FastWoman

Thanks, Steve! Anyway, the part goes back on the car! Yay!

Steve, the insulation on my main alternator wire was a bit toasty! I don't know whether there was some mishap prior to my ownership, but the alternator was apparently able to put out enough juice that the fusible link did not adequately protect the main wire. As far as I could tell, the fusible link on my car (in stock configuration) was good to about 80A, with the alternator good for 60A. That's all fine, except the 10 ga alternator wire was probably good to 40 or 50 when wrapped inside a harness w/o airflow, even assuming current didn't have to pass through a couple of crusty crimp connections. Trust me that it was definitely "broke!" The problem was in the design. Datsun made a great car overall, but their electrical wiring left much to be desired. Davey, I ended up with brighter headlights, but I don't know how much of that to attribute to the alternator wire. At the same time I did that work, I upgraded my fusible links to maxifuses and installed headlight relays. After I worked through all those trouble spots, my headlights were indeed much brighter, and my electrical system seemed much happier overall. It was like giving an inhalor to someone with asthma.

Thanks, Steve! It's actually page EC-25 that has the info I needed. Fortunately I have the FSM. I was just dumb enough to assume this works like an ordinary check valve (airflow ONLY in one direction) and not to confirm that by reading the section that explains how to test/check it! :stupid: If I had read the paragraph on EC-25, I would have seen that this is a very wonky sort of check valve and that the one on my car is working just fine. It's said there's no such thing as a dumb question, but perhaps this one would have qualified (since the answer was right in the book). Anyway, I appreciate your help!

Vinyl is pretty robust stuff. Your location is "undetermined," but if you're anywhere near the water (coastal or lake), there may be sail and bimini makers in your area that could sew pieces for you very economically.

Yes, check fuel pressure with the engine stopped. That way there will be no intake vacuum, so the fuel pressure will be at its maximum in relation to atmospheric pressure. I suppose there's also good reason to check fuel pressure with the engine under load. (Simply revving the engine briefly at WOT should tell you what you need to know.) If the pump output is inadequate, and if you dump fuel from the fuel rail through the injectors, then the pump might not be able to pump enough fuel to keep the pressure up. If you can observe the fuel pressure and manifold vacuum while the engine is sputtering/hesitating, you should have all the info you need to determine whether the fuel pump is at fault. BTW, the filter isn't any big thing. I think it's $13 at your local auto parts store.

No prob, Shade. I appreciated your help anyway!

Check your system voltage after starting your car. It should be somewhere in the range of 14-14.5 V, as I recall. If it's putting out that voltage, then it's charging your battery and holding up to the electrical load that's on it. Then turn on everything electrical, and rev your engine while repeating your measurement. I would think the system voltage should be AT LEAST 12.5V to maintain your charge while rolling down the street at night with the radio going. The 40A alternators are a bit on the weak side. Other Z owners with 40A alternators might be able to give you a better idea what operating parameters are normal. You just have to keep an eye/ear out for anything that's sounding or operating "differently" and only THEN get paranoid that something might be going wrong. Usually "different" behavior means something has gone wrong, as it would only rarely mean that something has spontaneously gotten better. You should always keep a loose eye on your gauges anyway. You won't get stuck on the side of the road if you catch your alternator problem in good time. You'll be driving down the road, realizing that your headlights are getting dim, and/or your radio is sounding rather scratchy. Then the light should go on that something might be wrong. You check all your gauges, and the alternator gauge is hovering in (-) territory. You then turn off everything electrical, and head towards the closest auto parts store or garage. You're likely to make it, as long as the engine doesn't stall out, especially with a carbureted engine. Your ignition can probably run off of as little as 10VDC. Of course you'll need a jump start wherever you stop your car. You can install the 60A alternator of the later Z models, but your main alternator wire might not be beefy enough to carry 60A. I know the main wire in my '78 (which was designed for a 60A alternator) was not really beefy enough to carry 60A with its stock wiring. I installed a much heavier wire to correct this problem. You'll also need to install a diode on the field coil, as I recall, to keep the power from back-feeding and keeping your engine running even after you turn off the ignition key.

