Zed Head

There is one adjustment - the idle air screw. Maybe that's what you meant by screw? It will affect your CO and hydrocarbon readings. Turning it out leans the idle mixture. I've seen somewhere out there that five turns out from all the way in is a good starting point. It's supposed to set using a gas analyzer. Does it run rich all the time or are you just trying to pass emissions?

Doesn't one or both of the magnetic switches also release to atmosphere so that the vacuum can let go? When you turn the key off, you're de-energizing the switch. Find out why that switch still has power when you're telling it to let go.

Was the "dry" test on a recently run, warmed up engine? That's what you want. You might have been too dry and too cold. If you used the long open tube adapter that comes with some gauges, that will drop the numbers. The adapter adds its volume to the combustion chamber, resulting in lower pressure. I had some 180s drop to about 120, with the adapter (if I recall correctly, I've posted the numbers in the past).

Better to take a spark plug wire off, put a spark plug in, touch the spark plug electrode to ground or ground it with a jumper wire, then watch for spark across the spark plug gap while cranking. With a screwdriver, you have to be more careful with the gap. Too big and no spark, too small and you miss the spark. With a spark plug you can be more sure. Plus it gives you a reason to take a plug out and see if it's fouled. You can also test the coil in a similar way, using the main coil wire. If you get coil spark, but not spark plug spark, look inside the distributor cap. Maybe you just need a tune-up.

Your car has a hydraulically actuated clutch. Check the slave cylinder (down by the starter, on the side of the transmission) and the master cylinder, for leakage. You'll have to peel the rubber boot back on the slave cylinder to look for fluid. Check the reservoir on the master cylinder for fluid.

Could be a shorted water temperature sensor circuit. The lower the resistance the hotter the engine looks to the ECU. Low fuel pressure is a possibility, on the hard starting and the lean intake popping. Have you measured it? The low RPM after it starts could be a stuck closed AAR.

If 5th is correct, then your engine might be running at the proper temperature, you're just not seeing the true engine temperature on your gauge. You might see if the Healey sensor and the Nissan sensor have the same resistance versus temperature characteristics and adapt the wire to the Nissan sensor, or see if you can adapt the Healey sensor to one of the holes in the Nissan thermostat housing.

Could be the ignition module. More details about before, during and after the shutdown would help. Tachometer behavior, is it a dead stop shutdown or are there a few sputters? Automatic or manual? Etc.

I was in the Lynnwood area this morning and saw a 1971 240Z in the PicknPull. It still had the engine in it, with carbs, and there were some odd good parts still left. Rear brake drums, some front end pieces, etc. The bumpers were bent up and there was some other body damage, but there might be something there for a restorer. It is incorrectly labeled as a 1971 280 on their web site - http://www.picknpull.com/check_inventory.aspx?Address=98037&Lat=47.841953&Lng=-122.288181&Make=Datsun&Model=280&Distance=20

The 77 file is the whole FSM, the 76 or 78 is broken in to chapters and will probably download and unzip. They all use the same sensor. Engine Fuel section.

Could be a vacuum leak, letting air bypass the AFM, causing a lean condition. It sounds like the fairly common lean back fire. Higher RPM might overwhelm a small leak, letting the engine run correctly. At low RPM the vacuum leak dominates. Check the big rubber hose after the AFM, the PCV hose, the breather hose to the rocker cover and the various vacuum ports on the intake manifold. Spraying carb cleaner or starting fluid on the intake/head interface and listening for RPM change will find a leaking manifold gasket.

That's a lot more information than in your previous posts. If you had a stuck valve on #4, you should be able to wiggle the rocker arm up and down on the stuck valve a lot more than the others, when the cam lobe is pointing up. The valve lash will be very loose. Or, if you've tried to adjust the valves, the lash might be too tight, holding the valve open. I think that I've also read of the lash pads coming loose and jamming the valve open. Compare how # 4 looks and feels to the one right next to it. With the plugs out, you might be able to spin the engine with your starter jumper and watch what the valves do. Some oil might spray though so have some rags handy. No fuel to the rail and good pressure up to the rail doesn't really make sense. Fuel provides the pressure so you can't have pressure without fuel. This is kind of unintelligible also - "I can voltage with the ignition switch on, but no continuity". Not sure what that means. I would spend more time looking at the valves and rocker arms on #4, and then squirting some oil in to the cylinders and re-running the compression test. If it's rings oil will add some sealing and pressure will rise. If not, it might be a valve or something else. If the intake valve was stuck open, you might get a big backfire, pressuring the crankcase and blowing your dipstick out. That much pressure might have also damaged your AFM, unless the backfire happened while it was disconnected. Maybe you got lucky on that one. Which part of the #4 spark plug was broken? That doesn't sound good either. Taking the head off is a whole new set of problems. Your engine might end up looking like the car in your avatar.

