Captain Obvious

OK, so the car is (was) an auto. Has a single point dizzy now, but had a dual point when it left the factory. To check if it's the thermo relay... The thermo relay has four wires, a green, two blacks, and a red with a black stripe. If it's got those four wires going to it, then it quacks like a duck.

Thanks Zed for the info. Your note about the supply line to the pump "will do more than drip when disconnected" is just the kind of thing I was looking out for. Thanks for that. It's stuff like that which I want to be prepared for. My pump is fine, it's just the check valve that's not working. I diagnosed that it's the check valve by clamping off the supply line between the filter and with a helper, killed the motor at the same instant. This left the rail pressurized, but shut off both the supply and the demand. With that line clamped shut, the rail held pressure, for some time at least. It was down in a few hours, but with the supply line from the pump open, my pressure falls off almost instantly. In other words... My FPR may be slowly leaking as well, but big fish first. :bulb:

Awesome! You are the man! However, my fine friend, I'm betting that you guessed wrong on the threads. I really doubt they are NPT threads. In fact, I'm betting the threads are not tapered, and are probably metric. I'm assuming the valve was sealed with a brass or copper crush washer threaded under the valve, right? If that's the case, then here's how my forensic analysis goes from the crime scene photos... With a major diameter of .390, they are M10, and with a thread pitch very close to, but slightly wider than 1/8 NPT (which is 27 TPI), I', guessing they are 1.0 mm pitch (which would be 25.4 TPI). So, I believe the valve uses a M10 x 1.00 thread on the pump end. Have you got a (known) M10x1.00 bolt that you could run into the pump to double check?

Thanks again for the input. I did some searching last night and I turned up some check valves that are threaded on one end and accept a rubber hose on the other, but the problem is that I have no idea if they are the correct threads or not. siteunseen, Could I trouble you to unthread the valve from your old pump and measure the diameter of the threaded portion? That should be enough info to at least identify which size of threads they are. That will probably rule out most of what I've found.

I believe that relay is specific to automatics and controls spark timing. Interesting, however, is that the FSM for 72 doesn't mention a dual point distributor in the EE section, but there are mentions of dual points for automatics elsewhere. For example, page EC-11 has a description of the dual point system and a picture of the relay that does the control. Also, on BE-1, there is a connection for the "Thermo Relay". So... Do you have a dual point distributor in your auto trans car? 73 and 74 had a full blown documented system, but it's looking like 72 was a transitional year? The parts were there, but the documentation hadn't caught up yet?

Thanks for the ideas guys. So a couple follow-up questions... If I DO decide to go in after the OEM check valve and pull it out of the pump to take a look at it, I know I'll drop a little gas in the process. But is it going to stop dripping or does it set up some kind of siphon out of the tank? In other words, is the fuel pump below the level of the pickup or does it suck uphill out of the tank to get to the pump? Anyone know what thread they used on the original check valve where it threaded into the fuel pump? Lastly... In the FSM they warn about running the tank completely dry because they say it's hard to get the pump primed again. For those who have been through a pump replacement, is it really hard to get fuel back to the pump or is this risk over exaggerated?

Been a while since I was inside the lock, but I believe that spring/rocker/pin assy has two functions. The first is to activate the "key in ignition" chime switch. The second is the hold and latch the steering wheel lock OFF once the key has been turned away from the "LOCK" position. The rear part of the bar catches a slot in the steering lock slide and holds it out of the way until the key is removed completely. So when removing the key, you aren't fighting the steering lock slide spring the whole time. It snaps into place when the last tip of the key finally leaves the lock. Problem is, however, I don't remember how the rest of the steering lock works, so I don't know if you would run into any problems at the other end of travel. In other words, I don't know if there would be any issues all the way around over at the "START" position. Why don't you just buy a replacement at a hardware store? Here's some pics that should help you find a suitable replacement or something close enough that you could modify it to work: And for good measure, here's how the "key in ignition" switch connects:

The check valve on my fuel pump doesn't hold. As soon as the pump stops, my pressure drops off. I'm thinking I could fix the one in the pump, or I could bail and switch to a stand alone check valve up in the engine compartment. I'm thinking that would make future repair/replace easier if I ever have to mess with it again. So, anyone got a reason why I shouldn't do that? Is there some reason that a check valve built into the pump is a better idea? Anyone got recommendations for a stand alone check valve they've used with good results?

Haha!! Heard THAT!! I made that mistake. I think I got the best reaction to be expected. "Well whatever... As long as you like it. Hey, what's that smell"? she says shouting over the exhaust and road noise.

