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Hello all! I recently acquired a 1977 Datsun 280Z and had a mechanic do a lot of work to restore the mechanics (engine, brakes, etc.) to factory specs. However, there is still an issue. The car starts and runs great, but when it gets warmed up (about 15-20 minutes into a drive) it starts to stutter and then it shuts down. At this point it won't restart. Letting the car sit for about 5 minutes (not a long time!) seems to solve the problem - the car starts again and I can drive it until the process repeats.

Here is what has been done to the car so far:

- Fuel tank checked to see if getting clean fuel from it
- New fuel lines installed
- New fuel pump and filter installed
- New spark plugs
- Distributor checked
- AFM (Air Flow Meter) replaced
- Fuel rail replaced
- Air regulator valve attached (it was missing when I purchased the car!)

The fuel pressure was checked and the mechanic said it was good. So, my question is, what do I check next to see what is causing the car to stutter once it warms up? What other information do you need from me?

On a second note, when the car stuttered and stalled the first time I was driving it (a day out of the shop), I turned on my hazards. This caused my turn signals, hazards, and dash lights to all stop working. To clarify, my turn signals do not work at all. This means that they do not blink outside of the car, nor do the lights turn on inside on the dash. Neither do the hazards. On top of this, none of the lights on the dash come on when the lights are turned on and any electronic gauges (like the voltage meter) do not work any longer. The mechanical gauges (like the speedometer and heat gauge) work fine. The brake light for the emergency brake works. And a red light next to the voltage/charging meter briefly flashes when I start the car.

All external lights work (headlights, tail lights, brake lights), so this is not a dead bulb issue. Since all dash lights stopped working, I am assuming this is not a flasher unit issue. I've also checked fuses and fusible links and they all look good. Where do I go from here?

Thanks in advance for any help. :)

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The hazard switch contacts can get corroded and dirty.  Take it out and clean it up with some contact cleaner.  You might be able to pop it out the top without removing the console, if there's enough wire to get it disconnected.

 

Watch the tachometer when the stuttering problem happens.  If it's working normally, but starts jumping around or reading incorrectly when the problem happens you might have an ignition module problem.  It's not uncommon.  There are other parts that have been known to overheat also, like the fuel pump, and various relays.  Those are a little bit harder to diagnose.

 

Here's a reference.  Read the Engine Fuel and both Electrical chapters.

 

http://www.nicoclub.com/FSM/280z/

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I just may have resloved the engine stalling/stuttering issue. I was looking under the hood and saw that the gas line going into the fuel rail was pressed up against the top of the engine. I thought that perhaps when the engine gets to normal operating temperature that the hose was getting hot via contact and causing the gas to become vapor. So, I moved the hose. It was tied down and I slid it through the tie a bit so that it 'floats' about 2" off the engine.

 

I also saw that the cable going from the distributor to the ignition coil was a tad loose on the ignition coil end. So I made sure that was firmly in place.

 

In any case, I have been driving it for about 45 minutes now, in the neighborhood and in city, so a lot of starting, stopping, and moving slow, and it ran like a champ. Next I will run it on the highway and see how it does.

 

I'll look more into the electrical issues later today.

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The 280Z has been driving well for the past hour, in city and on the highway. Now, a new issue has appeared ... the gas pedal wants to stick. I tried spraying down the linkage with brake cleaner and working it in, but the pedal is still sticking. I have to use my foot to pull it back at times.

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There's a return spring attached to the throttle linkage.  It's kind of hidden behind and underneath the throttle body.  They break.  The boot has little to nothing to do with throttle return besides maybe getting in the way.

 

There was also an issue with the PCV systems up to mid-77 where the throttle body and blade got gummed up inisde with crankcase vapor residue.  There was a Nissan fix, rerouting the hoses, but not all cars got it.  You can fix it, in the medium term, by cleaning the inside of the throttle body with carb cleaner.  Take the boot between the AFM and throttle body off, open the throttle and you might see a bunch of brown varnish and gum inside.

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The AFM had been replaced and I believe the mechanic had looked at the throttle body.

 

When I look at the linkage from the pedal to the throttle body, I see two areas with springs. One is about midway (and I cannot for the life of me see what it does) and one is where it attaches to the throttle body. Both springs look intact.

 

In any case, I disconnected the ball joint where it comes out of the firewall (from the pedal to the engine side of the firewall) where the boot was. If I press this in and release, it comes out part way and then sticks. So the sticking appears to be in this area ... from the petal to this part. The rest of the linkage seems to be working as it should.

