FastWoman

Thanks, guys! I'll pass your well wishes along. Right now we're hunkered in for the storm. We have plenty of food and gasoline, as well as a generator with about 1000 gal of propane. The only logistic problem might be the trip we need to make to the DC area on Tuesday. The appointment can be bumped back a week if needed. The clinic there has been very good about accommodating the weather-related weirdnesses in our schedule. The intermittent problem with my Z will be difficult to diagnose until it acts up long enough for me to go through a few diagnostic steps. I've eliminated ignition, so it's a fuel problem. Will confirm no gunk in the fuel (which is a bit old) when the weather clears (just need to peek at the Fram G3 on the pump intake). The way the engine was dropping out (as though I were repeatedly turning the ignition on and off), I feel it has to be either the power supply or #1-pin trigger to the ECU. There really aren't any other things it could be, except perhaps a bad ECU (for which I have a spare). As I said, the sailboat is the #1 priority, but that will have to wait until spring. Sailing is sanity for both of us, and the boat has a lot of deep sentimental value. ;-) Y'all stay warm, y'hear? ;-) Sarah

Argh, my ears are burning! (Captain told me y'all were wondering where I've been.) I'm sorry I've been such a stranger, but life really threw us a curve ball. My partner of 15 years was diagnosed with melanoma -- a rather advanced one with a pretty awful prognosis. I dropped everything like a hot potato and went into research/advocacy/treatment/support mode. It's been a hell of a ride so far. The good news is that she's getting the care she needs from the best in this part of the country. Surgery went well, and the surgeon MIGHT (!! maybe !!) have gotten every trace of the cancer -- about a 50% shot. We're shooting for 2020, the 5-year mark, which will be our 20th together. If we can make it that far, we've probably got the thing licked. If she has a recurrence before then, it's going to be a heck of a fight, but one that can actually be won if we are lucky. My Z apparently isn't doing as well. It's been mostly sitting, and you know what happens to cars that sit. I started it up to evacuate it from this coming storm (as we will be having some tidal flooding). The first part of the trip was OK, but the last part ended on a tow truck. Felt like an intermittent electrical problem with the EFI. I'm guessing it might be corroded contacts in the fuel injection relay, for a number of reasons. No time to diagnose, so the car now sits in the driveway at our new(to us) house, to be moved into the garage as soon as I can clear boxes. My back-log includes an oil change on our new-to-us Mazda CX-7, which has become our highway cruiser for our frequent trips for cancer treatment; and a speedometer cable on the Miata, which I probably won't replace until the spring. Ah yes, and then there's the sailboat, which actually takes top priority before any of that, except for the oil change. I've got to reqire the nav lights. Yeah, life just fell apart on us, but we're struggling our way back.

I assume your '77 HVAC is like my '78. There are 2 stopcocks that control coolant flow to the core. The first is pneumatically controlled and is "on/off." The second is mechanically controlled and can be opened and closed variably to control how much heat you get. My guess would be that your pneumatic controls are leaking or disconnected. Part of the problem can be the mode selector switch, which switches vacuums to the various actuators, and which can become dirty and leaky as the grease hardens. It's relatively easy to refurbish. See here: http://www.classiczcars.com/topic/32856-refurbishing-the-hvac-vacuum-selector-valve-in-a-1978-280z-useful-info/

Best mod (about $2): a potentiometer in the CTS circuit to correct the fuel/air ratio. Engine fires right up and runs pretty well. Second best mod (about $10): headlight relays. It's NICE to have bright lights!

^^^ Everything that Zed said! I'll add that 28 is a very good fuel pressure with an idling engine. It suggests your intake vacuum is quite good, which means your engine is running efficiently (good fuel/air mixture). You must have lovely spark plug insulators!

FAIW, the check valve is important mostly for HOT restarts. After the engine cools, the gasoline condenses, and any fuel vapor should be replaced with liquid fuel. When you turn the key, the fuel rail should re-pressurize within a fraction of a second, and all should be good. If it doesn't happen this way, it means you're getting air in the lines, probably when the fuel vapor cools and condenses, and a vacuum is formed. The air would most likely come from leaky injectors. There are obviously other reasons for hard starting, so you should explore those too. Of course none of this is to say you don't need a new check valve, which would help remedy a hot restart issue.

