Captain Obvious

I'd be interested in hearing if those sockets work as well. I was messing around with mine the other day because they're corroded and had gone intermittent. I cleaned them up enough to work, but I'm not sure how long they're going to last. Would be nice to have new sockets back there. I guess my other option would be to pull them out and send them out for plating, but it would be much cheaper to replace with something like what you pictured.

Yeah, in theory it should be too warm for the CSV, but you're right, it certainly seems like it wants more fuel.

I'm one of the people who has disabled their cold start system. I removed the connectors to both my CSV and my thermotime switch a couple years ago and don't really miss it. In the cooler months, I do notice a slightly longer crank time the first crank of the day, but it's not like yours. And in the warmer months, I don't notice any change at all which makes sense based on the temp at which the thermotime is supposed to open. At your current ambient temps, your thermotime should be open 24-7 as well. I mean, I completely understand why rcb280z is suggesting the cold start system stuff... It sure looks and sounds like it wants more fuel. But if it's 85 ambient, you shouldn't be expecting the CSV to actuate anyway. My engine doesn't need any additional fuel at 85 ambient and it doesn't take me 2-3 tries to get mine to start. You've got something else going on... Have you checked for vacuum leaks? Search here at the site for "yogurt cup". Have you put a vacuum gauge on it when it's running? Here's some common areas of concern: Hole in your rubber PCV tube? Leaking intake manifold?Poor seal around your dip stick or oil fill cap? Cracks in your AFM boots?Malfunctioning CARB can valve?

Haha! And I just saw Zed Head's guru list. I'm no guru, but I'm honored to be even mentioned in the same sentence with such good company! Not sure I can handle the pressure.....

Not unexpected. Makes me think that the 6-7 volts you measured the other day was a function of the update rate of your digital voltmeter. Some voltmeters have an update rate of one second or more and that makes quick measurements like this impossible. If you got 10-11 volts (while cranking) delivered at the starter end of the big cables, then I think you're cables and battery are fine.

Belay that order... There is no link between the water temp sensor and the cold start valve. If you unplug the water temp sensor it will run pig rich. You might get it to fire off faster because the ECU will stuff in a whole lot more fuel due to the cold temperature it perceives, but that huge amount of extra fuel will drown the engine after it starts. Problem is your car intermittently stumbles on the start. If you pull the water temp sensor, it is going to run like crap, but you won't know exactly why it's running like crap. You won't know if it's only because the water temp sensor is disconnected or if it's the combination of the temp sensor being disconnected in addition to what has been causing your start stumble from before. About the only thing you could do WRT to the temp sensor is for you to pull the temp sensor connector and have someone else (preferably in pajamas) crank the engine. Then the instant it fires off, put the temp sensor back in place while being careful that you don't get your hand into the fan. Then if it starts great with the temp sensor disconnected, was it because the temp sensor was off, or was it simply one of those times when your car started just fine? How many days is your helper willing to run that test?

Jacob, Do you know a lot about cars? If not, you will. How's the underside look? That's the part that I worry about the most. I can fix just about anything else...

Thanks guys for the info and pics. I gotta see a pic of this fuse puller thing you guys are talking about. Makes me wonder now if I have a spot for that too. Siteunseen, nice card!

And reading back a little, I'm guessing the reason we're talking about battery cables at all is this: I'm not sure what you meant by "terminals". Are you measuring where the two large battery cables connect to the starter (One on the starter solenoid and one on the mounting bolt that holds the starter to the engine)? Or are you measuring on the two threaded posts sticking out of the starter solenoid?

Listening to the speed at which the starter cranks the motor over doesn't lead me to believe there's a problem with the battery cables or the starter. It sounds like a healthy typical speed spin. The battery and cables "sound" fine to me. (If I can legally do that...)

I'm sure I saw some pic of spare fuses in those holders somewhere, but I've looked twice now and I just can't find it. Driving me nuts...

Your Z has a place for a fuse puller as well as spare fuses? You got a pic?

I know I've seen pictures or sketches of those spare fuse locations in the past, but I went through all the FSM's and Owner's Manuals I have and I couldn't find them (it?). Do you think you've ever seen mention of those spare locations in any of the documentation? Do they talk about them or show a pic of them in use in your 71 Owner's Manual? I had wanted to post a snippet from the documentation as well when I started this thread, but I just can't find the reference I (think I) had seen before.

Don't know if this is old hat or not, but I was doing some poking around with my fuse block and discovered that there are holes at the bottom designed to hold spare fuses. Might be different for other years, but mine is a 77. If you look along the bottom edge of the fuse block, there is a row of holes for the spares. Here's a pic showing a couple spares already in the holes and I'm inserting another into a still empty location:

I don't know the current temps in IA, but here's something to try... Disconnect the electrical connector from your cold start valve. You might be flooding your engine while cranking which might be making it hard to start. And since it's temperature dependent, the times it starts OK might be a degree or two warmer. Warm enough to disable the cold start valve? If your start stumble goes away with the CSV disconnected, that might be a clue. Or, on the other hand, if it now does it ALL the time, that might be a clue as well. I know it's the shotgun approach, but it's free, easy and reversible.

Gotcha. So Rockauto has phantom stock. Well I don't know what's wrong with your existing wheel cylinders, but I think they're all the same internal bore (7/8 inch). If your external dust boots are OK and the problem is the internal piston seal, maybe the piston seal from the newer 72-76 rebuild kits would still work for your older cylinder? There really isn't much else in the kits beyond the seal, dust boot, and bleed nipple cap, right? Is the rubber boot to the backing plate included and is it the same one for both first and second designs?

