FastWoman

Just to edit Chas' post a bit...

Additional note: If both bolts were to back out of a cap, the first would drop through the hole. The cap would hang from the second bolt until it dropped with the bolt to the bottom, hence one bolt remaining in the cap. Perhaps the main cap adjacent to the broken rod beat the @#$% out of the rod as it was flailing around, hanging on that last bolt, trying to drop. If the bolt had bent, it would no longer freely back off, and the loose cap would just hang there, beating up on the end of the rod.

Mike, look at the bearing cap in the middle of the pic (post #1, last pic). It still has a bolt in it that appears not to be damaged. If that's the way Leonard found it when he popped the oil pan off, that would suggest the bolt backed out. Perhaps the other 4 did as well? (Are they intact? It looks like some other intact bolts are hanging out in the bottom of the oil pan, pic #3. And didn't two main caps come off, not just one??? Or did you remove one for inspection?) This would have rendered the engine very much like a Triumph inline 6 (with three main bearings, as I recall), only a bit worse, so it still would have run, except with more vibration and less oil pressure. Then the vibration got the best of the rod. Scary!

Don't dead-head the fuel flow for too long, though, because the pump uses the fuel for cooling.

I remember my old '75 280 being EXTREMELY hard to start from a lean condition. I didn't have the hot-restart issue, BTW, but then again, I didn't have 10% ethanol gasoline either. But cold starts were really, really hard. I largely corrected the problem by repairing a bent vane on the AFM (bent from backfire). Sorry to hear about your radiator. My advice: Don't get too fancy. All those cheap, aluminum racing radiators you'll see on ebay tend to be leaky, poorly fabricated things. The best replacement, IMO, is OEM-style. Oh, and another project to add to your list: Clean out the fuel tank. You don't have to get too heroic about it for now, but you might at least drain the crud: Wait until your tank is nearly empty, park your car on a tilt (driver side higher), and drain the crud out of the tank through the drain plug. Jumping around on the bumper should keep the crud moving towards the hole. You can always filter the gas and return it to the tank, sans crud. -------------------------------- Captain, I think my cheapo gauge is Rossiz's $5 variety. For all I know, it's stuck, and I'm fooling myself that it's not. Maybe that's why my fuel rail holds pressure so well!

RCB, when I do the Hellfire conversion, I'll be installing a wide band O2 sensor. Perhaps I'll be able to see those small changes in mixture then. I'm certain it has nothing to do with the potentiometer. Yes, I did read your thread about the CA emissions. I am in awe of you Californian Z owners, meeting modern emissions with your antique engines! Well done!

Captain, I would think the greater sources of wear would be punching the throttle and engine braking, which would cause the gauge to swing back and forth quite a lot. I'm a bit embarrassed to say my cheapo Chinese gauge is still working fine. Maybe I don't work it as hard. Or maybe it's like that little, made-in-Macau plastic toy airplane I bought my son when he was a toddler. When you pulled a trigger, the propeller would spin. That crappy little plastic toy put in several years of very hard service without breaking. Incredible!

Have you had a chance to try what I suggested in post #5? That would tell you whether you have an issue with fuel supply, whether it's the pump, bad electric to the pump, a clogged pickup screen, a clogged filter, a clogged line, or whatever. If there's a problem anywhere in the system, you'll see it in the pressure and return flow rate. If you can re-create the problem in your driveway this way, then you can narrow down the cause, component by component. If you can't re-create the problem this way, then you're probably looking at the wrong system. (For instance, maybe the EFI is at fault.) Also, have you read your plugs yet?

Just something else to add to the equation: When you first crank the engine, if the temp is below that fuzzy 57-72 degF range, your CSV will be spraying fuel until the thermotime switch warms up enough to cut off the switch it off (probably a matter of numerous seconds). As a result your mixture changes quite a lot over the first numerous seconds of cranking, going from very rich to perhaps rather lean. And then if you prime your system without physically cranking the engine, the CSV might be accumulating a puddle of fuel into the intake manifold, resulting in a super-rich condition, and that might be what kicks the engine over. It could be, as Zed suggests, that your no-start condition relates to an incorrect mixture. Try unplugging your CSV to see if that makes your no-start condition go away. Also try spraying enough starter fluid into the intake to start your car after it has sat, and see if that gives it a big enough kick that it runs on its own after the first couple of seconds on ether. FAIW, when I prime my fuel rail, I hear bubbles rushing through and clearing until the fuel pump sounds even out, and yet I can start my engine even before the bubbles have cleared. I have no idea where the bubbles come from.

There aren't really THAT many connectors. IMO, replacing all the rubber and connectors is a wise move. It will save you a ton of time/effort in the long run.

RCB, Interesting about your bypass screw! I've adjusted mine in and out -- from all the way closed to screwed out almost to the point of falling out -- and it doesn't impact my idle mixture the tiniest bit! I wonder why. It doesn't seem to be clogged or anything. Although it would be great if your check valve held pressure longer than 5 hr, I think 5 hr is certainly enough. As I understand it, the Nissan dealerships had a policy of replacing them if they didn't hold pressure for at least 2 hr, so they would have considered your check valve still good. Their only purpose was preventing hot restart problems, which apparently you're not experiencing (much).