Chas, very cool about the check valves! But believe me that if you tell your "secret" here on the board, the supply will be gobbled up instantly. This sort of thing is better handled through private messages when we know someone legitimately needs a check valve (and isn't just trying to hoard parts supplies). Food for thought.

In my experience (with my Z), almost EVERYTHING was leaky. Replacing the check valve took care of 50% of the problem. A dirty CSV was maybe another 25%. Old, worn injectors were the final 25%. I swapped one old FPR with another old one, and it made no difference. Today my system holds pressure indefinitely. Along the way I tried an adjustable FPR (Chinese knockoff of Aeromotive style), but it didn't even attempt to hold pressure. I returned it. The original check valves are NLA. There's been a good bit of effort on this list to source alternative check valves. When I publicized a plentiful source from Volvo on this list, some predator/parasite consumed the entire national supply in a single day. I was very lucky to get just my one. (I wanted a spare but couldn't buy one.)

Perhaps a long shot, but yes. The afterfire clearing everything up is the confusing part, and I'm grasping at that one straw. The electrical theory is an interesting direction. It could be that your CTS circuit is opening up (bad/dirty connection), causing an excessively rich condition and afterfire. Then when a few cycles fail to combust, raw fuel and air cause afterfire, which shakes the engine and causes the CTS connection to make again. But I don't think afterfire would shake the engine. And if you have this sort of event, you should see black smoke out the exhaust when the engine is losing power. Injector short? Maybe. Stuck injector? Maybe. I guess it could be lots of things. But I'm trying to sniff around what would be most impacted by the afterfire. All I can think of is the exhaust valves, as there is no EGR. Is there any chance your exhaust plugs up and then clears with afterfire? Doesn't seem likely, but just throwing it out there.

Kudos to Chickenman for his EGR theory! That would make sense and would be a much more likely scenario than mine. I'd look at that first! Sometimes the valves do get stuck, but that's usually an intake issue (from heavy varnish), rather than an exhaust issue. Valve adjustment: Every oil change? Really? I don't adjust mine nearly that often -- maybe once every couple of years, if that. But if you haven't adjusted valve lash, you should. When I got my car, I had a couple of exhaust valves that might have been held very slightly open by the too-tight clearances. (The engine ran OK, not great.) That said, the issue I was proposing would have nothing to do with adjustments to the valve lash. I was suggesting you might have a valve or two that doesn't close all the way under spring tension. If this were the problem, you might hear a rattly sound from the valve train when you lose power and a disappearance of that sound after the afterfire.

Steve, the fuel pressure can actually be off a bit without dramatically affecting the running condition, so even a cheap pressure gauge can probably tell you what you need to know. A number of us have installed cheap pressure gauges permanently under the hood for diagnostic purposes. Usually the little gear mechanisms in these gauges wear out. However, the gauge will be good long enough to get the engine sorted out. The way I did mine was to fit two nipples with 1/8" MPT threaded ends into a 1/8" FPT tee fitting. (The 1/8" is nominal, and the bore is really much larger than that -- fits a 5/16" hose nicely). On the third leg of the tee, screw in a cheapo, hardware store variety of pressure gauge, sold for measuring water pressure -- usually in the water pump isle. Total parts will be about $10-15. Insert the gauge inline between the fuel filter and the fuel rail. Again, if it's inaccurate by a couple of psi, it's not that big a deal. It should still give you a good idea whether the rail is up to pressure, and it's always present in the system, ready to yield useful info in the event of another breakdown. With regard to the FPR: It seems a very simple and robust design to me. People sometimes say they have trouble with these things, but I've owned three, and they are all square on 36.4 psi w/o vacuum -- no problem ever. Pressure is given by spring pressure minus vacuum, so it is unlikely one would be inaccurate. (Dunno... maybe spring fatigue? But I've not seen it.) I would think the only ways for it to fail would be leak-down of fuel pressure after shutdown or rupture of the diaphragm (dumping raw fuel into the intake via the vacuum line). To stress-test the fuel pump, I would hook up a gauge, connect a long hose (clear PVC is fine) to the fuel rail return line, and put the other end in the tank filler neck. Then hotwire the pump to run with the ignition off. You can periodically measure flow rate, while keeping an eye on pressure. These pumps often run fine when they're cool and then fail once they warm up. You'll see the pressure hold steady, with a gradually diminishing return flow rate. Then when the pressure drops below 36.4, return flow will cease.

