FastWoman

Chad, we were taking a long drive yesterday in my Z, and the engine just upped and quit on us, sputtering for about 10-15 sec and then leaving us to coast to the side of the road. See my "humble pie" thread in the "help" section. I found my fuel pump was running at a slightly higher pitch, slightly louder, with a faint "growl," rather than its usual, quet, rubbery rumble. This growl sound is apparently a no-load condition for the pump. The interesting thing is that the pump WAS running. I don't know whether it was cavitating or pumping air or what. Anyway, we might have the same problem. FAIW, if you're pulling a vacuum of 16, your motor is running strongly enough not to die. It sounds like you've got something else going on -- just like you're suspecting, an interruption of fuel suuply to the engine. As long as your fuel pump relay is pulled in, it should be supplying steady current to the pump. I've never known current from a relay to go weak while the relay remains actuated. Sometimes relay contacts can become burnt and not make a good contact in the first place, but what you have when the relay makes is what you should have until it breaks. The drop in voltage when the fuel pump is making noises is particularly interesting. It could be that the pump is drawing more current, perhaps because it is getting jammed up with some crud or something? Your problem might also relate to a rather overstressed electrical connection for the fuel pump wire, as a part of those two very large electrical connectors just inside the passenger firewall. My connection had started arcing at one time, and eventually it melted that part of the connector. I cleaned up the connector a couple of times, only to have it fail again. My solution was ultimately to clip that wire out of the connector and to use a bullet connector to make the connection. That connection hasn't failed me since then. So it would be interesting to know whether your engine refuses to run even when you can hear the fuel pump running. You might want to do what I did. It was a simple thing. Just wire a momentary switch to supply +12 to the fuel pump relay's coil. You can use the switch to prime your fuel rail if you lose pressure. You can also use it to run your pump manually, just to confirm it's operational.

Well, I felt my vacuum reservoir was rather ugly. It has the same milky, translucent appearance. I painted it black, and it looks 1000% better, but just not stock.

Update: NOT a blocked vent. I sucked air through the gas cap, per the FSM. It vented freely. I ran a few short distances today in the Z. It started and ran each time. I primed the fuel pump each time to listen to the tone of the pump. Before one of my starts, the pump made the slightly higher pitched, slightly louder, more growly sound for a couple of seconds, and then it settled into a lower pitch, softer, more rubbery rumble (its normal tone). This seemed to be the difference between no-load and load. So when I was stranded by the side of the road, I would presume my pump sound was telling me no-load -- no pressure, no fuel supply, but running pump motor. I suppose another possibility is a failed fuel pressure regulator that got stuck open and dumped all the fuel pressure. However, the engine sputtering yesterday would seem more symptomatic of air bubbles than of fuel pressure going south. Any other thoughts, anyone? Thanks!

All hail the parkbench bumpers! It could have been a lot worse, as Eric said! It still sucks, though, but it could have sucked a lot worse!

Hmmmmmm...... Hadn't thought of that, Zed! And no, I didn't remove the gas cap alongside the highway. I did notice when I previously filled up that there was a pretty strong "whoosh" when I opened the gas cap. I didn't notice in which direction. That's definitely on my "to check" list now! Thanks! The thing is, though, do you think a vacuum in the tank could kill the engine that suddenly? It was literally within the span of 10-15 sec. EDIT: Oh, and I get what you're saying about the return vacuum pulling against the back of the regulator. Hmmmmm.... To the FSM to think about this one!

PB, I "think" the ECU dumps lots of fuel when the AFM is unplugged. On the other hand, I *know* this happens when the coolant temp sensor is unplugged. What happens if you plug back in your AFM, unplug your coolant temp sensor, and then give it a crank? Alternatively, what happens if you leave both plugged in and disconnect the vacuum line from the fuel pressure regulator. These will both run the engine richer. If you can get the engine to run by doing any of this, I'd say your engine is fuel starved. The reason "why" might be a bit more difficult to determine. FAIW, the carbon/soot in the AFM won't affect running, but it's probably a reflection of a history of backfiring from lean running. Oh, and don't use the turbo AFM. Your ECU isn't calibrated to use the signal from anything but an N/A AFM.