Thanks, guys! Ron, the first image/text you posted hit the nail on the head. That's exactly how my check valve works. It's a bit sloppy, but it's still serviceable. I guess the idea is that the main airflow into the tank is actually through the carbon canister (which would make sense), but the gas cap would relieve the vacuum if the evap emission control system became blocked. (Better than having a buckled tank!) If the tank becomes pressurized, it will relieve its pressure through the carbon canister, but the check valve would keep these air movements to a minimum to keep fuel from evaporating from the tank. Makes perfect sense now. Anyway, thanks for helping me out with this one!

I know the WD-40 is safe, as long as you don't go crazy with it and clean up the excess before sealing the box back up. You'd of course need to clean any oil off of the housing to get the sealant to stick. The best stuff to use would be Deoxit. Fuel starvation could be a fuel pump issue. The fuel pressure is actually regulated in relation to intake manifold vacuum, so the fuel pump has to deliver the highest pressure to the fuel rail when engine vacuum is weak (e.g. engine under load). If it can't deliver that pressure, then the engine would be starved for fuel. Perhaps you could also have a clogged filter that would limit flow rate to the fuel rail, causing fuel supply to choke up under load. Of course a pressure reading would provide that info. I don't think it could be clogged injectors, as they are on/off. The longer they are on, the more fuel they will deliver. If they can deliver a little fuel, they can also deliver a lot of fuel, depending on the pulse duration.

Thanks, Walter! I'll have to check my FSM more carefully tomorrow to see if there is a test for the check valve. Maybe it's supposed to pass air in both directions, but under different pressures. I doubt it, though. With regard to the liquid gasoline vs. gasoline vapor issue, the line from the gas tank system actually originates in the fuel/air separator, so I think that would already take care of the liquid phase. But yes, raw fuel in the canister would be a pretty bad thing!

I think the butterfly closes all the way anyway. The idle screw simply sets the bypass opening, but it shouldn't affect anything other than the idle. A note about timing: For whatever reason, my '78 engine doesn't seem to like the factory spec of 10 deg BTDC. Nobody has been able to tell me yet whether it is normal for the RPMs to bog quite a bit at this setting, vs. a few degrees more advanced. I run the engine at 10 deg, per spec, but it might run quite a bit better at 13 deg. Dunno. I look forward to reading other people's comments on timing, as I often get no answers to the questions I ask. Just a guess about your problem: It sounds like your engine might be fuel starved. Check your airflow meter to make sure the vane moves freely, and also open up the black box on its side, so that you can clean the electrical contacts (wipers) with WD-40. I'd almost bet money the problem is something to do with the airflow meter. And since you have a '78, any idea about my check valve?

Hi all, I asked this before but didn't get an answer. Now I'm trying to decide whether it's worth $35, plus a delay, to replace one part. There's a check valve between the fuel/air separator and the carbon canister on my '78 Z. It's mounted near the fuel pump, and it ensures one-way airflow between the fuel tank system and the carbon canister. The problem is that mine passes air more easily in the reverse direction (towards the tank, in the direction it should actually block airflow) than in the forward direction (towards the canister). However, it does pass air in both directions. So is this thing actually important in any respect, or is it simply federally mandated bovine byproduct? Is there any potential problem that would occur from it driving airflow towards the tank? Is it worth the $35+S&H to replace, or should I simply bypass it (or turn it in the "reverse" direction)? Thanks! Sarah

KJP, yeah, it sounds like a bad ground cable (particularly with the puff of smoke). It's probably corroded inside the insulation. You can always install a cable with a universal end, and that would give you a means to attach the second ground wire.

Upper right: goes from side to side at the front of your center console. It supports the back of the radio. Upper left and the one like it in the middle: Appears possibly to be a bracket supporting the false hatch floor of a 77/78. The curved part on the bottom is more of the false floor assembly and is positioned around the spare tire well. The piece on the left with rubber on it appears to be a support piece for the hinged deck floor lid. Rusty piece in the middle: Appears to be an engine hoist bracket? On the right is a bent up fuel rail. I haven't a clue about the remaining two parts.

Thanks, Mike and John! Yeah, marine environments are brutal! Nothing would surprise me. We're fortunate to live in a fairly protected area (good for our cars), but of course our boats go out on the bay. And yes, cheap SS does corrode. At least now I know more about the grades of SS, so I can be a smarter consumer.

I PM'ed you, Jan...

