Dave WM

could be but that can be tested after you get it started (voltage reg) no need to order it, you maybe able to just clean up the points on the old on IF its a problem. If you charged the battery with a charger and its weak now, the I would suspect the battery. IF after you get it started and IF the battery voltage is not being maintained by the alter then

more confused than ever on exactly how that is supposed to work so its a two way check valve? I wonder why they want air to flow back into the tank? did the 78 have a sealed gas cap maybe? oh wait is says there is a vacuum relief valve right on the gas cap description. ugh.

ideally the gas jug should be above the pump. maybe a little longer lines and put the jug up on a box.

wow, ok so you start with do you have power at the fuse box.

oh and I assume you have checked for good grounds, chassis ground from neg term to battery post, good neg connection to starter, good body grounds everywhere else, like the one under the fuse link boxes etc....

talking about the fuse links that connects from the battery post directly to the ECU. If the headlights are dim and all the rest of the stuff like horn starter etc.. all exhibit low volt behavior, then I would suspect the battery, regardless of what the voltage tender says. You need to check the internal resistance of the battery, correct voltage means nothing CCA is what matters.

how do the headlights look? nice and bright? horn sound strong? heater fan? just stuff that pulls a lot of current. check the fuse link for corrosion (the one that connect the battery to the ECU).

sounds like bad battery cables. remove and clean the battery post and the cable connector.

or you could read the plugs, should give a decent idea of A/F mix. all a moot point it would seem. Your looking for an explanation without enough data to draw a conclusion from.

that whole section on the evap in the FSM is a bit confusing to read. The way I take it the gas cap has a check valve that lets air into the tank from the atmosphere, as the fuel is used up to prevent a vacuum in the tank. the vapor tank check valve and the canister and the vacuum lines are a way to siphon off the excess fumes from the gas tank. due to heating of gas tank and fumes from gasoline, if anything the plugged line would cause a build up in pressure in the gas tank and not a lack of fuel to the FI. I know it says otherwise (per your circled part of the FSM) but frankly that does not really make a lot of since. the vapor line check valve would never allow an influx of air to compensate for the use of fuel, incoming air has to be from the gas cap. the whole point of the gas cap/evap system is to close off the tank from the outside air, burn up gas vapor when the engine is running or trap it in the carbon canistor when the engine is off. I think the intern engineer may have written that part (or translated it ) of the FSM. Note how the diagram does not show a check valve but its discussed. Also of note there is a built in restriction new the carbon canister in the rubber line that connects to the hard line back to the vapor tank. I don't think is mentioned. I have no idea what its function is.

yes if you want it to work as designed, but you should also confirm the line is clear. Do you have the FSM? I suggest you read up on it carefully before replacing anymore parts. The only non OE part that most folks do in the single clear G3 fram on the inlet side of the pump to keep the trash out. There are plenty of parts that may or may not effect how the car runs (as opposed to how it was designed to run and meet EPA requirements of the day). Personally I don't know enough about how everything was engineered so I tend to try and leave it as stock as I can and work the issues as they present. Opinions vary so its really up to you on how far you want to go on modifications that will work. That being said I highly doubt it is the cause of the current problem. One last thing if you want to put it back, remember it is a check valve so it will be directional.

that was prob a check valve.

Prob would not hurt to check to see if that line is plug, mine was. IIRC I would get a pressure build up in there with the plugged line. Agree it would not effect operation. I think I had some odd fuel filling problems or something, really cant recall. Its on my to do list (nothing worked to clear the hose).

I maybe wrong here but that line with the dry filter looks like it goes to the carbon canister from the vapor tank by the filler nozzle. not sure why anyone would filter that. oops JSM beat me too it.

yikes! had to look that one up. OBD

Roger, wish I had paid more attention, would not have bothered I had realized he was not interested if fixing it. of course the easy answer is there is no easy answer on second thought, if you are going to have old cars that don't have all the ODB stuff, then the simple answer would be a lot of things could cause the problem and you have to diagnosis it to determine them using proper test procedures and keeping track of results.

