FastWoman

There's no such thing as vacuum that's too high. The higher the vacuum, the more efficiently your engine is running. If yours starts at 10-12 and makes its way to 15 when it leans out (in response to rising engine temperature), I'd say you're running too richly. Watering eyes is consistent with this! Common sources of a rich condition are... -- incorrectly operating throttle position switch -- stuck-open cold start valve -- coolant temp sensor problem -- too high a resistance, often from a bad connection -- air temp sensor problem -- too high a resistance -- incorrect fuel pressure (bad fuel pressure regulator) -- molested AFM -- usually mucked up by someone trying to correct for a more common lean condition, usually from vacuum leaks

What Oiluj said! If you can start your car with your house key (or possibly even a popsicle stick), you probably have the original ignition lock. New hardware isn't ALL spendy. I think you could get a new ignition cylinder (just the part that turns -- from a locksmith) and door locks (Taiwanese from ebay) all keyed to the same key for maybe $70, as I recall. However, the hatch lock is... well... quite spendy.

Maybe. Is yours a California model with a catalytic converter? If so, the exhaust shouldn't smell gassy. If yours lacks a cat, or if the cat isn't working, you might be smelling a "normal" exhaust. I don't know how old you are, but many/most people who don't remember watching the moon landings also don't know what car exhaust really smells like without a catalytic converter. What do you think resolved the backfire? Did you clean up some sensor connectors? The easiest mixture check you can do is to read the engine vacuum. It should idle in the neighborhood of 18-19 on an old Z engine if everything is running right. Too rich or too lean, and the vacuum will be lower.

Backfire (through the intake) indicates a lean condition. Be careful of those intake backfires, because they can bend the AFM's metering vane. If you have a dead cylinder, the exhaust will go chug chug chug in a regular rhythm. All cylinders firing should result in a perfectly steady exhaust beat. Random misfires is generally a mixture issue. Exhaust blowing hard and spitting occasional water droplets = lean. If your engine is running lean enough to backfire, your plugs will probably be fouled with carbon. Many people are confused by this and think the plugs are reading rich. The textbook "lean" reading spark plug indicates an only somewhat lean condition, while the backfiring and fouled plugs indicates severely lean.

Samson, it frankly sounds like your car has been butchered by previous owners. The L-jetronic fuel injection system is pretty basic/simple, and it can be put back into shape by going through it with a fine-tooth comb (including the intake). If I had to take a guess, I'd say you have a massive vacuum leak (loud hiss) that would ordinarily make the engine run way too lean. However, with the CTS unplugged, the lean condition is compensated, so that the engine will run (poorly). In fact it is overcompensated, so that your plugs foul with carbon after only 10 miles. Both a vacuum leak and bogus temp input are problems. You can't properly fix one problem by introducing another that works in the opposite direction. I'd recommend the following as a matter of course: (0) Drain old gasoline and replace with fresh. Replace fuel filter and inspect for lots of rust (could indicate rust in gas tank clogging up system). Replace air filter. (1) Make sure your intake is air-tight. See post 11 in this thread for a quick method (my "yogurt cup test"): http://www.classiczcars.com/forums/thread43280.html Likely culprits for vacuum leaks are rotted vacuum lines, your rotted PCV hose, and a leaking intake manifold gasket. Brake boosters sometimes leak as well. (2) Make certain all of your EFI components check out. Measure all the resistances, and do all the checks described in the FSM. (3) Check your distributor vacuum advance to make certain it's not frozen up. (4) Change out your plugs, wires, cap and rotor. Use NGK plugs and wires. Verify spark. (5) Adjust your valves, and set your timing (if by this time your engine runs, which it probably should). This all amounts to a major project, but that's what it will take to get your engine running well. Until you do all of this (and more), I don't think you have a prayer of passing California emissions. Heck, my own engine runs like a top, and yet I wouldn't bet my life it would pass your state's emissions tests. So because you'll have to do all this stuff eventually anyway, it's better to go ahead and do it up front. Then you will have worked your way past numerous pitfalls and will be dealing with a much smaller set of reasons your CO or HC might be a bit high, etc.

Wade, my intake is all pretty well gone over. There's no way I have a vacuum leak anywhere, although I admit that's a common problem in these old cars. Everything is removed, cleaned, reconditioned, checked, re-checked, and reassembled. New intake/exhaust gasket, obviously. New injectors and O-rings. The only old working parts I simply cleaned, checked and reinstalled were the cold start injector, throttle position switch, and AAR. She runs like a champ. The only remaining issue is the idle. Oh, and FAIW, my AAR is only good for a couple hundred RPM variation (just like yours), if that. I just live with the idle around 1100 RPM. Sometimes it will drop as far as 800. If I drop idle to 900, it will sometimes dip to 500. It's never died there, but it's "wanted" to.

