FastWoman

Thanks, Enrique, and sorry for the hijack!

OK, your fuel pressure is pretty close to correct on all measures. You need the vacuum input to your FPR. This maintains a constant pressure differential between the fuel rail and the intake manifold (the path through which the fuel is sprayed). If this differential doesn't remain constant, your EFI won't meter the fuel accurately. You'll be relatively lean on heavy throttle and relatively rich on cruising.

I'm a believer in synthetic blends. Synthetic oils have polar heads that stick nicely to metal. When you shut down your engine, this keeps some oil stuck to your parts, rather than drained away into the oil pan. Then when you re-start, there's something there to lubricate your engine until the oil pressure comes up. Starting is apparently when most engine wear occurs. I use a blend, BTW, because only SOME synthetic content is needed to achieve this benefit. That said, I've been running Chevron Delo in my Z, so as to clean up the BBQ grill that the PO sold me. I rather like the oil. Despite the fact it's formulated for a diesel engine, it has the right ZDDP and is high in detergent. I might start using 4 qts of Delo + a qt of Mobil 1, thus creating my own high-detergent, high-ZDDP synthetic blend. FAIW, I once really liked Castrol GTX for its detergent content. It DID keep my engine very clean. However, I've seen tests (can't remember where) in which Castrol GTX was by far the very worst motor oil tested. The test involved spinning a cylindrical surface (similar to a cam) in a bath of motor oil, and applying another stationary surface to it (similar to a flat tappet) under progressively increasing pressure until the surfaces scored/galled. I swore off Castrol GTX after seeing that test.

Enrique, what you describe for the 240 filler neck is very different from what I experienced with my '78 280, which I presume is attributable to some changes in design and materials. (I know my '75 from years ago had a HUGE filler neck, while my '78 has a much smaller one.) My filler neck appeared to be made of neoprene rubber. It looked brand new after I finished wiping it down with mineral spirits. It was supple and shiny. (Do you know whether they made filler necks in '78 out of neoprene?) For all I know, the PO had replaced the filler neck recently, but I don't find mention of it in his paperwork anywhere. I presume it is original. Anyway, I just re-used my old filler neck. I did attach it to the tank first, and it went effortlessly through the hole. I had someone else feed it onto the barb. I realize the fat filler neck of the '75 (same as the filler neck on the 240s?) might need to be installed differently, but I'm just sayin'... because someone with a '78 (or '77) reading this thread might want to know. ;-)

Don't get too discouraged! Instead, lean on other Z owners for support. It may take you a bit of work to get your Z straight, but you'll eventually get there. Along the way, you'll discover that these cars are really very simple machines -- even with fuel injection. I confess I don't know where the various grounds are for the EFI. The box itself is the only one I know. You can probably find this information in the Factory Service Manual, which you can download free from www.xenons30.com. Don't be afraid of the big connector on the ECU. All you need to know is to have the ignition OFF when you connect or disconnect it. There are a lot of tests you can perform on your EFI right from that connector, using nothing but a multimeter and info in your FSM. In my experience (2 Zs now), you can get your car straight by simply going through it from end to end, checking, verifying, and if necessary fixing everything as you go. This may seem like quite a lot of work, but everything on the Z is very easy to get to, and as I said, it's a very simple machine.

Well, my philosophy is that you should fix problems as you find them, even if they don't have anything to do with what you're trying to diagnose (i.e. your fuel pump not operating). It sounds to me like you have a lot of corroded connections. After decades in very hostile conditions underneath the hood, the electrical connectors deteriorate quite a lot. You'll probably find they're severely corroded. You may even find that the plastic connector bodies are very frail and crumbly. You can replace MOST of them with Bosch-type injector connectors, which you can buy from a vendor named f0rest on eBay: http://cgi.ebay.com/ebaymotors/injector-connector-kit-6pc-datsun-280z-280zx-300zx-/290452375892?pt=Motors_Car_Truck_Parts_Accessories&hash=item43a04f8954 The throttle position sensor connector can be grabbed off of several other models of wrecking yard cars. The AFM connector can just be cleaned up. (It doesn't get as much engine heat). You should simply spend time going through electrical connectors -- cleaning (DeOxit, lemon juice, WD-40), lubricating, and replacing if necessary. Add a bit of silicone dielectric grease when you re-make your connections. After you've examined and serviced every connector you can find, then take your measurements again.

