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I have several questions regarding the precise fuel pressure both of the 3 screws round SU CARBS on my 240z will tolerate as i am pushing the fuel through an AIRTEX 8012S which is rated 5 to 9 PSI: 1. Should i measure the fuel pressure plugging a "T" before the front carburetor? 2. Should the pressure read no more tan 4.3 psi? 3. What if the pressure reads more than this limit but does not show any spill out of the fuel bowls? Will i need to open both fuel bowls and reset the level. THis was done by Ztherapy in 2014 and i would not like to mess with it.

Hi all: First post, so go easy on me. I don't own a Z yet. But I'm going to look at one (a '77 280) that may become available for sale. Current owner says he let the car sit for a couple of years, and the fuel went bad. He drained the tank and refilled with good gas. The car will start, but won't run for long before shutting off. He says it starts right back up and then dies again. He and I discussed, and theorize that there is crud (probably rust) in the tank getting sucked into the tank outlet screen and clogging it. If that theory is right, I assume the tank needs to be cleaned out, and maybe coated to prevent rust. I'm only beginning to learn about these cars. So I don't know what else to look for. It seems that the fuel pump works, and the engine otherwise has spark, or it wouldn't start at all. I'm going to look at the car on Saturday. I plan to take a fuel pressure gauge, starting fluid and a spare fuel filter. What else could be wrong that can be tested without too much trouble? I'm hoping for an easy fix if he decides to sell it to me. Thanks in advance, John.

Hi all, new guy here. I will take this opportunity to introduce myself and my car. About me My name is Mario, I live in Cedar Rapids, IA. I'm in my low 30s (for those who care), I like to work on cars, but I don't have a whole lot of detailed experience, however I'm very willing to learn. In early April igot the car (I wasn't necessarily looking for one, it found me). I've knew about 2X0Z for a while (my father in-law has two of 240Z sitting in his backyard rusting away ) but when this deal came I could not refuse. About the car 1978 280Z, 59,XXX miles when I got it. Original, survival (I have all the original paper work including signed contract from the dealer and window sticker). Never saw snow, rarely any rain. Previous owner had it for over 25 years and drove it maybe a 1000 miles a year. Always garaged. Few things he did to car: lower suspension with Tokico springs and adjustable shocks, big brake kit upfront, SS brake lines,cold air intake, newer spark plug wires, 2.5" exhaust form MSA, including down pipe and all the way to turbo muffler. Other than that all was stock, including all the engine gaskets! What I did when I got the car Replaced the fluids: engine oil and filter, rear diff, MT oil, coolant. replaced the spark plugs with with the stock NGK ones, replaced fuel filter, distributor cap and the rotor, replaced battery cables, installed new 16x8, 0 ofset XXR513 black/silver wheels that came with the purchase. The issue I have hard time starting the car after it sits for a while (for example a day at work). The car did not have this issue when I first got it, but slowly it developed it. One point to mention is that it started BEFORE I did any part replacement under the hood. Here is the link to a youtube video of wha the car does. Sometimes it is more sever, sometimes it is less sever: One additional point to mention is that the RPMs are typically low for "cool start". I would expect the RPMs to sit around 900-1000 when the engine is warming up and slowly come down to 700-800 rpms. It's as if the engine does not recognize the "cool start" and perhaps does not go into fuel enrichment period.The starting issue is there regardless of the outside temperature. It could be 85 or 60 degrees, still acts the same. Based on what I noticed this morning when I sarted the engine I'm thinking it has something to do with the air delivery. Right after I started the car (RPMs were hovering around 700) I went in and unplugged the vac hose between intake manifold and fuel pressure regulator. As soon as I unplugged it at the FPR and left it opened (therefore providing more air to the system), the engine reved up to around 800-900rpm. When I plugged the vac hose with my finger engine would drop rpms. After few minutes of running, this drop and rise of rpms was much lesser, if any at all. Here is what I did for troubleshooting so far I do have EFI bible and the Service Manual and I actually have performed quite a bit troubleshooting in the cold start department: replaced water temp sensor as well as water temp sensor connector, cleaned thermotime switch and replaced its electrical connector. I performed continuity/resistance/voltage tests as described in Service Manual at the ECU for water temp sensor, themotime switch, Cold Start Valve, and Auxiliary Air Recirculating valve. All checked out OK, unless I misinterpreted the results. I pulled out CSV, cleaned it externally and cleaned its electrical connector. I pulled the AAR valve and made sure that the internal flap was moving freely. I took out Air Flow Meter and made sure the flap was moving freely. I wiped it inside. Having AFM out gave me inside look at the throttle body, so I sprayed some electrical connector cleaner and wiped it clean (there was actually quite a bit black gunk that came out)...the starting problem persists.The fuel pressure is not maintained in my system. I installed inline fuel pressure gauge right after the fuel filter. The pressure drops to 0 after few hours of car being off. However, before I crank the car I prime the fuel pump by turning ignition to ON/OFF position 4-5 times, until I see that pressure gauge reads around 31 psi. Even then I still get the problem. ...I started to run out of ideas. ​What else can it be? One of the comments in my youtube video says it could be a vapor lock. If so, what could cause this vapor lock? Beside this starting issue I believe car drives well (I say believe, because I have never driven a Z so I don't have a benchmark to compare to). It feels like it pulls all the way through the RPM range. The only other thing I have noticed is that when I drive it harder I get slight afterfire when up shifting 1-->2 and 2-->3 gear. Help...

