Zed Head

Here's one. Spendy. http://www.thezstore.com/page/TZS/PROD/11-2972 Are you that you actually need one? There are more 300ZX people on zcar.com.

I don't know if this will work but it seems like it might, if my limited understanding of how the tach works is close. It uses the GM HEI module as the "pulse" source for the tachometer. One scheme is for the 240Z current-reading tach, and the other is for the voltage-reading 280Z unit. Serendipitously, the factory GM HEI module limits current to about 4 -5 amps, apparently. The current through the 240Z tachometer should be about 4 amps, so it's a pretty close match. 13 / (1.6 + 1.6). Primary circuit coil resistance and ballast resistor are both 1.6 ohms. 13 volts is nominal battery voltage. The 240Z tach just sees voltage rising and falling as the coil charges and discharges. The HEI module charges and discharges the 240Z tach, in essence. The current limiting of the HEI module should protect it from too much current, although I'm not sure if it responds fast enough. Might need a resistor in front to help out. The primary resistance of an HEI coil is about 0.5 ohms. The 280Z just sees voltage rising and falling and has a big resistor in front of it. So all that should be needed there is the connection to the C terminal to see the voltage change. Here are the schematics. I'm no electrical engineer and could be way off. I saw the wiring schemes for the MDS 8920 adapter though and this thought came to me. Please pick away at it, if you know something or have a suggestion. Or just blow it up with massive electronics knowledge. I can take it. My main concern is that the HEI module will burn itself up with no load on the C circuit, but the current-limiting should cover that, I'd think. Or the 240Z tachometer will fry, but again, 5 amps should be handleable. Any experiments could be done with a 5 amp fuse in-line to save parts. One other benefit is the automatic shutdown of the HEI module if there's no activity on the C circuit within a certain time. Just trying to keep the old brain sharpened. 240Z G - ground W - white trigger wire Mount grommet - ground C - ground B - tachometer - battery power HEI module passes ~4 amps, current-limited. 240Z stock has 1.6 ohm primary + 1.6 ohm ballast resistor, 3.2 total. 13 volts (nominal) / 3.2 = 4 amps 280Z G - ground W - white trigger wire Mount grommet - ground C - factory resistor - tachometer B - battery 280Z tach only sees voltage pulses, essentially no current. The module just lets the voltage pulse from ~0 to 13 as the trigger switches the module. It's a "phantom" coil.

My point was that without enough air flowing through the AFM to open the vane the contact will stay open. No vane movement, no fuel pump power. The contact can be perfect, just not closing to actuate the fuel pump relay. Maybe you meant that the vane can be seen moving at idle? If it will stay running at higher RPM, even though it's missing, you could open the idle speed screw to let it run by itself.while you watch the pressure gauge and fiddle with hoses and wires. Or put a brick on the throttle pedal. It shouldn't take 3000 RPM though to open the AFM vane. And the reason I suggest these things is because you can't have zero fuel pressure AND 3000 RPM. So there's a disconnect there. There must be fuel pressure, either too high or too low, One way that you can have low pressure but rich air/fuel ratio is if the FPR diaphragm has a hole in it. The vacuum hose to the FPR will pull fuel straight through the FPR in to the manifold. It's not uncommon. Just suggestions.

Overall, it looks like you have the typical collection of problems and adjustments to the wrong parts to fix them. It still looks like the fuel pump contact in the AFM is closing because of low air flow, or the AFM is still out of adjustment, causing the vane to stay closed. You need to set the AFM back to where it was so that the vane can open and keep the pump running. Or stick that wire back in there. You can check the function of the fuel system by disconnecting the small wire from the starter solenoid and turning the key to Start. The AFM contact is bypassed at Start and the pump will get power. I think what's happening now is the pump is getting power, then the engine starts and you're letting go of the key. The AFM vane is closed so the power goes away because the Start bypass is gone. When you rev it, the vane opens for a second, the pump gets a second of power, etc. You're about at the point where hot-wiring the pump just to be sure the power stays on, would be the thing to do. I think you might be working on the wrong thing. Get the pump powered permanently, either via hot-wire, or hard-wire in the AFM throat, and start the engine, See what pressure does then. Forgot to say - the old FPR's tend to leak down quickly. So if you try the solenoid wire disconnection test, you'll need to be able to see the gauge while you hold the key to Start. It won't hurt anything, the pump stays on for hours while you're driving.

Many of us use our cars as "reasons" to buy new tools/toys but really, cutting wires, stripping the ends, and reconnecting with naked butt connectors and shrink tubing would be a perfectly viable way to get it done, as far as functionality. Makes some people queasy but the method has survived the test of time. Once it's done and the AFM is plugged back in, you might never remove it again.

Maybe he already has the head off and is measuring for warpage, and looking for cracks. Could be. 51 degrees in Nampa, good car work weather.

Your news came out of nowhere. I hope it was just a random event. Good luck.

You've gone 1/2 circle, from not enough pictures to not enough words. If you're trying to indicate that there's definitely water in the oil, then...bummer. Check the cylinders for head-related problems. Spin the engine with no spark plugs. If any water droplets at all show up, you'll need to pull the head. If the PO replaced a head gasket because of overheating he should have had the head checked for warpage. You might have bought a problem engine.

People usually do this when they remove an engine or do a big repair. Did the PO say what he had just fixed before you bought it? Looks like you'll have some checking to do, even if you get it running again. Just to be sure. It's all part of the fun.

You have a 1976 car. Site was right. That's probably the stock engine. Compare the title VIN to the VIN I underlined below. While you're waiting for the oil to settle down in the clear container (the water will separate to the bottom) get a meter and run the tests shown in the Fuel Injection Guide. Make sure that the coolant temperature sensor reading is correct.