Mario, Yes, the wire colors came from the wiring diagram in the FSM. And remember that it's just a theory. I'd be happy to be proven wrong. I'd also be interested to hear if any other 78 owners have seen similar behavior. I guess unless they had a pressure gauge installed, they may never know. After watching your last video, I don't see anything wrong with either the fuel pump or the fuel pressure regulator. They both appear to be working fine. Yes. there is a check valve back at the fuel pump, but that's not what is causing your starting issues. It might be what is causing your eventual loss of fuel line pressure, but you showed that your starting stumble occurs even after you have primed the fuel lines. Your start stumble is not caused by low fuel pressure. So while it might be a good idea to chase your fuel line leak down at some point in the future, I don't think you need to do that now. It's not that big of an issue.

I have a theory about the short "priming" pulse to the fuel pump in the 78 Z... When you start turning the key to start the car and you get to ACC position, the wires to the fuel pump control relay have the following voltages on them: Black/Yel - No connection to anything. (Will go hot in START, but we haven't gotten to START yet.) Yellow/Blk - Connected to ground through the oil pressure sender. Should have been that way since before you put the key in the ignition. Blue - Connected to +12 through the CHG lamp and the coil of the brake warning relay. White/Blk (input side) - No connection to anything. White/Blk (output side) - Connected to the White/Blk input side wire, but since that's not connected to anything, the output side doesn't get any power. The instant you turn the key to ON, the wires to the fuel pump control relay have the following voltages on them: Black/Yel - Still no connection to anything. (Will go hot in START, but we haven't gotten to START yet.) Yellow/Blk - Connected to ground through the oil pressure sender. Should have been that way since before you put the key in the ignition. Blue - Pulled low through the alternator to essentially ground. White/Blk (input side) - Connected to +12 through the ignition relay. White/black (output side) - Now here's where it get's tricky... The two relays built into the fuel pump control relay will change positions, but that doesn't happen instantaneously. Before the key is turned to ON, the relay is in such a position that the input WHT/BLK is connected to the output WHT/BLK. And when the key hits the ON position and the ignition relay pulls in, and for a brief time the output WHT/BLK will still be connected to the input WHT/BLK and it could temporarily energize the fuel pump relay sending power to the fuel pump. So when the key hits the ON position, the alternator controlled side of the fuel pump control relay will pull in. When this side pulls in, it makes the connection that pulls in the OTHER side of the fuel pump control relay. The pulling in of those two relays takes a little time and maybe that's the brief instant the fuel pump gets a short shot of power. It's not supposed to happen, but I can definitely see it happening in reality. Especially if the contacts in the oil pressure switch are starting to get a little dirty and don't provide as strong of a connection to ground as it should. That could delay the pull in of the second side of the fuel pump control relay causing a longer pulse to the fuel pump.

I'm a little confused as to what it is that you're looking to buy. I assume the answers are obvious, but it's my job... If you're looking for rebuild kits for your 70-71 cylinders Rockauto lists two options. Rockauto, however, does not list replacement wheel cylinders for 70-71. But your original post makes it sound like you're wanting to rebuild your original cylinders, not replace. And for the 72-76 cylinders, Rockauto lists both replacement cylinders AND rebuild kits. So exactly what is it that you're looking for?

I got some pics of my 77 style brake warning relay. Four position connector, three populated positions. Here it is in it's natural habitat: I took it out of the car and discovered that I had left myself a note from the last time I was in there: Pull the guts out of the metal case. Note the black crispy areas on the coil windings: Looking it over, I was actually able to see the break in the coil wire: Also, being the curious type, I measured the resistance of (what is left of) the coil and I got 10 Ohms, which is way too low. It does, however explain the balled up melted blobs of copper on the ends of the magnet wires where the wire melted back... Tells me that it didn't go peacefully. When this thing went open circuit, it went with gusto! So with all the above info, here's my forensic analysis... The coil ran hot from day one and eventually degraded the varnish insulation between coil windings until it shorted internally somewhere. It may have gone from it's original starting resistance is to the current level of 10 Ohms in one shot, or it may have shorted out just a couple turns initially which would reduce the coil resistance, draw more current, and get even hotter (avalanching to it's ultimate death). In any event, eventually one coil turn shorted to another and greatly reduced the coil resistance to the current 10 Ohms. For a short bright instant, the coil drew over an amp until POP, the wire acted like a fuse and vaporized a quarter inch of copper. I'm comfortable not using it at all. I use my parking brake religiously and it also lights the brake lamp on the dash. In other words, my brake bulb gets tested even though I don't have the relay installed.

Sampler flights!! I'm in!

I'm always grabbing stuff I shouldn't be....

Thanks for the additional info. I haven't looked at the MSDS sheets for any of those products, but I would have expected them to be more nebulous. I would have expected the usual "proprietary blend of petroleum distillates". Some of them get away with that and some don't.

And one more thing... At 100 Ohms coil resistance, that wrecking yard relay will draw less than half what your original is pulling. A little over 1 Watt being dissipated inside the case of that one compared to close to 4 W for your original. I know 4 Watts doesn't sound like a lot, but put an empty soup can over a 4 W nightlight plugged into the wall for an hour. Then pull the can off and grab ahold of the bulb.

Oh yeah, I forgot to talk about your current relay. It certainly looks like a water line on the relay, but what has me confused is that it doesn't look level. So unless the car was parked on a very steep slope or the relay wasn't bolted into position and was hanging at some off angle by the wires, it may not be a water line? Is that simply a trick of the surrounding reference points and the rust line IS actually level? And I don't think that submerging it would really prevent it from working. The resistance of water is way higher than copper and the vast majority of the currents down there would still go where they were supposed to even while submerged. Not to say I would recommend it, but just saying I don't think that would kill it right away. I think a mechanical failure would occur before an electrical one. In other words, I think the internals would rust up solid before the coil would fail. That's definitely gruesome though. Thanks for sharing!