Did I hear a compression check anywhere? when you are having problems you need to diagnosis and work the issue, not throw parts at it and hope for the best, or take random suggestions made based on limited info. I sometimes will throw out a suggestion but its often wrong due to my having to take a SWAG at the issue due to limited info. Therefore I would recommend: Compression check, fuel pressure, timing just for starters. Tune up consisting of fluids, filters (air oil gas). Oh and a check of valve lash, adj if needed, very easy to do on a Z. Next up would be some new plugs, drive the car several miles then pull them and read for clues on mixture and oil blow by. listen for a misfire if noted do a balance test to find the offending cylinder, work the problem from there, has to be compression/fuel/spark. Resolve and test again. There is a process to diagnosis, the FSM covers most of the problems you are likely to encounter. Common problems are poor fuel delivery due to plugged lines, and poor electrical connections on the FI. Sensors on critical for correct fuel/air mix, a reading of the plugs is a good start for this. forgot to mention, on the bypass as others have noted, if you have a problem with it, you need to correct. Test it to see if it is functioning as designed (added air flow during warm up) using the FSM as a guide. If its malfunctioning replace it. One other item would of course check the vacuum hoses since you mentioned a whistle noise. Vacuum leaks are bad. Make sure the distributer is advancing as designed (there I go with a SWAG).

and for gosh sake get fuel injector style hose clamps, I hope you are using fuel injector rated hose. Make sure you look closely for fuel leaks, there are a lot of places for that to happen. I see you have hose clamps on the vacuum line to the fuel regulator, that should not be required if you are using the correct vacuum line. You need to stop with the descriptions and start with all the test that have been described. One real quick test would be to dead head the pump. Disconnect the starter solenoid wire, clamp of the return line, turn the key to start, only do this for a couple seconds as the pressure will build very fast, if you have an after market pump you may see upwards of 90psi. this will quickly determine if the pump and tank are able to supply high pressures. The reason you want to only do this for a couple seconds is its very hard on the fuel hoses and connections (clamps). If you did NOT use fuel injector rated hose you will likely burst something from the pressure (non FI rated is about 50psi). those worm gear clamps have a way of eating into the hose. I good supply of FI clamps is at the local junkyard, just go to the import section and look around, tons of them and top quality, not the junk sold in the auto parts stores.

not sure what you are showing. but you have to have good gravity flow of fuel at least to the fuel pump. Make sure you have gas in the tank, disconnect the fuel line at the inlet to the pump, hold it down and gas should flow big time. Agree too many filters, a single G3 is more than enough. you should be able to hold it down and have gas flow out, if not the line is plugged or the tank does not have enough gas in it. put at least 5 gallons in right now.

he may be referring to the sock that is located in the tank on the fuel pickup. I don't understand how the various coatings work around that (or even if there is such a thing). I paid a bundle to get my tank done, guy cut it open sand blasted, removed sock, welded back up and re sealed with something, then painted outside. the guy that did my tank did mention the sock filter inside my tank (I did not see ) so I assume it really is in there. If I had my borescope back then I would have used it to confirm, but its all done now, no leaks and no fuel problems. I am not doubting others that have endorsed DIY with redkote or POR15 just giving you another actual example. IIRC the guy was one of those franchise fuel tank refurb. Not that that means anything, but they are nation wide. Of course the francise means nothing its all the skill of the guy doing the work. I did take my tank to a rad shop, they looked inside and said "red kote" and would not touch it. That's when I was referred to the other guy. He did say the cost was higher than normal due to all the various inner walls etc. on my tank. All the above is just FYI, there is no reason to go down tank refurb until you have CONFIRMED the tank is the problem. You have to things on the table to do first. several others have posted how to confirm the pump/electrical supply. that should be checked 1st before committing to any major tank overhauls. The hard wired pump and separate fuel can would be a start. think I said already but you should also do a flow test, plugged fuel filter and stuffy fuel lines. what kind of pump is installed now? does it have a screen on the inlet side?

Sealey VS168 Looks like it may work.

you clearly have issues with fuel pressure. start with a new fuel filter, try again then I would second ZH on breaking this down. Start with a 5 gallon can of gas, with a fill and return line, bypassing the tank completely. See if it still does it. You have to break the system down to: fuel tank (can of gas) fuel pump (new one if any doubt) electrical supply to said pump (volt meter on pump) fuel lines (check for ease of flow) fuel filter (just replace it) pressure regulator after all the above then pretty much has to be this test by seeing how well it works in a static environment then adj by applying a vacuum. I

yikes!, but its a dry heat

not soon enough for me, tired of the 100+ for months..

fuel injection means you need a gasket that fits the manifold and has provisions for fuel injectors. 280z gaskets are one size fits all from what I can tell. Hard to find a square port bit, I ended up using the one that has D shaped exhaust port holes and it worked fine so far. You might find the correct square gasket if you buy the package (has all the gaskets for head and manifolds as well as others) I don't know if they still make it.