Have you got a pic of that? (I know you do... You've got a pic of everything!) :paranoid:

I saw Phillip's message as soon as I finished mine and saw that he's got you covered. He should be able to hand carry a few of those for you (and him, I suspect). Excellent. And you're right about adapting the sight glasses from your anchors. They are designed to mount into a large flat surface, which doesn't exist on the round top bowl sides. You got a tig capable of aluminum? :pirate: But before you pull the trigger on a sight glass... Take a look at the other options at that web site. They offered straight threads as well, and I don't know which would be a better approach. If you're relying on pipe threads to provide both mechanical strength and hydraulic seal, I'd be wary about the small number of threads of engagement that you'll be able to get in the relatively thin wall of the bowl casting. I'm thinking that a straight thread and an O-ring might me a better alternative. Just something to think about. I've given it some thought in the past as sight glasses into the round tops has been a stalled project on my workbench for years, but never enough deep thought to make chips. Measure once, cut twice, I always say!

Haha! Yeah, that's the sight glass from a "boat anchor" flat top. Just one of the many improvements they made to the Cro-Magnon antiquated round top design. (Where's my hornet's nest smiley...?) Seems that what's old is new again? My pleasure JK. I've taken those sight glasses out before. They are real glass (I wouldn't use plexi for gasoline), and are pretty thick. They are sealed by one O-ring that gets squished up against the face of the glass disk when you tighten the screws. Use Buna-N (or Viton if you can find it). $102 shipping. That's rude. Would you like me to order some of those sight glasses for you and send them to you? The screw in types would probably be easier to mod into the round top bowls than the ones from the flat tops.

Yeah, too bad Datsun didn't include one. Oh wait... They did!! :bandit:

Too late, I guess, but I've got a full dash cap for sale... $50. :bulb: Unfortunately, I'm at the other end of the country: There are a couple other pics in the craigslist ad: Datsun 240Z 260Z 280Z Dash Pad Cap Cover Nissan

Was the front camber better before you did all the suspension work? In other words... Was this issue was always present, or is this a new development somehow caused by all the work you have done?

I can narrow it to 77-78. They're the only ones with the speaker holes there.

Yeah, that's one of the reasons I put up the picture as there are more than one U-joint and I wasn't sure which one (or both) you were having troubles with. That column I took apart in that pic is kinda laid out as it is installed in the car. Towards the top is the steering wheel, and towards the bottom is the rack. I cut up the top shaft (second part from the top) to use as a test piece for my wheel hub, but other than that, I've still got the rest of the parts if you need any of them. Don't know if this impacts your decision to wait, but... The shaft that connects to the rack AND the lower shaft inside the steering column can be both be removed without taking the column apart. In other words, both shafts that include U-joints are able to be replaced without disassembling the rack. (Unless I'm forgetting some detail, of course!) Now, I don't know if there exists enough room to draw the center shaft out of the bottom of the column while the column is still in the car (or if it hits the engine or something), but if there is enough room, it just slips in and out the bottom. So something to think about... Replacing those lower two shaft parts might not be as difficult as it sounds. The TOP shaft (the part that contacts the steering wheel) would be a pain because it requires complete disassembly of the column to get it out, but the other two? Not so much. Anyway, these parts don't fit my later design column so some (or all) of them are available to you for shipping plus a buck or two for packing material and gas to get to UPS. If you find that you can't get new and want used, let me know. Just remember that I'm not gonna keep them forever.

How convenient! I already had pics! This is what I have left, with the exception of the shaft in the upper right. Is what you need in here somewhere?

Mike, I harvested an older style steering column as part of my steering wheel project Let me see what I've got left...

You've already got one of those... It's called the throttle position switch. That's exactly what it does.

The top pic is a condenser that is supposed to be connected to the coil. It's function is to quiet ignition noise so the radio doesn't pick it up. You can find the condenser in the lower left hand corner of the wiring diagram. The other two wires? No idea. The previous owner could have been using them for anything. What does the other end inside the interior connect to? Anything?

Me too! And for the record... When I said the below: I meant "Two heads are better than one and I've got some diagnostic equipment and some spare parts we can try that would probably help. I can also provide the foot to keep the engine running while another set of hands can check things up in the engine compartment." I did not mean "My skills are better than yours."

Cool. Was this for actual money, or your senior project? If it was for $, who were you working for? Bosch? Audi? 3rd party contractor? When we meet, remind me to tell you a story about control loops and very high gas mileage. I'm not writing anything down because I'm not sure the NDA has expired yet, but I'll tell you in person. :tapemouth

I never trusted a thing Sweed said. I'd put my money on the Madam. Backing up a little... I'm not sure how to interpret your earlier post. Did you help program the digital EFI (which used a 6805 MCU as it's brain), or were you involved in the programming to create the 6805 processor itself? In other words, did you work on the internal architecture of the 6805 or were you using it as your target on your board? Either way, it's cool. But I just don't know how you really meant it.

I know some of the more complicated aftermarket electronic ignitions systems have programmable advance capabilities. I just didn't know if yours was one of those. I'm assuming if you don't know for sure, then it's not. Shotgun approach here... Have you got access to a stock ignition module? Is the wiring still intact enough for that? Man... Just so many variables. If you bring the car to my place, I promise in a weekend we'll have it licked!!