Need diagnosis asap!!!

[mike's78z]

I bought a 78 280z last week and the owner claimed that the fuel injectors were leaking. So I replaced the injectors and fired up the engine. I noticed a change in power but the engine was still sputtering. Every so often it made a loud popping noise and spit out black stuff from the exhaust. So i thought perhaps it wasn't burning the fuel. I also examined all the spark plugs and found that they were all jet black with soot all over them.

After that, the car wouldn't start again. So I gave up and started changing out the headlights.To my surprise the old ones didn't have a bulb. When i tried to turn on the headlights nothing happened.

My question is this, based on all of the facts i've presented what could be the cause of the problem? Is it an electrical issue? Do I need to replace the spark plugs? I needed to have this car running by the time i moved this Sunday. So Thanks to anyone who can be helpful.

[hls30.com]

1) the car is running horribly rich.

2) clean the plugs and reinstall if they are NGKs if they are any other brand get NGK BPR6ES-II

Check the AIr filter-see if it is clogged up-with the backfiring, it could be too restrictive to pass enough air into the engine-get a new one if needed-start the car and see if performance improves.

3) with the engine cold, unplug the cold start injector and try to start the car. If it runs right, then

a) look for new tape in the harness going to the temperature sensor-sometimes people will put a resistor in line with the sensor to add fuel thinking this will give better performance with no other changes-unless the car is running lean it won't-if you find a resistor-remove it from the circuit and reconnect the wires.

b)look at the Airflow meter, see if the plastic access panel looks like it has been removed-sometimes people will bend the sweeper to add fuel.

4) check your fuel pressure regulator to see if it is working-and check your fuel pressure.

WIll

[ChrisZ]

And also check your ignition timing, it can be to much retarded.

Chris

[mike's78z]

How do I test the fuel pressure and where is the cold start injector you spoke of?The air filter looks clean but its all warped. It kinda looks as though it got wet, then it went out of shape and dried that way. Also I checked the oil and its black as well. I'm thinking its had this problem for a while. Lastly I noticed the floor temp. light came on when the dashboard lights were working. Could this have any connection?

I forgot to mention that for some reason the dashboard lights aren't turning on now. I noticed this the first time when I changed out the injectors and it wouldn't start then either. I thought it just needed to rebuild fuel pressure. Somehow the lights came on again and the car started. However when I took out the spark plugs to clean them, it turned off again. I know I unplugged the neg. cable from the battery both times, but its connected now. The starter cranks but that's it. I really wanted to have it running well in time for my ceremony.

[sblake01]

Two things: The fuel pressure test and the location of the cold start velve are outlined in the FSM in the EF section. The other problem sounds like either a bad ignition relay or a bad connection at the ignition relay. You say the car started when the dash lights came on. The EFI system and the dash lights would both be fed initially by that realay.

[FastWoman]

Some great advice above! I think HLS30 and Sblake are both spot-on. Just to add a few more perspectives:

Too rich a fuel/air mixture is going to cause the popping, the sooty plugs, etc., but it is not likely to cause the engine to stop running altogether. That sounds much more electrical (e.g. the the ignition relay). The key piece of info here, as sblake pointed out, is the correlation between the dead instrument panel and the dead engine.

The relay itself is only one potential problem. It could also be a fusible link or a bad connection (or other things too). You really do need a factory service manual to work through these sorts of problems. You can download them for free, and others here can probably tell you where. You can also buy a paper copy (highly recommended!) off of Ebay or Amazon. They cost about $80 in great condition or about $30 in the condition I bought mine.

Meanwhile, in hope that it might get you to your ceremony in time:

(1) Find your fusible links. They will be 4 wire loops (2-3" long) beneath two white, crumbly/missing covers, attached to a black metal box on the righthand side of the engine compartment. Give them gentle tugs. Have any of them come apart? (If you know how to use a multimeter, is there should be +12V on both sides of the wires.) If any of them are bad, don't just replace them with ANY wire. You need new fusible links.

(2) The engine relays are in the black box the fusible link assemblies are attached to. Remove the plastic cover on the rear side (by removing 3 screws). Look inside. There are your engine compartment relays. Are any of the connectors unplugged? Are the connections dirty? Try cleaning and lubing with WD-40, and work the connections.

(3) Look inside the firewall, just above where the passenger's feet would be. You'll see a couple of huge nylon connectors between fat sections of wiring harness. You'll probably have to remove a black plastic trim piece, just above the carpet, to see them. That's a major point where your wiring harnesses link together. Unplug them, and inspect. If they're really hard to unplug, try working them apart with a flat-blade screwdriver. Inspect for any connections that look burnt (i.e. with melted plastic around them). Again, clean/lube with WD-40, and work the connections to clean them. Similarly inspect/clean any other connections you see.

(4) Look up and on the righthand side, well above the fuse block. You'll see more relays. In the middle of these is the ignition relay. Check all the connections there.