mjr, you've jumped past what your tests showed and maybe spent a little extra money. When you jumped the starter and it worked, you showed that the starter was OK. You probably didn't need to replace it. When the engine fired a few times but didn't keep running unless you used starting fluid, you showed that you have spark but no fuel. For a 75 with fuel injection, there are several reasons why the injectors might not fire. You should focus on that as the reason it won't stay running when the starter is jumpered. When you had the ignition switch apart, you might have tried turning the electrical switch with a screwdriver in the slot (maybe you did this?). This would tell you if it was the electrical switch, the wiring to the starter, or the mechanical part that turns the electrical switch when you twist the key. Basically, break the system down in to what works right and what doesn't. A basic logical approach works best when digging in to these cars, especially with the EFI engines. Even after you get it running, there will be tuning issues that need a similar approach. Good luck.

dont know what pintara is, what is compression ratio of engine with pintara pistons and p90 head? i think that your teck (sic) man said that it would ping with advanced timing not without.

Try the jumper. It will tell you something about whether it's the starter or the ignition wiring. You can also jump directly from the main stud to the blade, using a screw driver.

Is the small gauge yellow wire connected to the male blade connector on the starter solenoid, and making a good connection? You can test starter function also, by running a jumper wire from this blade and touching it to positive on the battery (low budget remote starter). If it cranks, you have a problem with the wiring, if it doesn't, with the starter.

I was off by 1/2 year. Dang. Here's a really good read on Z car differentials - http://forums.hybridz.org/index.php/topic/49194-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount/

I don't think the R200s were used in the Zs until 1975, in the 280Z. You either have an R180 or someone swapped in an R200.

You should adjust the back brakes using the star wheel to as tight as you can without dragging. The excess volume from your loose back brakes probably isn't allowing enough pressure to build up before bottoming the piston in the master cylinder. It's not good for the pistons in the rear cylinders to travel far in their bores either.

Your distributor shaft might be off a tooth or two. Apparently it's not uncommon. Or your plug wires could be off one spot at the distributor cap. If you find that the pulley mark is at TDC, you can either moved your plug wires over one spot or see if the distributor shaft can be moved. Two options.

Since you've had it apart, you've seen the thin narrow rod that turns the switch. You can take two pliers, and twist/bend that rod in the direction that the key turns, to get it to move the electrical switch farther when you turn the key. My car had a similar problem where sometimes it wouldn't start (maybe the same, your description isn't very clear), probably just from mechanical wear. Bending the rod fixed it.

If you have a voltmeter you can work from "first principles". The coil positive terminal needs power when the key is On and at Start. Turn the key to On and find the wire with power, connect it to the positive terminal. Do the same with the key at Start. I would do this anyway just to verify the wire colors are correct (for example, one person's green might be another person's blue).

If you've owned the car since it was new then the only way you should have an external regulator is if you or one of the mechanics who had worked on your car had installed one, unless there was some odd factory leftovers. Nissan went to the internal regulator in 1978. I'm no expert on the history of these cars but that would be a very odd thing to have on a 1979 car. Do you have picture? I converted to an internal regulator on a 1976 car, but in retrospect there was no real advantage gained besides availability of parts, and maybe reliability, except for the fact that the rebuilt alternators available today usually fail at the internal regulator. An external regulator might actually be more reliable unless you use Nissan-made internal alternators.

It could be fuel pressure. Steady fuel pressure at the factory spec. is necessary for the ECU to do its job right. Even if the pressure looks good at idle or tested with the engine not running, sometimes the fuel pumps will lose pressure at higher flow or when they get warm. Knowing fuel pressure is one of those things you have to do. I recently picked up a brand new pump (shiny) from the wrecking yard and it only lasted about 20 minutes while I was testing it at home. It had had some water in the fuel lines (gallons according to (the yard guy said 4 gallons came out of the tank) and must have rusted the guts of the pump (luckily they threw it in with the spare engine I was buying, so no real loss). It may seem like a waste to buy a pressure gauge for $40 only to use it once or twice, but you can save a lot of money in the long run. Many people recommend hooking up the gauge, running the hose out of the hood where you can see it, and taking the car for a drive while you watch it under load at higher flow. Pressure should not go much outside 30 - 38 psi while you're driving. p.s. Just re-read my other post and it seems harsh. Sorry about that. Good luck with the car.

A walk though the wrecking yard might be worthwhile if there are any Zs or ZXs there. I found a set that looked either factory new or newly rebuilt. Nissan brand. Often, people will replace many parts before giving up and junking a car. You can tell at a glance if the injectors are new, old ones are typically rusty and corroded.