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And ... I feel like an idiot. ;) I had checked the carpet and floor mat to ensure it was not interfering, but I did not check well enough. A piece of insulation from the firewall had come loose and gotten wedged. Removing that fixed the problem. :)

 

So, mechanically things seem to be doing alright! Now it's off to find out what's going on electronically. :)

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I went to Advance Auto and had them check the alternator. The man ran the test two times and said the alternator is starting to fail. However, when I compare his results to what is in my Datsun 240Z, 260Z, 280Z, 1970-1978 Automotive Repair Manual, it does not look like it is failing.

 

The print out shows that the charging system voltage on test one is 12.81V. On the second test it is 12.97V. The man at Advance said it should be at 14V or so. However, in the Repair Manual it says the following:

"If it registers over 12.5 volts then the alternator is in good condition, it if registers below 12.5 volts then the alternator is faulty and must be removed and repaired."

 

Since both tests were over 12.5 volts, then according to the manual, the alternator is good.

 

What say you?

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Perhaps I am reading the printed results wrong! The Starter Test reads "Cranking Normal" on both tests. However, the Charging System Test reads, "Results - No Voltage". Despite saying this, it show No Load: 12.81V, Load: 12.81V. If there is "No Voltage" does this mean the car is running off the battery?

 

Sorry for my ignorance on these things.

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Yes, that means the engine is running from battery power alone.  "No Voltage" is being produced by the alternator, either because the alternator doesn't have power to the L wire, or because it's bad.

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Your 1977 car probably has an external regulator, which could be a factor.  Plus, if someone has messed with the gauges, the L wire may not be getting power.  The parts store alternators are of generally poor quality.  People have more problems with new replacements than iwth old Nissan parts.  You'd be much better off to measure a few things on your current setup before replacing anything.

 

And most of the guys at the parts stores that run those machines only know how to connect wires according to whatever instructions they have available.  They don't really know if they're right or not.  Many people have received erroneous test results at the local parts store.

 

Find a multimeter and take a few measurements.

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Thanks. I am an electrical idiot, though I am willing to learn. I'll have to look to see where the external regulator is. I would not get an alternator from a parts store, but had planned to get a refurb, NOS, or one off another 280Z that was known to be in good working order.

 

As far as using a multimeter and taking measurements, I have never done this and would not know what I was looking at. However, as stated, I am willing to learn.

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I just recalled that there's one more possibility, common to the Z's - output at idle tends to be low.  So, depending on what the machine measures, it may have seen no voltage because the the measurement was made at idle speed.  Today's cars have ECU's that bump up the idle RPM to make sure the battery stays fully charged, and the testing machines are designed for them.  Our old Z cars don't have that feature.  One more reason to get a meter and check for yourself.  It's not that hard to do.

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Thanks for letting me know. The alternator that is currently on the car looks almost new ... and the person who checked it at Advance Auto did not ask me to rev the engine, so it was at idle.

 

I'm currently reading through the 1977 280Z factory service manual found here:

 

http://www.xenons30.com/reference.html

 

But I have to admit that the electrical side of things is alien to me. It's just not something I've dealt with yet. Guess it's time I learned. ;)

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Alright! Used a voltmeter and it shows the following when connected to the battery terminals:

 

Car off: 12.8 volts

Car at idle: 12.8 volts

Car under load: 14.8 volts (sometimes getting up to 14.9)

 

"Car under load" is the lights on, fan on high, and engine revving up to between 2000-3000 RPMs. As I release the gas pedal and the RPMs drop, the volt meter's reading drops. So, it looks to me like the alternator is doing it job.

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Alright! Used a voltmeter and it shows the following when connected to the battery terminals:

 

Car off: 12.8 volts

Car at idle: 12.8 volts

Car under load: 14.8 volts (sometimes getting up to 14.9)

 

"Car under load" is the lights on, fan on high, and engine revving up to between 2000-3000 RPMs. As I release the gas pedal and the RPMs drop, the volt meter's reading drops. So, it looks to me like the alternator is doing it job.

 

I agree, your alternator appears to be good.  But some auto parts stores do not know how to correctly test them either.  Before I learned much about auto electrics, I took an alternator in for testing, and it tested good.  But that was only because they did not load it, as soon as a load was presented to the alternator, the voltage collapsed.  It was due to worn brushes, not a bad internal regulator.

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Concerning the car stalling out issue:

The issue to me (and I don't know anything, really) does not seem to be temperature related (i.e. the car running too hot, vapor in the gas line, etc.). Not any more. I've run the car for an half hour, in city and on the highway, and had no issues ... and on a hot day (near 90 degrees outside). Then there are the times that the car is running for only a few minutes and she starts to stutter and stall.

 

If the car is running for a while (30 minutes, etc.) and then stutters and stalls, I only need to let it sit for about 5 minutes or less, and the car starts right back up again (in most cases). The way the car stutters, it is acting more like rust or other junk is clogging the filter from time to time.

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