So we're headed out I64 to see family in Richmond for Easter, with an almost full tank of 93 octane. I'm feeling pretty confident in my '78, which has run like a top ever since I straightened it out early last September. (My inspection sticker says 9-11, BTW.) Along about a half hour from our destination, as we're tooling along just as happy as can be, my engine starts sputtering and then dies within a 10 or 15 sec period. As I'm rolling, I try restarting a few times, to no avail. I coast to a stop along the shoulder, and I'm unable to restart. At this point I have about 7/8 of a tank of fuel. I had been checking gauges periodically, because I had noticed my voltage seemed a tad lower than usual at idle. (I was keeping a good eye on the alternator, which was still putting out 14V when the engine died.) I gave all the gauges a fast check as the engine was sputtering, but not quite dead: Fuel, check Coolant temp, normal Oil pressure, normal Voltage, normal An additional note: I noticed my tach bouncing quite a bit as the engine was sputtering. It does that when the cylinders are running extremely lean, causing a bit more kickback at the end of the spark's "burn time." My tach has a retrofit Mopar board in it and is very sensitive to misfire this way. Indications were pretty clear this was a fuel starvation issue and not an ignition issue (or else my tach wouldn't be bouncing at all). Here's the smoking gun: Some of you may know/remember I installed a fuel pump priming switch that lets me manually actuate my fuel pump (e.g. for clearing a vapor lock) or switch it off entirely (e.g. for clearing a flooded condition). So when I hit this switch, I could definitely hear my fuel pump run. However, instead of a soft, low, rubbery rumble, it was a very slightly higher pitched, slightly louder growl. My SO and I both noticed this, so I wasn't alone. I tried priming the fuel rail with the switch and restarting, and the engine would crank, crank, crank, and maybe go "vroom," then immediately die. I was able to get a few "vrooms," and then couldn't get anything after that. Ordinarily my engine starts immediately with about 1 revolution. I thought there was an extremely small likelihood my engine might have flooded somehow. So I switched off my fuel pump, cranked for maybe 10 sec to clear the cylinders, re-primed my fuel rail, and gave it another go. Nothing. At this point I'm thinking I'm somehow pumping air (hence the fuel pump sound). I'm reminded of an earlier time when I owned a '75 Z in the mid 80's. The siphon tube in the gas tank rusted through, and I ran out of gas with a half tank. The symptoms were exactly the same. There was nothing to do except call AAA for a flat-bed truck. I wasn't about to start working on my car on the shoulder of an interstate highway. A couple hours later, my car was sitting in my driveway back home. I stuck the key in the ignition, fired up my fuel pump (which sounded normal this time), and the engine went "crank, crank, crank, sputter, sputter, vroom" and was running like a top. :tapemouth I had been ready to spend the rest of my free time today diagnosing the problem, but there's no sense in that if I can't replicate the problem. So here's my thought: Because of the sound I was getting from the fuel pump, I'm betting either the pump is going out, or I was sucking up air in the lines. I saw/smelled no signs of leaking fuel either alongside the insterstate or back at home, so I'm pretty sure the problem, whatever it is, is contained internally. If the problem was my fuel pump, perhaps it corrected itself once the fuel pump cooled down? Can these pumps fail and then start working again if the motor doesn't fail? Working with the theory that my pump was drawing up air because of a rusty siphon tube: I saw inside my tank when I removed it, cleaned it out, and reinstalled. (It was surprisingly rust/crud-free, BTW!) The fuel siphon went to a structure in the middle of the tank that looked like a tall coffee can, where I imagine the intake screen was located. I couldn't see any thing inside the can and don't know if the siphon tube goes anywhere high in the tank, where it would have the opportunity to rust and admit air. Does it? My engine failed when I was cruising at about 70 on flat ground. When I pulled off on the shoulder, the car was sitting on a slight slope towards the righthand side. Perhaps that made an air siphoning problem even worse. Then my car was loaded onto and unloaded from a flat-bed tow truck, so that its nose was pointed maybe 25 or 30 deg in the air for a few minutes. Perhaps that allowed fuel and air to move in such a way as to get things working again? Anyway, I'm totally frustrated and confused. Does anyone have a clue what might have happened or what I might check? Can anyone describe how the pump (and not motor) portion of a fuel pump might fail and how it would behave? Can anyone describe the internal plumbing of a 1978 tank? Help! I'll add what the problem is probably not ("probably" not, because I haven't been given the opportunity to properly diagnose the system): It's not rust in the tank, because that tank is BEAUTIFUL inside. Hard fuel lines were blown out. Rubber fuel lines were replaced. Vent hoses were replaced. New fuel filter. Squeaky clean fuel rail with new injectors. All electrical connectors on engine new. New coolant temp sensor. My air regulator probably needs replacement, but there's no way that killed the engine at highway speeds. Refurbed/cleaned up AFM. EVERYTHING on that engine carefully gone through, checked, cleaned up, brought to specs or replaced. All new ignition components (HEI retrofit) with new wiring. Everything's been working great since September on this daily driver. Thanks for any help/ideas, y'all!

