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Discussion Starter · #1 ·
I just recently aquired a '77 280 Z 5-speed, with @130,000miles which I bought mostly as an every day driver (I love it--and I expected some problems--I'm optimistic not foolish), however it has developed an interesting problem that I am not quite able to diagnose--my car periodically goes on strike. That is, it will just shut down . .no hesitation. . .no regularity. . .it just stops running at any speed!! Starting the car back up is no problem. . .first turn. Sometimes it does develop a nasty backfire in the exhaust (One big one followed
sometimes by one or two small ones. I did a tune up on it and it helped for a day or two, but the problem crept back up on me. Somethings that I have noticed about the car:

When the car shuts it just stops as if I turned the key to the "off" position

If I rev the engine in neutral and bring the RPM's to 3,500 RPM the car will falter--meaning that the RPM will drop to 3,000 RPM then back to 3,500 then back down etc. This happens sometimes, but it does coincide with the above problem.

The behavior seems more often to develop after a lot of stop and go driving although the car has effectively demonstrated that it will quit whenever it wants not always following this pattern

The car always starts within the first three tries in the morning, although it does need to warm up slightly before driving in the morning and idles correctly at 800 RPM

Sometimes when I drive it and stop at light, I notice the RPM sometimes increases to about 1,000 with the car in neautral, a slight tap on theaccelerator brings it back to 800 RPM

The timing seems ok (10 degrees BTDC)

When I remove the oil filler cap when the car is running it will begin
to stall

The plugs are fouled in a way that tells me the car is running rich (black sooty plugs--but not the worst I have seen)

When I replaced the rotor it seemed unusually burned on the one side of the metal tip

When I replaced the distributor the metal elements inside had a light gray coating along the path of contact with the rotor--this coating was not flaky or crusty but could be removed as a whole

The valves do sound like they need to adjusted for clearance

The the gear shift lever gets noticeably hot to the touch

I am hoping that maybe you can give me some insight so as to cut down my troubleshooting time. Going through the whole entire fuel, ignition,and emission systems is a lot of work that I would I gladly do if I absolutely have to. But I still prefer to to cut that time in half (especially since my wife seems a little jealous of the car).

Thanks, Joe
 

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Discussion Starter · #2 ·
hey joe can't fix all of your problems but a suggestion that works for me soemtimes is to run techron (a fuel and engine cleaner) through your Z don't get the cheap crap either. Also make sure all vacum lines are in good shape cause if i'm not mistaken vacum runs that fuel pressure regulator(on the injector rack)basically clean and scrub adn the problem will present it self.
 

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Good advice Joe

Especially the vacuum lines - this is the bane of older Z cars and causes all sorts of wierd problems. It is normal for the motor to stall when removing the oil fill cap.
 

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Can't give you an answer to all of your issues but here is a suggestion on a few.

a) gear shift- your inner boot may need to be replaced.

b) oil filler cap- Z's run a pressurized oil system and that is what will happen when you open it up.

c) quiting- possible voltage regulator issue as mine did the same thing. $25 to $30 to replace located on the passenger fender wall in front of the battery.

d) running- would do a tune up consisting of plugs, wires, distributor cap, coil, vacuum advance, vacuum hoses, fuel filter, fuel pressure regulator, pick up reluctor and replace all vacuum lines.

Hope this helps. Keep us advised. :>)
 

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Discussion Starter · #5 ·
<b>Couple of Thoughts</b>

Although I can't tell you precisely what to look for, here are some thoughts I had from your description of the problem...

The fact that it dies the way you describe at any speed indicates to me that something in either the fuel or ignition system is shutting down intermittently. Next questions are: which components could cause that and how do you find an intermittent problem? If you have a manual for the car, I would go through both the ignition system and fuel system and make a list of which modules are susceptable to intermittent failures and look at ways you can test them quickly the next time it happens. Cap and rotor would not be on this list. I don't right off see how vacuum problems would be on this list, unless there is a way vacuum can completely shut down your fuel or ignition system that I'm not considering.

In the ignition system, perhaps the coil, electronic ignition module and certain power/ground leads would be on the list.

In the fuel system, perhaps the electronic controller (under the dash) and certain wiring would be on the list.

Again, it is best to go through the manual and come up with ideas. Some units might be worth just replacing with a known good unit (Z Barn in TN sells some of these units fairly cheap). Others may be able to be monitored somehow.

Intermittent problems are the worst... Good luck!
 

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Discussion Starter · #6 ·
RE: Couple of Thoughts

Fuel pump relay could be nominal. Coil could be nominal. Voltage regulator could be nominal. Also, it is possible that it is a relay under the hood.

These intermittent ones are the WORST! but Tom D. is on the right track with this one.

My strongest feeling is toward electrical, because I had a fuel pump die on me recently and then the car dies with jerks and sputters, just like running out of gas.