Zed, I'm thinking siteunseen meant the 48 psi is static pressure -- a gauge at the end of the fuel line, with no outflow. (Is that what you mean, siteunseen?) Static pressure is supposed to be 45 psi or better, according to the FSM. If you're talking about 48 psi before the filter, with everything connected up and flowing, then yes, that's rather high.

Don't fret if there's a leak in your "evaporator tank" (fuel/air separator). Mine had a leak around one of its fittings, as evidenced by deteriorated paint. I took it to my local radiator shop, and they re-brazed the fitting. It cost me $20 and was as good as new. As for the source of the leak -- it could be almost anywhere. I'd recommend replacing all your hoses and checking the integrity of all your fittings.

A gauge on the vacuum! Hmmmm... Sounds like a good idea! :-) Your fuel pressure does seem a bit low. It's not EXTREMELY low, but your mix would be richened a bit if you were running at the spec pressure. The fact that your engine runs way better with the vacuum line disconnected from the FPR means that your engine is ordinarily running too lean. It might be running too rich with the vacuum unplugged, hence the fouling of your plugs (?). I suspect the calibration of our analog ECUs might have deteriorated on many/most of our cars, so your engine might not be exactly right even with spec fuel pressure, but it will be CLOSE. You might want to replace your stock FPR with an adjustable FPR -- a good one, such as made by Aeromotive, not a Chinese knockoff (been there, done that, don't recommend it). Then you can adjust your fuel pressure to tune your engine to the correct mixture. This is a solution I considered on my own Z, which was also running lean. Unfortunately I estimated that I'd have to run the fuel at around 55 psi to compensate for MY ECU's drift. My fuel pump was incapable of such pressures. Instead of running non-stock fuel pressure, I opted to alter my coolant temp sensor circuit resistance, which corrected the mixture problem. But if I could have solved it with fuel pressure, that's what I would have done!

Your pressure sounds normal. The differential between your revving and idling psi is sort of low, suggesting that your engine vacuum is low. Of course it's a bit hard to tell from a fuel pressure gauge. When screwing NPT-type fittings together, it's good to wrap the thread with teflon tape to lubricate and make a good seal. You might be able to take the gauge apart to fix the bent face. I think getting the right AFM on your car will be a good step forward!

That's a stumper! Is your AFM's vane moving freely, without binding? I know you say fingering it has no effect, but I'm grasping at straws here. Maybe you have a bad ground somewhere that becomes a problem when the engine is rocking? Is the ECU firmly bolted in? Question: If you accelerate briskly, create this problem, come down to an idle, and then just sit there (with no actuation of the accelerator pedal, no movement, etc.), does the problem resolve itself spontaneously after a couple of min? Or do you have to do something, like work the throttle, for the problem to resolve? What happens if you KEEP running the car briskly? Does it only run briskly for a short while, before it starts running badly?

... and remember that there are also a couple of enormous connectors on the main wiring harness, just on the inside of the passenger firewall. They can get a bit crusty, to the point that the large(ish) current demands of the fuel pump can cause arcing and burning of the contact (which lies in the path between the fuel pump relay and the fuel pump). Of course your relay would still click, even if that contact were bad.

Another vote for a trickle charger (battery tender)! This is the tortoise approach to charging your battery, but it will definitely get you there. Regarding your battery, a starting battery has very porous, sponge-like plates. That gives it more surface area and therefore more capacity for high current. When you substantially discharge the battery, your spongy lead erodes away until it crumbles. When you recharge the battery, much of your original plate material will still be sitting at the bottom of your battery, and your plates will be smaller. Thus your battery is permanently impaired.

