FastWoman

Ethanol gas is supposed to last longer than 3 mo, but I've seen it go bad faster than that. The problem is that 10% is often added more than once. Sometimes it's closer to 30%.

... or more easily, unplug the cold-start valve, and test for continuity between that connector and the one you think is the thermotime switch connector. They should both be wired in parallel, so wire A on the thermotime should connect to wire X on the cold start, and wire B on the thermotime should connect to wire Y on the cold start. If you don't get zero-ohmish readings, then you've probably got the temp sensor plug instead -- or corroded connections! (Note here: I've just been into my harness, and I had corroded connections. )

About the vacuum advance: If the breaker plate is frozen, it could be frozen in almost any position, and it could even decide to shift around and stick in different positions from time to time. That might make it difficult to know the engine's timing at any given moment, unless you're aiming a timing light at the crank pulley at the time. I agree with others that it probably wouldn't cause your hesitation, but it's still a problem. FAIW, AutoZone has lifetime warranted rebuilt 280Z distributors for about $100. I'm told the rebuild can sometimes be a bit ham-fisted, though. Check to see that there isn't any wobble in the shaft. I figure the part is a pretty good deal because (1) it's very easy to replace and (2) Datsun's breaker plate mechanism is so prone to failure. So far my rebuild is working just fine.

Hi Jonathan, Thanks for your input/suggestions! I can't say I'm sure of many things, but I'm nailing down issues one by one. Thinking about the mixed rich/lean symtoms, I started wondering whether my injectors are sticking, such that cylinders occasionally get a pretty rich charge of fuel and are otherwise running lean. In other words, I'm wondering whether the fuel delivery is random and inconsistent from pulse to pulse. Another possibility is that the injectors are running fuel and not atomizing it, so that the burn is very inefficient, leaving lots of unburnt hydrocarbons and symptoms of a lean mixture. (Is that possible?) Anyway, I went ahead and started replacement on the injectors and their connectors. I beat a retreat when the mosquitos started attacking, but I should know more tomorrow. Water temp sensor would be next. I'm positive the thermatime and temp sensor connectors aren't switched. It's kinda dumb for them to have put the same sorts of connectors in such close proximity. I labeled the temp sensor connector "temp" just to be certain I don't mess up. It's traced all the way back into the engine harness (which I wired with the new connector), so I know it's correct. (I was very methodical and worked connector by connector, checking, double checking, etc.) Stuck AFM flap? Yow! Hadn't thought of something like that. I'll definitely check that out. Thanks! Cold start valve? Maybe. Massive manifold leak? I wouldn't rule it out. Is there a good way to test for that, not involving introduction of something flammable near the suspected leak? (Remember, I have a leaking exhaust too!) If the manifold is leaking, it will soon be corrected anyway, as I'll be replacing the intake/exhaust gasket.

draztik, your starting problem might be from fuel dribbling out of your fuel rail. I finally replaced the check valve on my fuel pump (screwed into the fuel pump body, not the check valve I referred to above), and it made a big difference for morning starts, but it wasn't the entire problem. I suspect the remainder of my problem is that I have old, dribbly injectors that leak fuel out the other direction, thus flooding the intake with raw fuel and simultaneously removing it from the fuel rail. When I start the engine, it fires up immediately and then dies. Then it takes a few restarts before it will barely run, and then after 10 sec or so of sputtering, it will smooth out and run normally. Here's why I know it's an absence of fuel in the fuel rail that's to blame: When I manually engage the fuel pump for 5 or 10 sec to charge the fuel rail, before turning my key to start the car, the engine will start right up without a complaint. I have no idea about your stalling problem at cruising speed.