IF the tach keeps steady with the RPMs of the motor, then your ignition is good at least as far as the ICM. Your coil, distributor, rotor, wires, and/or plugs could still be failing you. Of these, only the coil would be temperature sensitive. Try this: Switch your radio to AM, and find a fairly quiet, static-free frequency that lets you listen to the ignition. You might need to turn up the volume a bit. You'll hear a variable-pitched whining noise. Take your car for a drive, and try to reproduce the loss of power. As you lose power, does the whining noise drop out? Be watching your tach at the same time to see if your RPM indication drops out. If your RPM indication doesn't drop out, then your ICM is good. But if the whine drops out, you probably aren't getting spark, most likely because of a bad coil. (Note: I've never tried this diagnostic procedure nor heard it described, but I still think it should work.) I think Charles' (Patcon's) theory about loss of power and afterfire is a good one. What doesn't make sense to me, though, is how an afterfire would have any impact on engine functioning, as it is entirely an exhaust event. Unless... is there any possibility your exhaust valves are messed up? Maybe they are hanging partially open, causing you to lose compression and therefore power, until enough raw fuel makes it to the exhaust manifold to detonate and cause the hanging exhaust valve(s) to slam shut. It's a long shot, but I thought I'd throw the theory out there. Might be interesting to do a compression test. Question: Are you SURE it's an afterfire and not a backfire (through the intake)? An afterfire will sound more like a pop or bang (like a gun going off), while an backfire will sound like a muffled "thump" under the hood. The reason I ask is that a backfire will slam your AFM closed and shake the engine, making it more likely than an afterfire to cause your engine to suddenly run better.

The red hoses aren't what i had feared, but they still need replacement with fuel injection rated hoses -- at least the high pressure one from the filter to the fuel rail. And if there's also a red hose before the filter, that should be replaced too. The pictured hose should be fine for the fuel return line. With our systems running at only 36 psi, it's perhaps not an urgent matter, but it should be tended to.

VERY impressive work! Nice! Your welding guy has talent!

I don't know about others, but my FICD is a very fussy thing to adjust right. It seems it always pulls the idle up too much or too little. I've been tempted just to remove the thing. The idle sag from the compressor isn't really so significant as to require compensation anyway. Moreover, it takes a couple of seconds for the FICD to engage, and the engine bogs (just a little bit) until that happens. And then the device isn't really strong enough to pull up the idle by itself. You have to bump the accelerator for it to make that last little bit of travel. Personally I wouldn't bother with the thing.

Sort of looking that way.

Very nice! I'm anxious to hear how it comes out!

HR, I don't know whether a logic sniffer would be much use on an analog ECU, but this, too, is above my pay grade. Perhaps there are analog sniffers off the shelf? A more likely approach would be to open the cans and cut/grind down the chips under a microscope to trace out all the transistors and resistors. There are 20 transistors and 11 resistors in a 741, so it would probably be necessary to trace hundreds of components -- not fun, but it could be done. Again, above my pay grade. -------------------------------- Chickenman, that magic eye with the eyelid is perfect! It does have an evil look to it, and the deco touch is nice too. My first magic eye was on a reel-to-reel Webcor tape recorder I found at a garage sale when I was a kid. Fond memories.

A pic of the spark plugs would tell us quite a lot.

Wow, that stomps the James Bond theme CL ad I ran for my BMW Z3! Made my day!

Jai, the two red hoses on the side of the engine DO have fuel in them, and one of them might be under pressure (actually should be). However, gravity will not favor the fuel just pouring out until the tank is mostly empty, as would be the case with the 3/8 line under the car where you're going to put the Fram G3 filter. Also, the fuel pump would not be running (as you would/should have the ignition off and the key in your pocket!), so the pressure should only create a small spurt of fuel (maybe a big spurt with those garden hose thingies... dunno). What I do when I remove a pressurized hose is to wrap a rag around it to catch the spurt of fuel, so that it doesn't shoot into my eye. No big deal.