If you really want to know, you'll pour the oil in to a clear container. Water will separate out eventually if it's in there.

That oil doesn't look milky. It seems clear, I can see the concrete underneath. You might be on a wild goose chase (this would be good). Looking at your engine picture, the blue stuff looks like tape. Are those wire ends that are taped together? Could be that your coolant temperature sensor wire came loose. There's hope, don't do anything crazy. What is the date I underlined in the picture. Can't see it.

To SteveJ's point about not trying to start the engine. It might be worthwhile to remove the spark plugs and spin the engine with the starter. See if coolant comes out of any of the spark plug holes. People do see that sometimes if there's a leak in to a cylinder. If there's enough coolant to hydrolock, it will spray from a plug hole.

The fuel rail is 75-77 style also. Three piece. Could be a replacement motor. Not a huge deal, but something to be aware of. Good pictures of the oil and the spark plugs will tell something.

Not really clear what you're saying. "When we had the car"? When? How long did it run perfectly before you parked it in the garage? Since it's your first car,and first Z, the best thing that you can do is to read through the Service Manual. Engine Fuel chapter. See the link below. Your fuel pressure is too high, for starters, but there's much more in there. On the pictures, I really wanted to see the " chocolatey color, which means water." Dark chocolate would be okay, milk chocolate would be iffy. White chocolate would be bad. Could be that you've assumed the wrong problem though, there are several things that you can do to confirm. Since you put new spark plugs in, the old ones should be available for pictures. Where's the tub full of oil that you drained? If you give more information, you'll get some good ideas from out here. http://www.classiczcars.com/files/category/4-manuals/

I wasn't really asking about Skype. We need pictures, however you can get them. I don't think anyone is here to do an online realtime diagnosis. How long did the car sit, and how did it run when it was parked? Maybe the Datsun mechanic was right and you let a leaky roof drip water in to the engine. I asked if it was cold because frozen coolant can crack a head or block. Maybe even lift a head, causing a gasket leak. Are you using antifreeze in the coolant or just straight water? Need to figure out water got in to your oil. If the car has sat for a year or two it could be condensation. You're a bit limited because you know not much about cars. "New head cylinder" in your first post is a sign, and is most likely why the parts guy sold you some "head crack sealer". He'll probably keep selling you stuff you don't need if you go back. Be careful.

Don't take advice from parts store guys. Most of what the typical parts guy knows is what they heard from other people like you. Your retired Datsun "mechanic" gave strange advice. Or you misunderstood what he said. His suggestion of water "going in to the engine" and letting it sit for 24 hours then refilling with oil is odd. If you can run Skype, maybe you can use your computer to grab a picture. Or just take picture with whatever device you're using Skype from. In short, get a picture of the oil on the dipstick. Check the plugs as suggested. Has it been cold in Nampa? In your garage?

Here's a picture of the Schrader valve on a 1997 Honda Passport. The same year Isuzu rodeo has one also. Has a black cap, right in the middle of the red square. Easy to remove. You'll find many other valves on many fuel rails but they'll be difficult to apply to the Z.

Stanley - sorry to fill your thread with tach arguments. There are enough brainy electrical guys on this forum that you'll probably be able to get your tach to work. CO and SteveJ are out there. Might take a few tricks though. The guy in Chickman's Hybirdz thread actually used the MSD 8920 adapter instructions correctly to get his tach to work, he just ran the current backwards through the tach. People have amped up the current effect even more by taking their 240Z tach out and adding more wire loops. Actually the brainy guys could probably figure out what that 8920 adapter is doing. It's wired kind of like an ignition module.

Are you actually running that Haltech? Your last few posts said that you will be running a Haltech. Thought you were still collecting parts. As far as skill level - it's just connecting three wires, for the 8920 adapter. A corollary to what I said above - the guys who connect three wires and end up with something that works feel like electronics experts. The guys who connect three wires and get nothing are left hanging. It's just three wires.

Actually, within that thread is the typical scene. Works for one guy then the exact same setup doesn't work for another. 72_NorCal didn't get it to work, Post #4 and on. The people it worked for say it should work for everybody. And the people it doesn't work for are left hanging.

Looks great in words. But I'm sure that I could find a case of "it didn't work for me" for every one of your examples. There are lots of posts all over the internet about people who can't get their tachs to work. The latest I saw is a Megasquirt application. madkaw was there and you too. madkaw's pretty good with easy-peasy stuff. http://forums.hybridz.org/topic/124640-240z-tach-driver/?hl=tachometer#entry1165438

I've seen that before and it seemed like a lot of mixed results. Edited a bunch of my comments out. If you read through that thread you'll see people who had no problem and people who've tried everything and still have problems. I don't see one method that's guaranteed.

1973 is different from the 280Z's, and the 260Z. Probably had somehting to do with the introduction of electronic ignition. Power runs through the tachometer first, then to the coil. In the 280Z's and the 260Z power runs through the coil first then to the tach. So by inserting the Hi-6 box in between the coil and the tach you're affecting the trigger for the tachometer. Feel free to walk him through it though. Tach problems are common with the aftermarket boxes.

I think that you're going to have tach problems. The instructions show that the power wire to the coil positive, that runs through your 240Z tachomoeter, is cut and redirected to the Hi-6 box. The power characteristics in to the Hi-6 might be different than the power draw from the coil positive. The stock configuration pulls a bunch of current through the tach loop, then stops. The Hi-6 probably has a more steady draw, or spikier. But not the same. Your tach would be where the red arrow points. Before the coil. Now it's before the Hi-6 box. Edit - took out a bunch of CDI stuff. I don't really know why one is better than another or if one is.