New on fuel system: - Fuel Hoses - Vapor Hoses - Pressure Regulator - Fuel Pump - Clean tank - Rebuilt injectors Vacuum is 19. When driving the car, the fuel pressure will increase to 36 psi at full throttle. It is 28 psi when idling and sounds like it's running lean. Pinching the return fuel hose to the tank increases the fuel pressure to 52 psi. Removing the vacuum hose to the Pressure Regulator ups the pressure to 36 psi. Also ran the car out of a gallon gas tank and still 28 psi idle. Factory Service Manual says it should be 36 psi. Any ideas on getting it to 36 psi? Thanks.

I am not actually the owner of a 280, I am the owner of two 1977 710 wagons. One is a parts car that was my first datsun, a rusty mechanic owned and duck taped beauty. It ran before I started using it for parts for a perfectly kept garaged wagon I found about a year later. If anyone knows of a forum better suited for 710's please let me know. When I search on line I keep getting directed to this forum, so I thought I would give it a shot, not sure if anyone here can help me. Me and my second wagon had a wonderful time for the first two years. Until gas was leaking profusely out of the base of the carburator. I decided to get the carb rebuilt rather than buy a new carburator, as a new carb would mean many modifications (origional carb no longer available). The carb was rebuilt, but the car was now having trouble accelerating. It never had this problem before. I am told that the newly cleaned carb can effect everything else. It struggled all the way to 60km (35m), stubornly stayed at 60km (35m), and than it seemed to shift and it accelerated fine after that, although did not sound as good as I remember. Every time I slowed down this process happened all over again. I took it to a mechanic to adjust the timing and choke in case me and my helper did it wrong. He said it was still running ruff, and I gave him the go ahead to replace the points and condenser and to adjust the valves. The car still has the same problem it did before the timing and choke was adjusted by the mechanic, it does not want to accelerate, until it is able to pass 60km (35m) and than it accelerates fine. The one thing that did change after taking it to the mechanic, is once it passes 60km (35m), it accelerates at a rate like I never knew a 40 year old car could. I am attributing this to the valve adjustment. oh yeah and there is black smoke sometimes. again a post carb problem. So this is where I am at now, my manual spans many models and years and I am having difficulty identifying where the parts are that I need to check. Info on the interenet is inconclusive. This forum deals with 280's. I have learned here though that I need to check for a vacuum leak and the fuel pressure. I am choosing to assume at this point that the EGR and relays are working fine until I eliminate the more common causes. I do not think my car has a throttle position switch (?). I would like to do the yogurt cup test, but I don't know where the Throttle Body is, do 710's have one? I am not a mechanic and this is my first car ever worked on. Without 77 specific manual I am never sure if the parts even exist on my car. If someone could explain where the intake and throttle body are in relation to parts that I know (carb, alternator, rad, motor) that would be great. I am an artist, so as a visual person pictures and videos would really, really help. If you are going to post a close up of parts, please also take a zoomed out photo. The engine is a L20B. Thanks, I love driving this car. I can't imagine driving anything other than a datsun.