Jai, the big red hose that connects at the top of your valve cover is not a fuel line and not a hazard. I frankly wouldn't worry about it right now. Later! The red "fuel" hoses that worry me are on the passenger side of your engine. You will see a network of tubing shaped like a skinny trumpet on the driver side of your engine. That's the fuel injection rail, and it's pressurized with fuel. Those tubes run around the front side of your engine and meet up with red hoses. Those red hoses should be fuel rated and should also be the correct size (5/16"). At least one, if not two, of them connect to your fuel filter. Those are the hoses I'm worried about. The hazard is that these mystery hoses could leak, split, or pop off their fittings, releasing raw fuel under your hood while the engine is running. Then your engine can catch fire. (Fortunately these hoses don't sit over the exhaust manifold, so there's less risk... but there's still risk. Many a Jaguar has been lost this way, even with correct fuel lines, and I once had a fuel-related engine fire in a '66 Mustang. So I'm very wary of raw fuel. To be clear, your replacement fuel hoses (at least in that area) should be 5/16" diameter fuel-injection rated hose, which sells for about $4/ft. With regard to the starter fluid test: You did introduce starter fluid in the correct place -- directly into the manifold. That part is good. But I wonder whether you actually got enough in there to fire the engine. At this point I think it's looking a lot more like ignition, but we might not have completely ruled out fuel. I usually squirt about 2 seconds (not squirts) of spray into the manifold when I'm doing this, but all of my spray goes in. The spray is very volatile and will evaporate very quickly if you get it on any part of the outside of the engine. That's fine. The stuff isn't dangerous, as long as you don't spray it into an open flame, past electrical sparks, or something like that. Instead of trying to spray directly into the manifold, I would suggest using Jonathan's approach of soaking the air filter. You can pre-loosen your air cleaner bolts and just leave the top of the air cleaner assembly resting on the bottom half. You might clean up the inside of the air cleaner with a damp paper towel so that you don't accidentally suck any dirt into the engine. Then run the engine until it stops, flip open the air cleaner housing, soak the air filter down, flip the housing closed again, and try cranking the engine. You will need to spray the filter enough to get it wet. Or do as others are suggesting: Find a friend to crank the engine, while you spray starter fluid on the filter. Eurodat's advice about the ignition module sounds golden. I'd do what he's suggesting.

As I say, there are a few of us who really straightened everything (and I mean EVERYTHING) out. This is now a known issue with the ECU. As for my own system: AFM spring: calibrated to spec. Wiper trace cleaned and inspected. Output scoped -- very smooth, no gaps. Flaky oxidized wiring: replaced with crimp/solder/marine-heat-shrink connections, all new connectors with crimp/soldered contacts and even some new wire. All now literally much better than new. Flaky FPR: Not likely. The FPR is a very robust part. All that can fail is a diaphram or a spring. My FPR is good and regulates exactly to spec. Fuel pump: Voltage is fine (much of the fuel pump circuit rewired). Pump is actually brand new (old stock Bosch OEM) ECU: Re-flowed solder joints All components verified good at the ECU connector. On the issue of fuel pressure, I could get my engine running almost at a rich enough mix by clamping off the return fuel line and running the fuel rail at about 50 psi. It definitely wanted more fuel. As Captain obvious points out, there are no electrolytics in our ECUs. I've gone through the innards of mine, and no such creatures exist. The electrolytic cap problem you cite is on digital ECUs, and those caps likely aren't used for precision timing circuits. The problem occurs when their leakage corrodes the board. I can't say why Bosch and Hitachi didn't use any electrolytics, but they didn't -- maybe because they realized the devices are prone to leakage and failure.

Jonathan, yikes... I honestly missed that. I didn't realize/catch that the starter fluid test had been done after the engine died. Dyslexia strikes again! Question to Jai: Did you shoot the starter fluid into the hose or into the manifold? And about how long a shot did you give it?

No, I don't have a wideband at this time, but it's on my wish list. Several of us have arrived at the same conclusion. We've gotten there by systematically straightening out everything in the engine -- vacuum leaks, electrical, all of the EFI components checked per the bible, AFM, fuel pressure, injectors refurbed/flowed or new, timing, distributor advance, valve lash and timing (per the 1-2-3 hole positions). And then we still come up short of fuel. We richen the mixture, and then we're fine, give or take. ------------------------- Thank you Chickenman! (But no, I don't know the song... And google wasn't much help...) But tell me a few magic eye tubes wouldn't be part of an awesome vacuum tube ECU -- over the transmission tunnel, under the dash, in a plexiglass enclosure!