Thanks, Captain! Yes, I do have a spare AAR. This project might have to wait, though. Although I have two AARs, I only have one toilet and zero showers (but one bath tub). I also have a stack of cement board in the garage and boxes of tile in the living room. I already removed the last remaining rusty bits of 1980 toilet flange, the old rotted bath/shower, the old tile, and the rotted subfloor. Before I start on the AAR, I'm really looking forward to a nice shower.

Yeah, Captain, I can see there's not much room for threading a hole! I'm wondering about a service method that's not nearly as good, but infinitely easier: Looking at the anatomy of the thing, it looks as though I can shoot some oil onto the shutter, let it drip down to the pivot post, and then wiggle the shutter open with a screwdriver blade, essentially working out any rust that might be causing the thing to stick/hang. The problem I'm having with my AAR is that it hangs up and gives me an irratic idle. One day the idle will be running a bit high (when warm), and the next day it will be too low. Then sometimes the cold high-idle doesn't even work. I'm guessing the mechanism is just getting sticky/rusty. Do you think that would be a fair assessment?

Nice, Captain! Thanks for the tour of your AAR. When I have a bit of time, I'll be doing the same.

I'm also using the Standard injectors. Mine work great. FAIW, I've found it much easier to re-install my fuel rail onto the injector hoses after fastening the injectors first into the manifold. The "easy" way of removing and reinstalling injectors and rails en masse was quite frustrating, both on the removal and on the attempted re-installation. This line of clamps is fantastic, BTW: http://www.summitracing.com/parts/cca-g3912 (comes in various sizes) It doesn't cut into the rubber, and it's very flexible -- great for small hoses.

You've just got to trace the power from point to point. The particulars of fuel pump wiring differ from year to year, and I don't know the way a '75 is wired. However, I would bet it's the same as my '78 from the firewall and back. There's a big wiring harness connector (actually two of them) just in side the passenger firewall. You may find a crusty/arcing/burnt connection in one of them for the fuel pump wiring. (The connection is somewhat inadequate for the fuel pump current.) It could be any number of things, of course, but this one connection was particularly troublesome on my car. I eventually solved it by snipping out the wire and connecting via a bullet connector. BTW, to test a relay, just remove it from the car, identify the two coil contacts (should be about 65 ohms between them -- not 0 or infinity). Connect 12V across those two contacts, and measure the resistance between the contacts that should switch on the pump. Resistance should go from infinity to zero'ish. Of course this could be a really fancy relay with multiple coils and contacts, in which case the above might not apply. In that case, identify the fuel pump contact, which should connect to a wire of the same color code as the one you see connected to the (+) side of the fuel pump. On my '78 it's a blue and green wire (blue with green trace, as I recall). Then put the connector partially onto the relay -- enough to make electrical contact, but still leaving enough space to poke at the electrical connectors with a multimeter probe. In the V mode, hook your black probe to ground, and touch the fuel pump contact with the red probe. You should have an indication of power there when you first crank the engine (for 5 sec, as I recall -- but could be different with the '75).

I suspect your fuel pump is fine. However, before doing anything else, please FIX THE FUEL LEAK! I remember when a defective fuel filter leaked on a very nice '66 Mustang of mine and caught the engine on fire -- inside my garage! Luckily damage was minimal. You must respect gasoline, or it will burn up your car and possibly something else. If you want to test your fuel pump, hot-wire it to the battery, monitor its pressure with a fuel pressure gauge between the fuel filter and injector rail (engine not running -- 36.3 psi, as I recall), and monitor its flow rate by connecting a long, clear vinyl hose to the return line of the fuel rail and pouring the return into the gas tank's filler neck. Look for air bubbles (should be none), and watch for a slowing return rate as the pump warms up. But please, fix the leak first!

Tomo, the boot is in the attic over a flooded garage in another town. I suspect it may be a while before I can get you a photo. (It's not currently installed on my car.) I assumed this was standard equipment for the ZX, but a search of images suggests it might not be. There are other makes and models of car that use essentially the same AAR, so perhaps it's not even from a Nissan. Thanks, Obvious, and glad to be back! I just haven't had much time on my hands lately, and my Z has been behaving very well for me. Well, it behaved well until a couple of days ago, when the starter died. I was literally in the process of moving the car to high ground. At least it was a quick repair. Good luck in Philadelphia!

Yikes! You've lost 2' of dune with just this storm so far?! We're getting a bit of wind and water here (Gloucester), but nothing like that (yet). I'll check out the Stebels. Thanks!

Tomo, I have an AAR from an '81 ZX. It came with a thick rubber boot that surrounded the entire part. Captain, I'm impressed with your AAR modification. How did you get the clam shell open? How long does the thing go between cleanings?

