recessed holes for the screws. Here's a pic of the ZX covers. Z is similar, if you were to cut off the wings on the lefthand side of the pic... 1979 1982 Nissan Datsun 280ZX A Pillars Pair Blk LH RH Windshield 280 Z | eBay I'd be interested in a white dome light (like OEM), but not a clear one (frosted or otherwise). Mine is quite yellowed. I suspect the "cream" color is from yellowing. Surely the original was white. I wouldn't mind an inspection light dome. Mine is shattered. See here: Rare New Datsun 280Z Under Hood Inspection Light | eBay Another item OTHER Z owners might like is a fusible link BODY. See here. The cover domes are cheap and available already, but the bodies are not. The problem is that the ears that screw to the fender can break off. (I don't know if it's a common problem, but both of mine were earless and just hanging there at the ends of their wires.) You would have to find a way to insert heavy electrical connectors, and the owner would have to splice the wires somehow. The issue has become irrelevant to me, because I retrofitted my entire fusible link system with MaxiFuses.

NICE! I'm getting rather excited! With the Bluetooth capabilities, are you going to have an app for that? I would love to help you beta-test in my Z. It's not the freshest engine in the world (about 170k), but it it's straight, with the exception of the wonky ECU.

I went to the hardware store and bought a cheap ($10?) generic pressure gauge (for water?), a brass, 1/8" FPT "T" fitting, and 2 1/8" MPT nipples/barbs. If you imagine the "T" standing upright, like the letter, the two nipples went on the bottom and left. The gauge screwed into the right. Then I stood the T on its side with the gauge pointed up. I hooked the nipple pointing down to the outlet of the fuel filter with a very short hose. I hooked the nipple pointing horizontally to the fuel rail, using a slightly longer hose. The pressure gauge has lived under my hood ever since, ready for whenever I might need it. It's like an umbrella, I suppose, in that it insures I will never have fuel pressure problems ever again. For a temporary test-drive setup, just put a "T" in the line between fuel filter and fuel rail, and run the third leg to a long hose tied to your windshield wiper. Make sure the hose is filled with fuel, and not air, or your fuel pressure regulation will get rather sloppy.

Can you reproduce the black interior finish pieces? For instance, I need a couple of good A-pillar covers for my '78.

3) Your question: It depends on the year. The wiring is different for every year. I believe yours is a '76. Mine is a '78. On the '78, you can short between the two green/blue wires to fire up the pump. I believe your '76 uses a switch in the AFM. You might be able to turn on the ignition (but not crank the engine), and prop open the flap on the AFM to fire up your pump. You can of course also "hotwire" it with a wire temporarily connected between the + post of the battery and the + post of the pump.

The loss of power under load sounds like a fuel starvation problem to me. If your pump is like mine, it will fail slowly, not catastrophically -- a bit like congestive heart failure. Pull off the return line, and attach a hose that runs to a gas can. Then run the pump. (You can jumper the appropriate wires on the fuel pump relay connector.) Observe the return flow: It should be healthy. Keep running the pump for 15 or 20 min, giving the pump enough time to heat up. Again, if your pump is anything like my old pump was, the return flow will get more and more meager and then will stop, as pressure sags below the 36.3 PSI. My old pump would get me out onto the interstate and then would leave my engine sputtering until it failed and left me on the side of the road. When it cooled off, it would pump again. I, too, can recommend the coolant temp sensor resistance tweak. It solved the lean-running issues in my engine. Mine is a '78, and I think this lean-running issue plagues '77/'78 (particularly '78) ECUs. The ECUs are analog, not digital, and they are prone to calibration drift (towards shorter pulses, resulting in less fuel delivery) as the semiconductors age and break down. For all I know, the '77/'78 ECUs might be completely different from the '75/'76. I know they started with Bosch ECUs in '75 and ended up with Hitachi in '78, but I don't know where the changeover was made.

(Deja vu!) Yes, Captain is correct -- either alternator OR oil pressure, or else there would be situations where the engine wouldn't run when it should -- immediately after an oil change (no oil pressure for several seconds), when alternator dies. I also agree with the "start small" suggestion.