Oh, man, I wish I could be there. Are you sure you want to do this in Nov/Dec? Springtime in the hill country would get ME all excited. I miss the endless fields of wildflowers. I'm not driving from Virginia to join y'all, but I'm just saying...

Very nice! :-) You do wonderful graphic work! And HEY, welcome to the community! Congrats on your 240! :-)

Sorry I haven't been around much. Hurricane Irene. Ron, Take a look at where the big wiring harness dives through the firewall on the passenger side of the engine compartment. You're going to need to find the two large connectors right on the other side of the firewall, just inches away. You'll need to remove a small, plastic trim piece to uncover the harness and connectors. The fuel pump contact is right in the corner position of one of those connectors.

AJM, that's easy. Smog is always worse close to the ground, hence the need to ground the smog pump. Duh!

There ya' go! FAIW, this is similar to the one I have: http://www.ebay.com/itm/1-8-NPT-AIR-PRESSURE-GAUGE-0-60-PSI-SIDE-MNT-1-5-FACE-/270698402269?pt=LH_DefaultDomain_0&hash=item3f06e1d1dd ... except mine is a 100 psi gauge with a 1/8" NPT thread. It's screwed into one of these: http://cgi.ebay.com/ebaymotors/Brass-Pipe-Tee-Female-T-Fitting-1-8-NPT-Thread-Air-Fuel-/260609617943?pt=Boat_Parts_Accessories_Gear&hash=item3cad8b3017 ... and two of these are also screwed into it: http://cgi.ebay.com/ebaymotors/Fuel-Hose-Barb-Fittings-1-8-NPT-x-5-16-Hose-Barb-/130454543600?pt=Boat_Parts_Accessories_Gear&hash=item1e5fb25cf0 I have to say the prices at my True Value hardware store are a lot better, though! If your fuel/air mixture is lean enough, you'll get some random misfires. You've tried fingering the AFM to deliver more fuel, and that improves the engine's running/vacuum. I bet your misfires also disappear when you do that. Right?

http://cgi.ebay.com/ebaymotors/DATSUN-280Z-EGR-TUBE-1977-1978-OEM-NISSAN-/250871773380?pt=Motors_Car_Truck_Parts_Accessories&hash=item3a691f78c4 I bought a fuel pump from these folks. Good outfit! BTW, the easy part is buying the thing. The hard part is getting the old one loose from the manifolds.

Kinky! But seriously, I agree... Contact law enforcement before doing anything else!

I wonder whether it would be possible to modify the fuel level sender assembly to include a fuel pickup tube. It might have to be brazed, but all you would have to remove would be the sender. (You would remove it through the inspection hole in your hatch floor.)

Dave's headlight relay harness is a great convenience, but if you're dirt poor and handy with a soldering iron (like me), then you can DIY with about $10 in parts. Here's how I did mine: http://www.classiczcars.com/forums/showthread.php?35588-Upgrade-from-fusible-links-to-circuit-breakers&p=301787&viewfull=1#post301787 Post #35 The wiring on your 240 headlights might be a bit different, but probably not MUCH different.

Cool! A turbo diesel Z! I have to wonder what the future of gasoline is. We'll always have french fries, and therefore biodiesel. But gasoline? Will I need a Mr. Fusion in the hatch of my Z before I die?

I HAD a gorgeous '75 in Austin, but alas, I no longer own the '75, and I'm no longer in Texas.

What John and Zforce said! Your pressure relief valve is doing its job. I'll only say that 15'ish is a bit low for a warm idle. It might be a sender/gauge incompatibility. It might also be that your oil is too thin. Both my current Z and the Z before it did great with 10W40. When I lived in Texas, I would fill with 10W40 and top off with 20W50. That kept the low RPM pressure up towards the end of each oil change cycle.