Instant off as you mention is either fuel-injector-electronics related (dropping resistors or ECU) or spark related (all the way from ignition switch up to the coil).
 

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Discussion Starter · #7 ·
RE: Couple of Thoughts

Possibly a loose ignition wire, if the wire that keeps it running pops off, thats it, dead.

-Adam Boyd
 

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Check your fusible links

I had a similar problem with my old 78Z intermittently shutting down when I first bought the car. The two fusible link connections (2 black and 2 red) in the engine compartment on the passenger side of the motor will sometimes get corroded and an intermittant connection will develop. This will shut down all electrical power to the engine immediately.
However, usually a slight wiggle of even a breeze will restore contact at the links and the car would restart just fine. Almost ALL 280Zs that I have seen are either missing or have broken fusible link covers. I would clean the copper contacts and make sure the actual "links" are in good shape or just replace them, and buy two new plastic covers if your Z is missing them. I think it's about a $35 fix.
 

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Discussion Starter · #9 ·
RE: Check your fusible links

I will go along with William
But clean ALL electrical connections under the hood
can't hurt.
Dave S
 

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RE: Check your fusible links

Joe,

I have had this same problem several times over the 14 years I have owned my '77 280Z. As William said, check the fusable links. This is almost always the cause of this problem. I keep a light coat of axle grease on mine to keep the corrosion away.

I have had two three other causes, all electrical:

1. Ignition relay is held to the bracket by one screw. If it vibrates loose and the relay isn't making good contact to ground, the engine will suddenly die as though the ignition switch is turned off. This relay is under the dash on the passenger side...up and to the right above the fuse panel. Make sure all screws are tight and electrical connections are corrosion free.

2. Corrosion on the fuse holders (clips). Periodicaly remove the fuses and clean the clips with a Q-tip and solvent. Then, with another Q-tip apply a very light coat of gun grease and wipe off any excess. Replace the fuses.

3. Corrosion on the plugs of the harness going from the interior to the engine compartment. You will have to pull them apart and squirt them with Radio Shack terminal cleaner. When I first did this, I was surprised at how much brighter my headlights and dash lights were. In that particular case, the wiring from the ignition (key) to the engine compartment had a corroded plug.

Hope this helps.

Don

I hope this xtHoucable
 

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Discussion Starter · #11 ·
<b>check this too...</b>

My 73z shut down erratically for some time before I accidently figured out it was the switch behind the ignition key. I reached to scratch my knee, and bumped the keys and BANG!! The car would backfire like a canon going off and shut down. This was easy and really cheap to replace. Check to see if your key feels a little loose or wobly when you drive the car. The other guys above have good ideas too, try the cheap stuff 1st. Good luck.
 

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Discussion Starter · #12 ·
<b>READ THIS!!!!!!!</b>

Thermotime switch. On the front of the thermostat housing. Been there done that. Wires get frayed and beat to death from water/dirt/crap. retainer clip still on? If this thing even moves a little bit while the engine is running your machine will shutdown pronto. Also if the switch is going bad(yes its a THERMO switch and can go bad due to heat/cold/heat/cold alot of use)then your machine will run like **** when its cold and good when warmed up OR great when its cold and shitty when it warms up, depends on where the switch is stuck...get it?

Drop resistors dont go bad/good/bad.
ECU is an analog system with no memory. Usualy If its bad its bad. If its good its good. Cableing is another monster altogether.

Fuel regulator? Have Run this off before. No biggie.

Fuel pump switch? Under dash, silver canister, hard as **** to get to. Two relays inside..operates on the ignition switch. Probably not the problem, cause switches go bad. Not bad/good/bad. Ignition switch...maybe(doubtful).

As incorrectly posted before...the motor does not run a pressurized air/oil system...what the ****?
When you take the filler cap off it dies because the positive crankcase ventilation system goes ape ****. (Its supposed to do that..no biggie)

enough of me.

Good luck
 

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RE: READ THIS!!!!!!!

I'm going to have to go with the destroyer on this. The intermittent nature of the problem and the fact that it most often occurs on around town stop get out, get in and go driving points to an electrical problem which is exacerbated by engine room heat. If you have tentative wire connections in the engine compartment (got a Z? then you do.) and you heat them up they expand and get sloppier. They will get especially hot when you go to the "Stop and Rob" for a Slurpy and the fan is off and coolant no longer circulating for a few minutes. At this time the TT switch on the front of the motor "by accident" is telling the ECU that it is morning-cold start time. Automatic way-rich and backfire like crazy if you can even get it to run at all. Then as it sits and sputters with the fan blowing on it cooling the connector and contracting it suddenly it starts to run better.
All that is happening when you remove the oil filler or for that matter the dipstick is a sudden massive vacuum leak. In fact if it doesn't kill you are probably dealing with a well compensated constant vacuum leak. Good luck...
 
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