Hi all, Here's my predicament: I'm still going through the fuel/intake system of my '78 Z to get everything running right, but I have quite a few items to go. It seems everytime I replace or clean up a connection, the engine runs differently -- sometimes better, sometimes worse -- sometimes richer, sometimes leaner. (Sounds like marriage vows.) I'm now at a point where the engine runs great on startup, but it gets rough when it warms up. The exhaust is sooty, the plugs are all equally sooty (and not oily). The exhaust blows pretty hard in forceful puffs. I wanted to verify that the engine needed a leaner mixture to run better, so I cracked the oil filler cap to introduce a bit of air beyond the air flow meter. I expected RPMs to pick up, but they did not. No matter how small or large an amount of air I introduced that way, it only diminished the idle and made the engine run rougher. I also did the same thing by opening a small vacuum line, with the same result. I'm confused that I can have sooty, rich-smelling exhaust and not have engine function improved by introducing "extra" air into the intake manifold. How could this be? I know my water temp sensor is inaccurate. The resistance reads somewhat high, and that would result in too rich a mixture. I don't know how big a factor this would be or whether my next step should be to replace it. BTW, someone had previously wired a resistor in series to enrichen the fuel/air mixture. I removed the resistor, and that did lean the mixture a bit (returning it a bit more towards normal). My injectors are also old. I have a new set on rail ready to mount up. I believe my old injectors are probably performing uniformly from cylinder to cylinder, as all my plugs look the same (sooty). Do old injectors generally inject too little fuel (from being clogged with deposits) or too much fuel (from having worn passages/parts)? I know my fuel pressure is regulating a few PSI too low as well. The regulator on the "new" fuel rail regulates at a more normal pressure, which of course would enrichen the mixture relative to the pressure regulator I have. It's easy, BTW, just to say to do these things and see what happens, but I want to tackle these jobs in an order that will keep my engine operable. That will make it easier to determine what the problem is (because a non-running engine is hard to diagnose), and it will keep my car mobile, in the event one of these hurricanes causes flooding where I live. (My car is parked at 6 ft above mean low water level.) Diagnostic steps taken: The valve lash is in correct adjustment, and valve timing is within specs. The cam sprocket is mounted on the #1 hole (engine has >160k miles on it), and the mark on the sprocket aligns just even with the oblong mark on the plate behind it when the engine is TDC. Engine vacuum is very low (maybe 14), but that would simply indicate inefficient running, which I already know. Distributor is timed at 10 deg BTDC, per factory specs. I think the engine "wants" more advance. Diagnostic steps not yet taken: Compression test. (Can't find my tester! Grrrr) Various electrical measurements on the EFI, per the FSM. I'm basically trying to get the hardware correct and in place, get all my electrical connections good (all done now, except for on the injectors), and then diagnose other issues from the EFI connector, ultimately maybe adjusting the AFM to fine-tune the fuel/air mixture. Any thoughts as to how I should proceed from here? Most of all, any insights as to how I can have rough idling and sooty, rich-smelling exhaust and NOT improve the idle by introducing extra air into the intake manifold? Thanks for your advice! Sarah

Thanks, Ztrain. I presume you're talking about this stuff? http://www.icslinings.com/pdf/Thermal%20Coat%20Brochure.pdf

Ztrain, my '78 has a sheet metal heat shield between the manifolds, but I don't yet know its shape. Steve, The HVAC material might not be "designed" for that temp range, but I believe its composition is glass and aluminum. I don't think there's anything flammable or meltable. Do either of you (or anyone else) know what temperatures we're dealing with underneath the intake? It sure would be nice to have real numbers, even if they're only approximate!

How about some of the paints on this page: http://www.tcpglobal.com/spraypaintdepot/metallic-effects.aspx There's the anodized look in paints at the bottom -- VHT and Duplicolor. There's also some metal fleck paint at the top, but I don't know what the temperature specs are on it. Then at the very bottom of the page there's a metal fleck overcoat that's meant to be sprayed over a non-metallic base color coat. Hmmmm...

Thanks, Ztrain and Tomo. That would probably rule out the West System epoxy that I use for so many things. (Think boats! ) After a bit of searching, I found this stuff: http://www.alvinproducts.com/Products/Products.asp?ID=2 ... which is good to 1000F. Final curing is done in an oven at 450F. I think that's the stuff! So I would apply this stuff, slightly thinned, to fare out the manifold's rough surface. I would be able to sand it smooth, probably before heat-curing (to make the job easier). I'd then want to top-coat ideally with a deep blue metallic paint and/or powder coating. I'd be going with a deep blue because it would be compatible with the car's current silver color, as well as future plans for a candy-apple-red re-paint. Any thoughts about high temp metallic paints? I also have another thought: I've been entertaining the notion of inserting a piece of semi-rigid fiberglass duct material (for HVAC ducts) between the heat shield and the lower side of the intake manifold to reduce heat exposure. Not only would that benefit the longevity of the manifold's new finish, but it would also increase HP, decrease vapor locking, increase wiring life, etc. Any thoughts about this idea?