Yup! The fuel injection system is next. Got my flux capacitor on order. Unfortunately the part is backordered until 2178. Go figure...

Jan, I asked several times on this list about which injectors are good, and there seems to be no consensus. Many people say the refurbished (really just cleaned up, checked, and matched) injectors are just fine, but a few people I trust said to forget the fossilized injectors and just buy new ones. I also understand there's not much difference in quality, so you can just shop price. I bought some off of Ebay that seem to be fine. I haven't yet installed mine, but I'll be getting to that very soon now -- after finishing up with my fuel tank and pump assembly, and then exhaust (which failed inspection). If you can wait a few weeks, I'll let you know how well my injectors work.

Thanks, guys! Well then, no flex coupler (depending on rigidity of engine and transmission mounts, which are in good condition), and a midpipe glasspack. I'm going to go ahead and try the SS Magnaflow. I have my choice with prices: $20 for soft steel (no way), $40 aluminized (OK), and $60 for SS. I figure the midpipe muffler could collect condensation, so I think the extra $20 is probably worth it. I've talked to a couple of muffler guys and a friend who runs a marina, and none have raised concerns with stainless. They all say it's the best way to go. Anyway, that's been my experience too. So I think you just had a bad experience, Mike. Anyway, you seem to like the Magnaflow, as do others I've talked to. Magnaflow SS it is. Thanks again, everyone. I'll let y'all know how it turns out.

I think you have to replace it. If so, I may have a half dozen extra used injectors on my hands on Monday, give or take. Maybe I could send you one. (Part of the "pay it forward" program started last holiday season! )

Hi Mike, I saw the bullet mufflers on the DynoMax website. They only attenuate the noise by 4 dB, which isn't much at all. I suppose that would be good for a tweak (e.g. to interrupt a drone frequency), but I don't know that it would make a major difference. I wish there were stats reported on other mufflers. What sorts of problems do you see with SS and heat? Cracking? My '92 Saturn (which I've owned since it was a baby) has still has almost all of its stock SS exhaust, from headers to tip. I did have to replace the cat because the ceramic honeycomb crumbled. The exhaust note has changed a bit over the decades, but not much. The exhaust is still in excellent condition, even holding up through over a decade in Ohio snow. On the original matter, I think all of you have convinced me I don't need the flex coupler. I appreciate your reassurances.

Ztrain, the muffler provided with the exhaust kit is a DynoMax, model 17733.

Mike, maybe I used a term incorrectly. By "down pipe" I meant the first pipe that leads down from the exhaust manifold to the first straight section of pipe. It has two smaller pipes converging into one. Does "down pipe" mean something special? Anyway my engine and exhaust are 100% stock. I understand from my local Z specialist that a midpipe muffler does a pretty good job of taming MSA's exhaust. Maybe a 3-chamber muffler would also do the job. However, either way I'm going to have to buy something extra. In referring to the muffler, the compactness is in the diameter, not the length. There seems to be plenty of room under the center tunnel for something long and skinny, and the resonator currently under the car is maybe that size (only shorter). Thanks for the link, BTW. Summit is a lot cheaper. Ztrain, the MSA premium exhaust has 2 1/2" pipe. It comes with a muffler, and I had no choices as to which one. It's the DynoMax Super Turbo. Maybe a 3-chamber muffler is in my future. Dunno.

Ztrain, I understand from multiple sources that the MSA exhaust has a rather annoying drone at cruising. I don't have much in the way of sound deadening materials in my car. And yes, I want to kill the raspier notes (e.g. as in Mike's exhaust). I'd never miss the small performance difference, and it's a great investment in happy neighbors. My Mustang had a very aggressive exhaust, and it wasn't really my cup of tea. I apparently put up a link to the wrong page for the muffler (corrected now). Do you think this muffler (a Magnaflow 4" dia x 14" long glass-pack) would be well suited as the "resonator?" It's rather compact and shouldn't have a rust problem.

Thanks, Mike. The flex coupler seems to be constructed of a metal bellows. Would that mean it would bend but not twist? If it only bends, I suppose it would need to be inserted somewhere perpendicular to the axis of the drivetrain, so that it would bend when the engine rocks. There's no way to insert it that way on the MSA downpipe. Or does it twist too?