Leonard, I bet the Coke worked because of the phosphoric acid. I wonder whether a bit of phosphoric acid (without the sugar) would work a bit better still. I think once the engine broke loose, I would neutralize with baking soda, suck out any fluid from the cylinders with a small tube on the end of a wet vac, spray the cylinders liberally with WD-40, and drain the crankcase immediately. I've never tried it, obviously!

Chad, I think you've established now (with the coolant sensor unplugging) that your fuel pump, filters and lines can supply the volume of fuel needed to keep your engine running. At some point when I was in the process of getting my engine straight, I could get it to start and run OK when it was cold, but as it warmed up, it would run really roughly. I would also increasingly get backfire through the intake as the engine warmed up. This would happen sometimes when I would goose the accelerator pedal. My engine started running this way when I removed a fixed resistor that some mechanic had put inline with the coolant temp sensor. This was a field fix used to richen the mixture. In this state the cold enrichment was just enough to run the engine relatively smoothly when cold, but when the enrichment ended the engine ran very poorly. I ultimately fixed my system by adding resistance back inline with my coolant temp sensor, which scales the fuel delivery up throughout all operating conditions. Search my profile for my "purs like a kitten" thread, which describes everything I went through to get my engine straight. It turns out that the (probable) culprit in my engine was an ECU that had drifted in its operating characteristics over the decades. This seems to be a common problem, and the added resistance seems to be the preferred field fix for that problem. But before you get to the point of diddling with the resistance of the coolant temp circuit, you need to go through your engine with a fine tooth comb to make certain you don't have some other problem, like a massive vacuum leak.

Blue, I agree with you that there could be a fuel delivery/metering issue, but there's definitely also an ignition problem. That's the first thing to correct. Once the engine is firing on all 6, we'll be able to determine more. I'm somewhat surprised that 6 is getting spark and power to the injector, because the plug looks like there hasn't been any fire in the cylinder. I also suspect 4 and 5 COULD appear sooty from extremely lean running. Although it's a counterintuitive interpretation, an extremely lean can lead to a slow and incomplete burn, thus generating lots of unburnt hydrocarbons. I only know this because my own engine was running extremely lean and had similarly appearing plugs. Imagine how confusing that was! Anyway, I'm anxious to see what happens when the ignition is straigtened out. I don't think that will be the end of the problems, but I think Argneist will achieve a quantum leap in engine performance. I think once the engine fires on all 6, then a 100-200 mi drive is in order to give a new set of plugs a read. Then if the plugs aren't consistent with each other, it's probably time to pull the fuel rail again (sorry, Argneist!) and spray some fuel into 6 juice glasses. BTW, Argneist, the plug read will be a lot more meaningful if you ADJUST YOUR VALVES! You can do that while waiting for ignition parts to come in!