^^^ That's my understanding too, Captain. I suspect the pump was made to run with EITHER sign of life because... --- otherwise you wouldn't be able to start your car after an oil change if going on oil pressure only. --- otherwise your engine would die if your alternator failed, leaving you stranded, if going on alternator output only. Personally, I think a better system would be one that monitors the ignition and runs the fuel pump as long as the ignition system is putting out sparks. It could be contained in the ECU. But that's just me.

.Ah, well, there you go! There's no rehabilitating that board. The only thing you could possibly do is to short across the break in the trace, but then you would be getting uneven readings and therefore inaccurate fuel/air ratio.

Your getting occasional readings from the wiper answers my question about how your engine can even run, roughly though it may be. That's quite a lot of money (at least for some of us) to spend. You might be able to fix the old AFM, even if it has been messed with. There is spring calibration info on the Atlantic Z site that I used to calibrate mine. You can also alter the coolant temp sensor circuit's resistance to fine-tune your fuel/air ratio. (The ECU can drift, although this is more a problem with '77/'78 vehicles.) I have to wonder whether the wiper is making firm contact with the semicircular resistive trace. The part is delicate, and maybe it got bent somehow. You might also have a bad contact at the wiper's pivot point and might try some Deoxit there too.

Jan, whenever I've heard an engine whine, I could generally pull off the accessory belt(s) and find a loose accessory bearing just by turning the individual components by hand. The offending bearing would feel rough and loose. I read/hear very often about the long screwdriver trick, but the neurobiologist in me tends to think about this poor guy: Phineas Gage - Wikipedia, the free encyclopedia. I'd strongly recommend one of these instead of a long screwdriver: Mechanic's Stethoscope. It's only $5, which is a lot cheaper/better than a screwdriver launched through your skull. And speaking from personal experience, my little $5 stethoscope is surprisingly good -- a lot better than a screwdriver could ever be.

This only underscores the usefulness of good antitheft features. If someone really wants to work hard at it, they can steal your car, no matter how well it's protected. Heck, they can drag it up onto a flat-bed tow truck, and then it's gone. However, if it's the usual kid wanting to steal it for a joy ride, some sort of defeat mechanism can save your car from destruction. The best defeat mechanism is something of your own design that you don't discuss with others, placed where you decide is appropriate, that doesn't look like a defeat mechanism, but rather an ordinary part of the car. There are also prepackaged defeat mechanisms on the market if you don't have the ability to design one yourself. However, if you have a car that a kid might enjoy stealing, you should definitely have SOME sort of protection!

Your pin 7 is the wiper on the potentiometer. If it is open with respect to pin 8 (and therefore all other pins), then your wiper must just be floating. I frankly don't know how your engine would manage to run that way. Anyway, look at the spring-loaded wiper that follows the semicircular carbon trace as you open the flap. That's not making contact somehow. Perhaps the trace is dirty? You can clean the trace by lightly wetting a paper towel with some WD-40 and wiping it down. Your contacts 36/39 are your fuel pump shutoff. They should open up when the flap is completely closed. This is a safety feature, so that your pump will shut off if your engine dies (e.g. in an accident). You'll see a wire that opens the switch contacts. You can loosen a set screw to rotate the wire a bit, so that it engages the switch when the flap is closed. Pretty car!

One more thing to check, even though it's not backfiring anymore: The breaker plates on these distributors are notorious for sticking and freezing. (I understand that MOST old OEM distributors in running Z's stick and freeze, including my own when I bought the car.) Take your distributor cap off, and try rotating the breaker assembly by hand. It should turn freely, under spring tension, with no binding. If it sticks, your timing could be almost anything at any given time. Your having taken the plate apart and reassembling it could have been what did the trick -- somewhat. It's a fragile and poorly designed mechanism. Also check that your vacuum advance works and that the vacuum tubing to the advance is intact and leak-free. While this wouldn't be "the problem," it's certainly a common problem (in most Z's that haven't been gone over).

A weak ignition will sometimes reveal itself under load, so refreshing the ignition components wouldn't be a bad thing. That still wouldn't explain the backfire. I think that would only happen with a very lean condition. Perhaps the pistons (correct term?) in your carbs are hanging or aren't responding quickly enough?