I presume you've filed a complaint with the police? If not, you should.

Looks fine to me. All that means is that the sparks are jumping more on the lower end of the terminal (with reference to the photo) than on the upper end. There's nothing excessive about the terminal erosion in the photo.

I just did! I had holes in my exhaust and couldn't pass inspection. So now I have a new 2 1/2" MSA Premium aluminized exhaust with Magnaflow mid-pipe SS muffler. The problem is that my exhaust manifold gasket is leaking. Fortunately they didn't catch that on re-inspection. I'll take another look, but I swear I don't see (or at least notice) the exhaust manifold!

(Bump! ) Maybe I can pull the thing with a crow's foot wrench? How hard would the thing be to turn? The reason I ask about a deep socket is that I would have to buy one. I don't have one that large, so I can't do a test-fit. Whatever I do will require either the purchase of tools I don't have or a bit of engine disassembly, so words of wisdom from people who have replaced this part would be greatly appreciated! Thanks, guys! Peace, Sarah

Thanks, Andrew! I may have to take a parts yard stroll. I definitely need new connectors. I pulled off my water temp sensor connector, and it crumbled a bit. I put it back on immediately. I'm scared to touch it again until I can replace it. I was out driving the other day, and my engine started missing BADLY. I jiggled the connector carefully and was fine for the trip back home. This would be a high-priority project!

Thanks for all your suggestions, guys! Wow, there are a lot of useful products out there! I looked at some examples of high temp powder coatings, and they're gorgeous. The only catch is that they're done on glossy surfaces, and getting the manifold smooth is going to take either a whole lot of sanding and polishing or fairing out with an epoxy filler. Mike, how long did it take for you to polish out your intake manifold prior to ceramic coating? I also stumbled across Eastwood high temp ceramic engine paints: http://www.jcwhitney.com/high-temperature-ceramic-engine-paints/p2023816.jcwx# ... which look great, but I would obviously need to start with bright, polished metal. I presume this is a similar formulation to the stainless finish, Andrew? Can I expect pretty good adhesion out of it? I wonder how it would look on rough aluminum... Hmmmm.... It would be nice to clean up the valve cover and do it in the same finish. Tomo, aluminizing the exhaust manifold sounds pretty cool, except that it's so buried you hardly see it. I was thinking of a high temp black exhaust paint instead. Anodizing... Hmmm... Sounds interesting. Can that be done on rough metal? Whatever I choose, it needs to be something that doesn't take excessive amounts of time. I don't want my car down for too long, as we live on low-lying ground in hurricane country. I don't want to have to evacuate the car by tow truck! Thanks again, guys!

Hi all, I have a leak in my exhaust and have to pull my manifolds ('78). This seems a good time for cosmetic improvements. I considered polishing out the intake manifold, but that's a whole lot of work (as it is sand-cast), and polished aluminum really takes a beating here on the coast. Instead, I think it would look great with a painted finish, something like this: http://atlanticz.ca/zclub/techtips/intake/normal_throttlelink2.jpg I'd love to see other pictures about how this might be done. I have the less attractive '78 manifold with the webbing between the ports. I suppose the webbing is a practical thing, keeping more of the exhaust heat off of the injectors. I was thinking I could black out the webbing and paint the rest a color. This hammered blue isn't bad. Ideas? Of course there's the practical matter of how to fair out the exhaust and which paint to use. There's not a whole lot of heat to deal with, except of course near the head, where the intake and exhaust ports are adjacent to each other. I was thinking of using thickened epoxy to fair out the rough aluminum. Would this hold up to the heat? And then after sanding the epoxy smooth, what paint would be best? Thanks for your suggestions! Peace, Sarah