Yoshi, I'm guessing the click you're hearing is not the starter solenoid. It's probably the ignition relay or something. Does the click happen when you switch the key to the "on" position, or do you have to turn all the way to "start" to get the click? Is there any way you can have a friend turn the key, while you lean over your engine and listen to make certain the sound is coming from the starter? You might also want to put your hand on the starter's solenoid (the smaller protrusion on the starter with the spade connector on it -- the only connection with a little wire) and see if you can feel the solenoid click. If this happens, your starter is still suspect. The wire test: Yes, pull off the only little wire on the starter. Clip a small wire to that same connector on the starter, and touch the other end to the (+) post of the battery. Don't touch any part of the wire that isn't insulated. Make certain your transmission is in neutral. When you touch the wire to the (+) post, the starter should crank. Alternative to the wire test: Put a multimeter in the V mode at an appropriate scale for measuring 12V. Pull the little wire from your starter, and touch the (+) probe of a multimeter to it. Touch the (-) probe to ground. Have a friend turn the key to start. The meter should read approx 12V. If the starter doesn't turn when this same small wire delivers that 12V to it, then you've got a starter problem. This assumes your battery cables are as good as you believe them to be. (I don't see new cables in your pics, so I don't know which ones you replaced.) BTW, you can indeed find separate starter solenoids, but they're for old Fords and such. I doubt you can buy a separate solenoid for your 280Z, but I might be wrong. I've just never seen one.

Replace the thermotime switch? Dunno... Probably not. I think I'd do more diagnosis. I'd keep a multimeter and a can of starter fluid with me and have an action plan for what to measure/check when the engine dies next. Practice these measurements so that you can work quickly and methodically. First thing, use your method of choice to determine whether your ignition is generating a spark. Second, pull the small vacuum line off of the intake manifold near your brake booster vacuum line. Remember the small line that goes to the vacuum valves? The line that you fixed? That one. Pull the small hose off, and shoot some starter fluid into the hole. Then try starting the engine. Does it fire up for a second or two, but then not run after that? Then the problem is probably a failure of the system to deliver fuel. Keep the the spring clip removed from your cold start injector, so that you can pull the plug easily. When your engine dies, try pulling the cold start injector plug and seeing if you can fire up your engine. If you can, then you probably have a faulty thermotime switch. I'd have the trim over the driver kick panel removed, so that you can easily get to the big ECU connector. Write down on a card which contacts to probe to test for continuity in the coolant temp sensor. when the engine dies, TURN OFF THE IGNITION SWITCH FIRST, remove the ECU connector, and take that resistance measurement ASAP. If you have no continuity or have a dead short, that's your problem. If it checks normally, plug your ECU connector back in and try firing up your engine. If your engine fires up, then you can't really conclude much. If it DOESN'T fire up, even when the coolant temp sensor checks normal, the problem is not your coolant temp sensor. Also make sure you have power to the ECU connector when the ignition switch is on. Note again: BE CERTAIN THE IGNITION SWITCH IS OFF WHENEVER DISCONNECTING OR RECONNECTING THE ECU CONNECTOR FROM THE ECU! Try jiggling connectors to see if that gets your engine going again. Try disconnecting and reconnecting your ECU connector -- but again, ONLY WITH THE IGNITION SWITCH OFF! Also try jiggling the big connector on the bottom of the air flow meter. That's all that occurs to me right now. I'm sure others will chip in. My point is, prepare yourself to conduct a lot of essential tests very quickly and efficiently, so that next time the engine dies, you can rule lots of potential issues out. The alternative approach is to just start replacing things you suspect MIGHT be at fault. You can simultaneously go broke and lose your sanity doing that.

Another vote for pulling the radiator and dropping it at a shop for rodding out and cleaning. Also put in a 180 thermostat. That's not your problem, but you need one. Finally, it's unlikely a bad water pump would be your problem. The vanes would have had to rust away, which would be unlikely. Prestone radiator flush does little or nothing to help a corroded radiator.