Andrew, before swapping out anything, you should really check for spark vs. fuel. I like to rule out fuel by spraying a bit of starter fluid into the intake manifold (through a vacuum hose nipple) to see if I start the engine briefly. If it starts, then your spark is intact, but fuel is not. A great way to test whether the ECU is responsive is to plug a Christmas tree light (or a noid) into an injector connector and try cranking. Does it flash? The beauty of these tests is that you're disturbing the system minimally. If you have an intermittent, heat-related electrical issue, you might ruin your chances of finding it by swapping out too many things, wiggling connectors, etc.

I don't know if I'm a tribal elder, but I'd say you should make it what you want it to be. What fun is it otherwise? I don't think minor engine mods detract from the originality of the car in any meaningful way. Body mods might. But I'd say if this car is to be a daily driver, originality is less important than dependability, so mods such as electronic ignition, alternator upgrade, and headlight relays are dandy. It's not going to be a concourse car, so do what you need to do.

If there's not the tiniest spot of rust, then it might be worth it, but that's a pretty penny for an unrestored Z with crimped wiring hanging out from under the dash.

Yes, mine's a 5 speed! So you're saying fuel will flow out the line via gravity for about 5 sec and then stop? Is your tank full? What happens with the gas cap off? Does it keep flowing then? Loose rust can float around in the churning fuel until it progressively clogs the intake screen. Then the engine starves for fuel and dies. When the pump is shut back off, the rust falls away from the screen long enough to let more fuel in, until the pump runs long enough to clog the screen again. Repeat, repeat, repeat. Blue's suggestion would rule out rusty tank issues. If you want to look inside your tank, there's a round inspection lid in the hatch area under the deck lid. It's about 6" dia, with two screws, as I recall. When you remove that, you'll be looking at the fuel level sender at the top of the tank. There's a ring you can turn by knocking it with a screwdriver. Then the sender comes out (delicate -- be careful). Pay attention to the position of the alignment tab. Once that is out, you can look inside with an LED flashlight. Be careful not to make sparks. You can also pull the drain plug on the bottom of the tank, passenger side (10mm wrench, as I recall) and see if rust comes out.

OK, time to start eliminating problems: Got power to your pump? Disconnect the small wire from the starter. Crawl under the fuel pump, and hold a pair of volt meter probes across the terminals of the fuel pump, while a friend turns the key to "start." (It won't actually crank, because you've pulled the solenoid wire.) You should have 12V at the pump for about 5 sec, and then the power would switch off (without a running engine). You can also hot-wire your fuel pump the way siteunseen suggested. Does your pump operate? (Yes, it should. It's new.) With power across the leads, you should hear it running. Is the line clogged from your pump to the engine compartment? Is your filter clogged? Make certain the fuel flows freely. Pull off the fuel hose between the filter and the fuel rail. Put a longer hose on the output of the filter, and put the end into a fuel jug. Run your pump. There should be a voluminous flow of fuel out the end of the line. Passing all of these tests, you should also have pressure, unless there is a mechanical problem with either the pump or the pressure regulator. If I had to guess, I'd place bets that you don't have power to the pump. There's a somewhat problematic connection inside the passenger firewall (at least on my car), and the fuel pump relay connections can also get a bit crusty. And also, as I said, check your ground.

So back to your Nissan pump: It runs when you test it, but not when you install it? You eliminated the issue of it not getting +12, but is the ground good? I don't recall where it grounds, but it's NOT through the case. That second wire feeds through a rubber grommet somewhere in the tool compartment area and then.... ??? I had a problem with fading pressure and volume from my old pump. It would be good for about 30 min, and then would fade to the point the engine would be starved for fuel and die. The pump quickly got weaker after that, during driveway diagnostics, and would only run for maybe 30 sec before the pressure would fade and die. A new (Nissan) pump fixed it.

I'm guessing it's coolant. (Green??) There are a couple of hose connections near the firewall that feed the heater core. In series with the supply hose is a vacuum-actuated stopcock that shuts off coolant flow when your heater is off. You would appear to have a leak somewhere in all of that.

I love these cars: You can put a jungle back in the hatch area!