Captain Obvious

As it should be. That's the second function of the spring and rocker bar I mentioned above. When the key is inserted and turned off "LOCK" for the first time, that rocker bar latches the locking mechamism out of the way until the key is completely removed. The snap you hear is when the rocker bar unlatches the lock mechanism and lets the lock snap into place. Glad they found it!

Zed Head, I'm not sure you missed anything... Mike says his five speed has two ears on the rear housing which according to this site (Differential Ratios) means that it is an early five speed from a Z: I've got two ears on mine as well, so I'm thinking that Mike and I have the same genre. So does that revelation do anything to the suggestions about what to do about clipping reverse on the way out?

Haha! Great... That's one of the ones that's on it's way to me! I bought one of those, and one of the Bosch units that's threaded on both ends thinking that I might be able to modify it to fit better. Sorry, but here's to hoping that your issue is somewhere else! :classic: To test the check valve on the supply side, clamp the line from the fuel filter TO the fuel rail. To test the FPR, clamp the return line FROM the fuel rail back to the tank. The OTHER line over by the fuel filter. If you clamp them both at the same time and you still lose pressure, then you've got a leaking injector, cold start valve, or are leaking fuel through the FPR into the vacuum control line connected to your intake manifold.

I'll be watching your progress with this as I frequently clip reverse coming out of 5th. I've been inside trannys in the past and it annoys the crap out of me that I do this when I so much know better. I don't know if a stiffer detent spring would fix it, but if it does help and is that easy to put in, that would be excellent! Zed Head, What do you mean by "feature"? Do you mean the feature of clipping reverse on your way from fifth to fourth? Or the feature of having an anemic detent?

Thanks for the tip. Solenoid valves are easy to find. Solenoid valves that are guaranteed to be compatible with gasoline (and ethanol) aren't so easy to find.

I've got a couple ebay check valves on order. Should be here soon, but in the meantime, I had another idea... Anyone have leads on a car that used an electrically controlled SOLENOID VALVE on the fuel supply? Something that electrically blocks or allows the flow of fuel through it based on an electrical signal. If something like that exists, I could easily wire that into the system such that it will only allow fuel flow when the engine needs it. I've seen devices like that used in the vapor recovery system, but I've not seen one used to actually control liquid flow. So, anyone ever seen such a device used for gasoline control?

Gotcha. Well if I get into mine and find that it can be repaired, I'll take some shots.

I would like to drop back just a little and double check something... A lot of 280's have hot start issues and it's usually fuel related. I know you said there's no spark when this problem is occurring, but are you positive, no question, absolutely know for sure that it's an electrical problem and not a fuel problem? Are you sure that the timing light while cranking is a good indication of spark? Did you try the timing light when it's NOT hot and get flash?

Thanks for that link. I don't know yet if I'll need to do the flexible line, but I've got no reason to believe that mine would be any different than anyone else's. I'll hopefully get to this project in the next week or so. I'll keep you posted.

Thanks TomoHawk. I just recently finished a radio install, so now I need a working antenna. Mine goes "up" sorta. I haven't tried to run it all the way up to the clutch slip. I don't trust it. It picks up enough stations to keep me occupied until I can take it out and give it the once over. When that time comes, I'll probably be back with questions about where you got your mast, etc.

Yeah, that's probably what I'll do to start. Get one of those and turn the barbs off. It'll either be that, or something from McMaster. They have brass bodied check valves with fluoroelastomer (Viton) seals for about the same price. They're likely higher quality than the ebay valves, but the only problem is that they are all NPT on both ends, so I'm back to more fittings and adapters and joints that can leak. If I had other stuff I needed from McMaster right now, it would be a no-brainer, but I don't think I need anything else from them at this time.

Here's the flanged one I was talking about. Here's an example on Amazon: NEW OEM MAZDA FUEL TANK CHECK VALVE : Amazon.com : Automotive Looks great, but at $56, it's pricy:

Haha! The results of your searching look very similar to the results of my searching! I don't like the barbs, but could get over it if that's all I can find. I could turn all the barbs off except the two at the tips, or I'm sure I could just use it as is if I'm not that energetic. Hadn't seen the one from the Alfa before. Looks as good as the Mazda, but I bet the case is made from unobtainium. I went to the local parts store and talked to them about Mazda check valves, and they couldn't find anything. Also couldn't find anything on Rock Auto. I'm trying to avoid joining that forum just to ask questions about valves. There was one more that I turned up that had hose nipples on both ends and a mounting tang with a single screw hole in it that was used to screw it to the fender well. I'll see if I can find that one again...

Forgot to address the 1587010532 valve... This valve is not a good choice for our application. Not specifically because it's threaded on both ends, but more so because it's designed to be used with a banjo fitting on the outlet side. Think "banjo connector onto the fuel rail". There are other check valves that are threaded on both ends that would be better choices because they are simple pass throughs. You could either screw a conversion fitting onto the outlet to convert to hose, or you could turn the outlet threads smooth on a lathe and clamp a hose where the threads used to be. All that said, I'm still thinking that a stand alone in-line valve up in the engine compartment would be a better idea. Not only for future serviceability, but because you could put it downstream of the filter. From what I've read in search, it's usually dirt from the tank that contaminates the original valve's seat and stops if from sealing. So why don't I jump on the generic Airtex valve that was suggested above? Because it's got too many leakable joints. I want something that's native hose and clamp connection. Something like this one mentioned in this thread on an RX7 forum: (FUEL) How To: Diagnose your fuel return line check valve - RX7Club.com

Haha! How about you send me your old one so I can see what I can do with it? If I can fix one, I should be able to fix two of them! I'm like this close to making a new one from scratch... :pirate:

Right. It's already been determined that the one on the left is correct... For a 240. But I've got a 280 and the antenna looks like the one on the right. I have no idea if it's factory or if a PO has replaced it some time in the past. What I'm trying to determine is... Is the one on the right correct for a 280? It's either factory, or both of us ended up with the exact same aftermarket unit? Certainly conceivable they're both aftermarket from the same company. I doubt there are too many mfgr's out there, right? Also conceivable that they're both factory 280 units.

Neat idea about the tubing over the jaws to protect the hose you are pinching. I used the same needle-nosed Vice Grips, but without the protective sheath. It worked, but it left a "soft spot" in the hose where it is now easier to squeeze than it used to be. Not really a problem though, because it's between the filter and the rail, and I'll be replacing that piece after I spend 100 fruitless hours messing with the check valve back at the tank and finally give up. You know... After I've spilled gas everywhere, got dirt in my eyes, and almost burned the garage to the ground. :paranoid:

I've got an antenna just like the one on the right in this pic. There are no Nissan or Datsun markings on it. Was it ever determined if the one on the right is from a later year or is it an aftermarket unit? Zombie thread resurrection... That's what "search" is for!!

Ummmm... Have you not seen my body of work? Thanks for the part numbers. I've seen lots of product offerings that have threads on both ends. I could easily turn off the threads on one end and set it up for tubing instead., but I would have to know what the threads are that go into the pump (and that's one of the reasons for my thread investigation above). Yeah, Napaonline is no fun. I don't like their website either.

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?