I don't think there's anything about an old car that should keep it from starting reliably, but this may be a case of an old DESIGN not starting as easily as a modern one. Back in the day, we would frequently have to bump the starter a couple of times to get running. An interesting mod might be a push-button under the edge of the dash (or somewhere where it is not easily pressed by accident) that would actuate the CSV. We could use it like the priming bulb on a lawnmower! Of course it would be easy to prime too much and flood the engine.

Sorry you're still having hot restart issues, Rossiz! As an alternative to a starter kill switch, you might wire a switch to deliver +12V to the coil of the fuel pump relay. It would be a priming switch, so to speak. (That's what I did on my car.) I'm anxious to hear what does the trick for you, since you'll be trying a few approaches.

Captain, that was an absolutely smashing video!

Actually the E-type was much better than the average British sports car. As I recall, it had a 4-wheel independent suspension like the Z and disc brakes all around, although the rear ones were very weird, internal sorts of things (a nightmare to re-pad and not good for dissipating heat). Not a bad engine either -- chain-drive DOHC, hemi head, 7 crank bearings. I think it would give you a good run for your money. If it didn't catch fire or have the Lucas systems die, it might just pass you and splatter motor oil all over your windshield as it pulled ahead. You might out-wiggle it on the curves, of course, and in an autocross event, you'd easily pass it during breakdowns, ultimately being first across the line.

I'm glad you've come to love your wire wheels. IMO they look great on a Z! The design of the Z was certainly influenced by the designs of other lovely 60's era machines, including the E-type, the Ferrari 250GTO, and the Toyota GT2000. The Jag E-type makes me a bit weak in the knees. I could have bought a decent one for about $6000 back in the 80's, but I thought it had too much rust. In hindsight... But still, I agree with you. There is nothing nicer than a lovely classic car you can actually drive around without being terrified of a door ding or a splash of water. If these were incredibly valuable cars, they'd be no fun at all.

Such a beautiful little girl, Len!

I think before trying it, he's trying to collect an entire bowl full.

Depending on the child, the first few weeks can be hell. I recall being out of commission for about 3 months with my first born. Lenny does seem to be one of those "life gets in the way" sorts of people, as he had started this project once before this before putting it down for about a year. However, the light at the end of the tunnel is so near that I think he'll see it through. Of course that doesn't help when you need your AFM back to pass emissions. Anyway, Lenny, I'm thinking positive thoughts and sending good vibes your way. Keep on plugging, man! We're counting on you!

I'm glad we ferreted out the problem! Damn that Ohio road salt! It's still taking its toll on my Saturn. It's odd they'd make this circuit soooo sensitive. The conductivity of the short had to be > 2 MOhm! Maybe they wanted to pass as little current as possible to minimize corrosion in the contacts -- to make them last longer. Anyway, congrats on getting your Z back on the road! Enjoy the ride!

^^^ good idea! Heap, you asked about the possibility of a stuck-open injector. I think if your pump is healthy, it should be able to supply all the injectors in their full open position at 36 psi. However, if in doubt, look at your plugs. A bad injector will be associated with a plug with very different looking deposits.

Er... Please ignore my #6 (last post). Obviously the involvement of a connected TPS falsifies that possibility. Thinking about Captain's theory, assuming the ECU is delivering WOT enrichment correctly, there is nothing different >3kRPM (vs. <3kRPM) that would suddenly deliver excessive fuel and choke out the engine. However, if you look at it from a standpoint of engine load, perhaps 3k at WOT is where the engine begins to suck in enough air to move the AFM vane to a dead spot in the potentiometer, thereby mucking up fuel delivery. Maybe the 3k mark is just a cruel coincidence. There's one thing I'd like to know: Does this happen only under load? Can you recreate the issue out of gear in your driveway? Can you lay the pedal to the floor and have the engine bounce around the 3k mark as though it's rev limited? If you can do this, then it would be interesting to plug a lightbulb in to one of the injector plugs and observe its behavior when this happens.

I suppose I should add... (6) There's a possibility that the "logic" state for the idle circuit has become unresponsive and is either permanently high or permanently low. That is, your ECU might be bad. I've never heard of one failing in this way, though.

Heap, you've probably got a bad check valve on your fuel pump. The Nissan part is NLA, but there are other alternatives available -- see recent thread. That said, the check valve is only important for preventing hot restart issues. It would in no way impact the ability of your engine to run correctly, once started.

First dumb question: Fresh gasoline? Second dumb question: Have you confirmed you have fuel pressure (36 psi while cranking)? If you check the factory service manual, which you can download for free from xenons30.com, you will find a procedure for testing your individual injectors in the Engine Fuel (EF) section. You can actually ground them individually and, if all goes well, hear them click as you ground them. I imagine if they click, and if there's any fuel pressure behind them, they'll spray fuel. However, I suppose there's also a remote possibility they are all clogged up. (Was the car running recently, or has it been sitting for years?) Here's a test you can do: Fire up the fuel pump to pressurize the system, and then shut it off. Hopefully the fuel rail will hold pressure for you. Then short an injector to ground. When you do this, you should see the fuel pressure bleed off. That is a confirmation that the injector is actually spraying fuel. BTW, the cold start injector is only actuated when the engine temp is below 50F (which it's not been these days, at least in Virginia), and even then, it's not actuated for very long.