Hi all, I could use your advice. I just measured my temperature sensor resistance, and it's rather high. Moreover someone apparently "fixed" a fuel/air ratio problem by wiring a resistor in series with the sensor, so that the computer will only see the engine warming up to maybe 120F. Anyway, I presume I should straighten out the wiring and replace the sensor. Fuel/air ratio adjustments can be made at the AFM later. So I'm wondering first how this thing can be removed. Is it possible to slip a deep socket over it, or must it be turned with an open-end wrench? If the latter, do I remove the distributor to get enough working room? Or do I have to remove the thermostat housing from the side of the head first? Next, I'm wondering whether the replacement temp sensors available at my local auto parts store are going to have the same resistances as an OEM Datsun sensor. How can I tell before buying? Or is this a part that should ONLY be genuine Nissan? Thanks for any words of wisdom! Peace, Sarah

I think I found one on Ebay of the original style, but it's gonna CO$$$$T. Is there anything out there cheaper than $17? Thanks!

Hi all, So I got into the beginning stages of sorting out this crumbly mess that's pretending to be the engine wiring on my '78. I've figured out that the connectors on the temp sensor, thermotime switch, cold start injector, etc. are essentially the same as on the main fuel injectors. No prob. I have a source for those on Ebay. However, I'm a bit flummoxed about the 3-conductor connector on the throttle position switch. Where can I find one of those? I can't tell anything from the picture, but is this one? http://cgi.ebay.com/Bosch-1-928-403-968-3-Way-Connector-Kit-/110458797418?pt=LH_DefaultDomain_0&hash=item19b7db7d6a Or this? http://cgi.ebay.com/3-way-Bosch-AMP-Junior-Power-connector-loom-pole-/170344663868?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item27a9554b3c Also, while I'm ordering in connectors, are there any other potentially crumbly electrical parts I might want to source out? Thanks, everyone!

Passed inspection today. Yea! All legal now, I had a chance to punch the accelerator. From what I could tell on the inside of the car, the exhaust sounds fine -- no Honda tuner kid-car character to it. Unfortunately my inspection sticker reads 9-11. Now I have to look at that on my windshield for a year. Kinda takes some of the fun out of driving. :disappoin

Well, if you find a source/solution, let me know. If it doesn't cost a fortune, I might be interested in replacing mine too, just to have it original.

I have to wonder whether raw fuel is ever ejected into the carbon canister if/when the evap tank is removed. For instance, what happens if the car is parked with a very full tank (topped off), and pressure builds in the tank? Does raw gas get burped into the canister? What if the car is parked leaning to the right? What about a hard lefthand curve? Of course if enough fuel is ejected into the canister, it will run out the bottom and onto the ground.

How odd! Does your car have any structural issues? Is it solid? How are the frame rails?

I finally have the MSA premium (aluminized) 2.5" exhaust installed in my mostly stock EFI '78, with a stainless steel Magnaflow glass-pack added as a mid-pipe muffler (rather than a resonator). The system uses my OEM exhaust manifold, rather than headers (which I don't particularly like). I also opted not to install the flex coupler that I was considering before. These are the parts: http://www.summitracing.com/parts/MPE-10416 http://www.thezstore.com/page/TZS/PROD/PEC27/15-6304 I had Tidewater Z do the installation for me, as they had to do a bit of cutting, refitting, and welding. They did a nice job, although they were quite slow getting around to it. Total parts were around $350 and labor $200. The exhaust fits well and sounds pretty good. It has a very deep note at idle, but a bit louder than I had hoped. There's little or no raspiness, which was my #1 concern. It sounds a bit mellower than a moderate "American muscle" tone, and of course with an even tone, rather than the characteristic American V8 "burble." The exhaust gets somewhat louder under load, of course, but still without raspy overtones. Very nice. I haven't yet had my car on the freeway because it's still not legal. I hope to have my inspection sticker Monday. Then I'll be getting on to other projects, like replacing the intake/exhaust manifold gasket (small exhaust leak around #6 --- shhhhh!) and replacing my injectors. Anyway, thanks, everyone, for your helpful advice. I'm pleased with the outcome! Sarah