I have an MSD Blaster 2 coil on my system. Nice coil, but I don't see it listed at AZ. I see a Blaster 3 coil for $47, but I'm unfamiliar with the Blaster 3. I'm guessing it's an improved version of the Blaster 2? Mine is a bit smaller than the OEM coil. I had to put a wrap of rubber innertube around the coil to mount it in the OEM bracket. You can also buy an MSD brand bracket. You should be able to find these at your local parts store. I think you have to order NGK wires. I haven't found them locally in my area. Here's an auction for a set on Ebay: http://cgi.ebay.com/ebaymotors/NGK-8105-Spark-Plug-Wires-Set-_W0QQcmdZViewItemQQfitsZModelQ3a280Q5AQQhashZitem3a64cf3b36QQitemZ250799405878QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories Advance Auto parts in my area carries the NGK plugs. I would think any cap and rotor would be fine -- available at an auto parts store of your choice. Your local parts store might not have all items in stock, but it would probably take no more than 1 day to get them in from a nearby warehouse. Keep in mind there is still one item in your system that could be bad -- your ignition module. Try the rest, and see how your car runs. If you still have ignition problems, then consider either a replacement OEM ignition module or a GM HEI retrofit.

The solenoid is part of the starter, at least on the Z. I don't think you can replace just the solenoid. The whole starter, rebuilt, is about $70 at autozone, with a lifetime warranty. It's a cheap rebuild, but it's also easy to replace if it goes south. I'd remove the nut as Zed Head suggests. If that doesn't work, you can use a nut splitter or perhaps just saw/drill the nut off. (I think they'll still take it as a core.) And your last question: No, you haven't yet confirmed that you have a problem with the starter and not the ignition wiring. You really need to do the wire test for that. You MIGHT have a situation in which the starter wire (the little one) is shorted or has a bad connection. Or perhaps you have a fusible link that's out. Or perhaps your ignition switch is going bad. Or perhaps you have a bad cable or bad ground. There are a few possibilities that happen with some regularity to other Z owners. The only thing you're ruled out is that a weak battery is not to blame. To test the starter, you're going to have to touch a wire from the (+) of the battery to that little spade connector on the solenoid. If the starter works, then it's definitely something in your wiring. If it doesn't work, it could either be a bad starter or something in your wiring. (For instance, perhaps you have a bad battery cable.) Then you'll have to do some additional tests to figure out where the problem is. A multimeter will be invaluable for this. But considering that you have a stripped post, you need to address that situation first. If you're able, back off the nut using the method Zed Head suggested. If you find your starter is good, you might be able to replace the nut and use washers to space the nut onto a portion of the post that still has good threads. However, the easiest thing to do is to replace the starter and see if a new one works. Then again, I know $70 can be a lot to a student -- perhaps less so nowadays, compared to when I went to school.

... but don't forget to ask the protestant for his cloak too. It's sort of an ask for one, get the other free sort of deal, as I understand it. To the OP: Turn on your heater, and smell the hot air coming out of it. It might have that same strong smell. I suppose if you have enough of that smell flowing through the interior of the car and then to the exterior, you might smell it there too. If the smell is more than that, you might have a tiny radiator leak. How often do you change antifreeze? Old antifreeze loses its corrosion inhibitors and can leave your radiator, heater core, and engine internals susceptible to corrosion. That might be the source of small leaks.

n2deep, you fixed the vacuum lines to the heater/AC system that are used to open and close doors, stopcocks, etc. One of the lines pulls your idle up when the AC compressor comes on. I doubt any problem in this system would cause the symptoms you've described -- certainly nothing that would instantly kill your engine after it's been running well for a while. Lostxsoul, yes, I would think tapping on the thermo housing could trigger a malfunction with the thermotime switch too. I don't know whether that would be enough to kill an engine, though. I also question whether a bad thermotime switch would cause an engine to run for a while and then spontaneously die. My own theory is that tapping on the thermo housing caused the thermistor in the coolant temp sensor to open up, giving it an infinite resistance, signaling EXTREME cold, and triggering a very rich running condition that might kill the engine.