Hey Willoughby! I hope y'all are staying dry down south there. (Do you live around Willoughby Spit, perhaps?) So about these horns -- do they hold up over time? A boat is a pretty hostile environment for ANYTHING mechanical, so I hate to draw conclusions from my first air horn experience. In your estimation, how well would these things hold up on a daily driver sort of car that's not a garage queen (until we can get a larger garage built, that is)? I suppose it depends somewhat on usage, and I'm afraid I use the horn very sparingly and infrequently. (Maybe I should make a point of using it more often! )

Hi all, I came across these air horns that come pre-bracketed for Miatas, and I thought they might be good for our Z cars as well: http://www.thompson-automotive.com/Air_Horn.html They sound pretty good, based on the MP3. I was wondering whether any of y'all have used these and have any thoughts about them, either positive or negative. My only experience with air horns was this kit, which I put on a power boat: http://www.ebay.com/itm/FIAMM-66030-3-Trumpet-Car-Truck-Air-Horns-12-Volt-Compressor-Kit-LOUD-/290747241403?hash=item43b1e2d3bb&item=290747241403&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr The horns initially sounded good and were very loud. My only complaint was that it took a split second to pressurize the tubes, so the horn blast didn't begin instantly. After about a year on the water in a very high humidity environment, the compressor (which was well sheltered from rain) began corroding up inside. It developed an obnoxious rattle, but it still worked. After a few more years, the compressor finally froze up, and the horns crumbled from the sun. The Nautilus horns look better constructed, and the tubeless design makes a lot of sense (eliminating that split second delay in the horn blast). I'm tempted to buy three -- one for the Z, one for the Miata, and one for the boat. I'm tired of our sports cars politely going "meep" when some texting kid in a noisy pickup is about to run us over. Any thoughts?

I thought of doing the same thing with real leather. The gauges are obviously the most difficult part. I look forward to seeing whether this works!

The G-nose is still a Z, of course, but to me it really looks like a different car -- a gorgeous car, no doubt, but still not quite what I think of as a Z.

What Grant said! I don't understand why the boot won't seal, though. Are you sure there's not a rip or crack in the boot? I've never had any problem with the wire clamps. In fact I greatly prefer them to the band clamps.

I'm thinking you were in the market for a set of injectors!

This is one of those "personality" things that commonly plagues the 280Zs. There is very little agreement as to what causes it. The theory I favor is that your hot engine block soaks your injectors with heat after you shut down your engine. (They are no longer cooled by the flowing fuel.) This causes the fuel to boil (which many people argue can't happen when the fuel is under pressure; however, the operating pressure of the old L-Jet systems is lower than pressures of modern systems). Then when you go to restart your engine, you're injecting fuel vapor, rather than liquid fuel. Eventually your engine passes all the vapor, cools the injectors back down, and injects liquid fuel. This problem will be worsened... ... in hot weather ... in fuel systems that do not properly hold their pressure ... when running more volatile winter mix gasoline during the summer ... when running 10% ethanol gasoline, for which our EFI systems weren't designed. I've found my hot restart problem has been successfully resolved, for the most part, by the following: ... correcting the pressure leakdown problems (old injectors, worn check valve) ... insulating the fuel rail (very minor improvement) ... running 100% real gasoline -- summer formulation, no ethanol The following measures have been used by Nissan to address the problem: ... plastic (rather than metal) insulators around the bases of the injectors ... cool-down fan on the ZX models (mentioned by black gold man). These fans will mount up under a Z hood.

To me the engine is the soul of the car. A car that's lost its original engine (or one like it) has lost its soul. A Model T with a V8 is no longer a Model T. Same with the Z.

Air should clear the system pretty fast. The tank can be repaired by a radiator shop. It will take some cutting and welding -- probably not cheap.

I onced had a '75 that developed a rust hole in the pickup tube. It "ran out of gas" at about a half tank. It only took until 1984 (?) to develop this problem. I believe the '76 and '75 tanks are probably similarly constructed, but I don't know for sure. That said, your fuel pump might be dying. The pump in my '78 recently died (faded away, really), and it had symptoms similar to yours. The only difference was that I didn't add gas before trying to start my car again. Simply letting the car cool down and rest was enough to resurrect the fuel pump for another 10-20 min, before pressure and delivery volume went south. If you are persuaded it might be the pump, please don't just replace it to see what happens. Again, parts are disappearing, and someone else might really need that pump. Throwing away a functional antique part is very bad karma, so please test the old pump first. Here's how you can test both the hose and the fuel pickup line: Buy a long, clear vinyl hose to connect from the fuel return fitting of your fuel rail. The hose should be long enough to drop the other end into your fuel tank filler neck. Start your engine, and let your car idle in the driveway. Watch how fast fuel flows out of the end of the tube and back into the tank. If your fuel pump has a heat-related failure, the return flow will diminish over time. Mine took about 20 min for return flow to stop altogether. If you have a hole in your pickup tube, with a gasoline level low enough to draw air, you will see air bubbles flowing through the vinyl return line.