Hopefully this gets you running. However, if it doesn't, you'll need to trace further:

(5) I *think* only 3 relays are critical for your engine running -- the ignition relay (see 4), the fuel pump relay, which is in the top middle position in the engine compartment relay housing, and the fuel injection main relay (the right-most upper relay in the engine compartment housing). It's possible might be plugged in a bit differently, so check all the relays in the engine compartment housing that have 4 conductor connectors. The one you want will have a blue wire with a green stripe. Have a friend turn the key to "on" while you feel each of these relays. All of these essential relays should "click."

(6) Is your fuel pump running? Unplug the little wire from the starter solenoid, and turn the key to "start." Listen carefully for the sound of your fuel pump running back by your gas tank. Mine makes a muffled, low-pitched vibration. My old '75 made a quiet, higher-pitched whine. Plug the starter solenoid wire back in after you're satisfied the fuel pump is running.

If none of these get you running, then this is too big a job to tackle in a day. Close your car back up, and go order a factory service manual. Plan to spend some time picking through your system to find the problem. Even if your car starts up, order the manual for next time. BTW, if your car DOES start up, you might check the status of your AAA membership. You could well need a tow, here and there, until you get your car on a more solid footing.

BTW, just a quibbly point about plugs for your '78 (which you should probably replace): The factory spec plugs are NGK B6ES-11. The "P" would be for a projected plug, which I think was a 240/260 thing. With fuel injection, the proper plug is non-projected. The "R" is optional. It's the resistive version of the plug, used for noise suppression. If in doubt, you're probably better off with the B6ES-11, at least until you get the car running. (This is a very minor, quibbly point, though.)

[zpizzaman20]

You guys are good!

[mike's78z]

Sadly, I didn't get to take the 280Z to the wedding, but at least I got it stored. Before I stored it, I made some more inspections.

1. I found that there may have been a faulty wire where the fusable links are located. They didn't have any covers, but it was at the location described. I jiggled the wire and I heard the warning sound that goes off whenever the key is in the ignition. The lights on the dashboard turned on as well.

2. I then tried to start the car, but was not successful. The starter cranked but there wasn't any signs of it starting. Then on the third try it sounded like the battery was dying, but the gauge said I still had half a charge. I don't know perhaps the voltage gauge was wrong?

When ever i get the chance i'll check it out again. However, since I moved so far away I don' know when i'll get to check it again. Thanks for info guys, it really helps.

[FastWoman]

Hi Mike,

Sorry you didn't make it to the wedding. It could well be that you have multiple fusible link problems. The best way to know they're all conducting is to get a multimeter (or volt meter) from Radio Shack or the hardware store. They're incredibly cheap these days -- maybe even $5. (I once found a bunch of them on sale for $5 and stationed them in the emergency kits for all our cars and boats.) Anyway, touch the negative probe to the negative post on the battery, and touch the positive probe to each connector on each fusible link (i.e. 8 readings total). Poke at the connector pretty hard, so as to make good electrical contact. All the terminals should read the same as the voltage at the + terminal on the battery (ideally 12.5V or higher). If you find a fusible link that reads +12 on one side and zero on the other, the link is bad.

Regarding your half-charged state... Did the volt meter read 12.25V (the half-charged voltage for a lead-acid battery), or was it 8V (half of the 16V full scale)? If it was 8V, your battery was quite dead and wouldn't have turned your engine. Even 10V usually doesn't turn an engine. If the voltage falls below 12V, you're better off not trying to crank the engine, as you can really destroy your battery.

Anyway, good luck with your Z, whenever you get a chance to work on it again. Don't let it sit too long, or your problems will multiply in a hurry.

[mike's78z]

Come to think of it, the battery was probably low. I just glanced at the gauge and thought it was still ok. I think it goes up to 16v, so it was probably around 10 or 9 when i tried to start it. I wonder why it keeps draining the battery? When I test drove the car they had to recharge the battery and when I bought it they put a new one in for me.

Now that I've had the chance to look over the car, I've noticed a few things here and there that I'm not too happy about. For instance, the paint looks surprisingly good for it being over 30 yrs old. I found overspray on some electrical components which indicates its not the original paint. Same goes for the interior. The $3,000 that the owner said he put into it was probably just to make it good enough to sell.

Question: How many years does it take in order for an old car to be smog exempt in the state of California?

My stepfather's 75 chevy pickup is exempt, but my uncle's 77 dodge pickup isn't. They told me it was something around 25yrs or so. Right now I have my car registered as non op, but if I were to register it would I have to smog it? I heard there were people who swapped out motors, but were still able to register. If this is possible, I might just be the solution to my problems.

[mike's78z]

The last year for smog exemption in CA is 1976. Darn California legislators...

Edited September 29, 2009 by mike's78z
corrections

[sblake01]

The last year for smog exemption in CA is 1976. Darn California legislators...

A 76 and newer has to be smogged in California. 75 and earlier are exempt. Edited September 29, 2009 by sblake01