Hi folks, I am a new Z owner (1972), and looking forward to refreshing/restoring this beautiful car. She currently runs OK, but could be better. I am, by no means, a great mechanic, but it appears that there are plenty of helpful folks in this forum. One of the previous owners of this car installed a CR PRO/FUEL adjustable pressure regulator downstream of the fuel pump, prior to the carbs. It is set on 4.5 (I assume this means 4.5 psi). I am not sure of the need for this fuel pressure regulator. I have read many complimentary comments on Z-Therapy's work in refurbishing the dual SUs, so I am planning to take that route. If the carbs are rebuilt/balanced, have any of you had the need for such a fuel pressure regulator? Should I be concerned about the fuel pump? I suppose I could easily remove the regulator to see how she runs. Any comments on this aftermarket piece would be appreciated. Thanks, Steve

I need some suggestions of what to try next on my 74 260Z that starts fine but has little to NO power on the road. I have working on fixing the issue for 10 solid days and have ran out of ideas. Quick history - I finished restoring and finally started the car on Dec 14. The first drive was 12/23/11 and she did great. Drove her almost 400 miles over a few days without incident. Plenty of power and fun as hell to drive. Only twice in the first week did she kinda studder on take-off. Didn't think much of it until on New Year's day she almost stranded us 30 miles from home. Started making a different engine sound (a "bauhhhh" ipo a "brrrhhh") and sputtering real bad. Gimped home at 40mph and much slower going up hills but made it home. After 10 days of trying any and everything I think it could be, exactly same as it was. I need some new suggestions. She starts fine. Idles OK even though the RPM's fluctuate some. Just zero power. Here's what I've tried: Fuel: 1. New filter near mech FP, new filter near elec FP, neither were real dirty but replaced anyway. 2. Confirmed power to elec FP while running w/ test light wired into trunk, getting 12V. 3. Re-tore carbs apart. Yes they are flat-tops. Front carb bowl was kinda dirty with rust-colored debris. Rear was clean. Rechecked float heights and installed new diaphragms/gaskets on both power valves. I had put a new kit (needle/seat and other gaskets during restoration but failed to do power valves. 4. Removed fuel lines and blew them out. Checked with empty Mason jar that I'm getting plenty of gas when starting and running. I haven't hooked up a pressure gauge in-line yet as some have suggested. 5. Removed and cleaned all spark plugs. Front 3 were dirty and appeared to be wet or fuel fouled. Ran same after reinstallation of clean plugs. 6. Checked both sides of exhaust manifold after running awhile (ouch) and both sides were hot. 7 Disconnect charcoal cannister and cracked fuel cap for venting. Ran the exact same. 8. Ran with mech FP removed from series but ran about the same. Began thinking electrical at this point. Electrical: 1. Coil is a Crane PS20 and is seeing 12V while running. Replaced with the old coil and ran the same way. 2. I am going to check the air gaps in the dizzy today and run a test on vacuum advance that many posts mention but was hoping someone else had other ideas. Before we start a whole series of "boat-anchor" discussion about the flat-tops, I personally think its something else. She ran great for 400 miles first and the weather here is cool and not causing vapor-locking. I do not run coolant to the flat-tops per suggestions that overheating can occur. Anticipated thanks.

I had the "hot start" problem return this fall. The fuel pressure also dissipates over a few hours after shut-off. The PO removed the stock fuel rail "trombone" pipes and replaced them with a single billet rail. There is a Summit Racing pressure guage on the rail. With engine started and running, there is approx. 29-30 psi. Without vacuum to the FPR- approx 36 psi. I knew that the loss of fuel pressure, over time, can be (a) leaking: - check valve in the fuel pump - cold start valve - FPR - injectors The pump is fairly new, so I added a Parker check valve down stream, between filter outlet and rail inlet. No change. The CSV was original, so I replaced it. No change. The FPR was for a '77-without the stock fuel pipes, there was a blocked off inlet. I found one online for $45, so I replaced it with a'78 model FPR. Tidier. No change. The injectors were original, though they had been refurbed/ flow-tested by an injector service in the last few years, the connectors were getting brittle, so I replaced with new- not reman- Bosch units. No change. The pressure still drops to zero after a few hours. So where else can the fuel go if it can't flow backwards to the tank/pump (check valve) and it can't return through the FPR and the CSV/ injectors are brand new? I'm stumped. The "hot start" issue- engine stumbles and seems to run rich for a few minutes after a 10-20 shutdown having come to full temperature (180) is slightly improved. Before the work done, it was a b*tch to start and keep running for several minutes. Now it starts okay ,just runs a little rough. So there is some improvement. The CTS/ thermotime switches are new, all connectors and grounds have been cleaned and protected ( Caig De-oxit/ dielectric grease, where appropriate). The AAR was removed by PO. Vacuum is within specs, AFM checks out (Atlantic Z bulletins). I welcome any suggestions/ thoughts. Thanks for reading.