Perfect for that Shriner in your life!

Yes, Argneist, you will be punished! Adjust the valves! Grrrrrrr! That said, I think you'll see marked improvement when you straighten out your ignition. Your motor might not end up 100% right (or might), but I think you will see MAJOR improvement. This is what I'd replace, even without testing: Spark plugs (NGK B6ES-11) Plug wires if they're older than say 5 yr. or if you don't know their age. Use the NGK spiral wound silicone insulated wires, similar to the ones you have. Cap Rotor Once you've replaced all of these, try starting your engine and see how it idles. Readjust your idle speed if necessary. Check your engine vacuum. Listen to the exhaust. The exhaust puffs should be perfectly spaced. There should be nothing random about them. Put your timing light on the wire between your ignition coil and the center post of your distributor. There should be no missing flashes. Then check back with us. You might have other ignition components that need replacement, but the above should be replaced irregardless. Oh, and I think you've ruled out problems with the electrical firing of the injectors with your noid lights. That doesn't mean the injectors are necessarily in the clear, though. Your 4-6 injectors might be clogged or stuck. But for now, the smoking gun seems to be elsewhere. Good job, BTW! Well done!

Well, a stock Z's acceleration might be slightly disappointing by today's standards. After all, there are now stock configurations of automobiles that boast 500+ hp! The modern-day hunger for power is insane, even by 50's and 60's standards. That said, a Z isn't meant to race Corvettes. A Corvette can easily take a Z on a straight road. Top-end speed might be different, though. I think A Z can top 150 or 160 mph. I don't know what a vette will do. Where the Z will take the vette is on twisty/curvy roads. The vette has a very light body and a very heavy engine, with most of its weight on the front wheels. It's not a particularly nimble machine. The Z is VERY nimble, by comparison. I think a Z should EASILY take a '49 bug under any driving conditions, perhaps with the exception of fording a river. (Bugs float.) What sort of performance should you expect? Well, I like to do a brief Italian tuneup on my Z everytime I take it out -- one quick, WOT acceleration from stop to some reasonably fast speed, revving the engine somewhat high-ish (e.g. 5k). I do this just to blow the cobwebs out. When I do this, my SO says it's like being in a rocket ship. It's not as fast as our BMW Z3 was, but it's faster than our Miata. You should get around 160 hp from your engine, give or take. A bug, by comparison, has around a 50 hp engine and about 2/3 the weight. At the Z's weight, it would be matched to the bug in horsepower if it had 75 hp under the hood -- or if it were running on about 3 cylinders.

Oh, and didn't see your last post. Yes, clean any connectors... I shall return!

Argneist, I've got a bit on my plate this evening, but I'll research these things later. I'm pretty sure the voltages you show ARE battery voltages, not voltages from the ECU. (The ECU is unplugged, right?) It's been a while since I've run these tests and looked at the schematics. What is your battery voltage, BTW? The air regulator resistance is about right. It has a heater coil inside it that heats the bimetal coil that closes down the air flow. I'd be interested in a few measurements that might or might not be in the EFI Bible. Anyway, later... Meanwhile, I have to buy lumber and nails for some work tomorrow.

Bruce, I think it depends. The PO of my Z had his maintenance done by the local dealer and was on a first-name basis with the mechanic. I talked with the mechanic on the phone once and discussed the fuel pump check valve. He told me where I could probably find one and even rattled off the part number for memory. This is just to say there are sometimes old-timers on staff at these dealerships. It's not a common thing, but sometimes it happens.

Just measure it with a digital multimeter -- cheap, available at your local radio shack or auto parts store.

Yeah, I was thinking about the banking too. It would be "too easy" if it were 1 entire bank. Then you'd almost know where the problem is (that one wire from the ECU feeding the one bank). However, I suspect it's an accumulation of bad connections. It's a happy coincidence that you're running off of the front half of your engine, because that leaves you with a detonation every other cycle, resulting in a relatively smooth running condition -- at least smoother than any of the alternatives. (The firing order is 153624, as I recall.) Funny, that!