'79 280zx problems... again

[DoctorRobert]

Ok, I made another post a month or so ago about problems I was having the car - and I got it running again. And it's been running fine, until today.

With no signs of problems or anything on my way to work today my car just shut off while I was going down the street. No sputtering or choking, just off like I had turned the key off.

I rolled the car backwards off the road and into a parking place and after at least ten times of it turning over, without even trying to start, it started up like there was nothing wrong. I drove it to work, and parked it. After work I started it - it started fine, I revved it a few times, it did fine and then - off, just like I turned the switch. After that I sprayed starting fluid in it - nothing. I replaced the plugs - nothing. Later on I pulled a plug wire and attached it to one of the old plugs and set it on the engine to see if it would get fire. I did see an arc but every now and then from the plug, so while my friend tried to start the plug I got it close to metal and it sent a spark from the plug to the metal and at the same time the car fired up. I ran it for a long time afterwards, but I don't trust it. I drove it around in the yard and revved the motor. Stopped it and started it a bunch, but it starts again like there's no problem. But I don't trust the car, and have no idea what's been going on, so... any help?

[evildky]

intermitant failures can eb tough to diagnose, when the car died and woudl not restart, it woudl still crank, right? might be the ignition module, there is a black box ont he side of your distributor, it might be going ut, could also be a bad fuel pump, ecu, fusible link or a number of other parts, but the ignitor would be my first suspect

[DoctorRobert]

Yeah, it wouldn't start, but it would turn over - like it wasn't getting any fire.

One thing that I forgot to mention is that after about fifteen minutes of not trying to start it I would crank it and it would fire up for just a second, but then shut right back off. That led me to believe it might be a fuel delivery problem, but then it wouldn't start even after I sprayed the starter fluid in it.

I can say one thing, and I have NO idea if this has anything to do with the car starting or not, but I wiggled the wire on the side of the distributor, and it was after that the car actually started. But that would have been coincidence, since it started randomly earlier.

What should I replace first...?

[evildky]

I'd suspect the ignitor

but to deterine what to replace you need to determine what the problem is, when ti won't fore you you need to determine if you ahve fuel pressure, if the injectors are opening and of the spark plugs are getting spark, that little black box will prevent eh injectors form firing and the plugs from firing

[DoctorRobert]

Okay, I know how to test if the plugs have spark, but how do I test if the injector's are opening?

My girlfriend actually drove the car today, and it ran fine this morning, but this afternoon she says it started choking off and then just died on her and wouldn't start again. Now, I didn't choke off on me when it died, it just shut off like a switch was turned, so I don't know if - to put it bluntly - it was actually choking or not.

[DoctorRobert]

Okay, I just pulled a plug and they are definitely getting fire. However, the new plugs I put in there yesterday are now black....

I sprayed starting fluid down the intake and it ran for a few seconds, so with the aide of the girlfriend I sprayed starting fluid into it while it was running and it continued to run, until I stopped the fluid.

However, I also found a thin coating of oil in the tailpipe and it is lightly blowing gray smoke.

Any ideas?

[2Fast280ZX]

Check your timing, I believe it could quite possibly have something to do with that.

Try clocking your distributor a degree or 2, it may have shifted slightly if the bolt wasn't tightened properly.

did you replace the Distributor or Rotor recently?

[DoctorRobert]

Yes I replaced the rotor about a month ago.

[2Fast280ZX]

Yeah, then check your timing, that could definetly have something to do with it, In fact, that same thing happened to a friend of mines 300ZX a couple weeks ago, he replaced the rotor but didn't get everything tightened back properly and then a couple weeks later it started to twist his distributor and mess everything up. Well I hope it works.

[evildky]

the fact that it sterted with starting fluid but not withut tells us you have a fuel problem, forst verify fuel pressure, this is easy, just pull the fuel line and put it in a bucket and try starting the car, it should be pumping gas, if not, you have a bad pump

[DoctorRobert]

Today the car is starting again, and (obviously since it's starting) it's pumping gas. Would it be doing this off and on again if it was a failing fuel pump? I guess I'll just have to wait until the next time it acts up to check the fuel pump. I'm not driving it daily now, since it's got it's problem, but it seems as if when it sits it'll run for a little bit before crapping out again.

Next week when I get paid I guess I'll just replace the fuel pump either way... unless I find out it's for sure something else.

[DoctorRobert]

If it's a faulty fuel pump would that still cause it to run intermittently?

Because every day I go to crank it up it starts and runs (idles and revs) just fine. I haven't driven it though, because I don't trust it (obviously).

The only thing I notice funny about it, is when I rev it after I release the gas pedal the idle drops very very low, almost off, but then comes back up.

Is there anything else I can check or try or anything? Other than just replacing the fuel pump, of course, which I guess I'm going to do, but I have to wait until I am paid.

[Roach]

Kinda a noob so bare with me ust trying to help.n my vg in my z The drop in idle after a rev was fixed by replacing my fuel pressure regulator but my problem only occured when the motor was warm

[DoctorRobert]

I just pulled the fuel line and it is definitely getting fuel. When I pulled the line off, it sprayed gas out from the fuel rail (so hard that it got my shirt some) and when I put the gas line in a bucket and tried to start it gas came out. However, when the switch was just in the on position only a very slight dribble of gas came out for a second.

Like I said in a previous post, it had been running, but today I took it for a spin around the neighborhood and when I got it to 3000 RPMs once, the car jumped and the engine nearly died while I had the gas pressed and then just went to an idle after I released the gas pedal. Also, once when I pressed the gas pedal nothing happened while I was in first gear. So, I took it back to the house and when I shut it off it wouldn't start again, and then I did what I described above.

Any ideas now?

[DoctorRobert]

It also still cranks for a very brief second if I spray a burst of starting fluid into it.

[evildky]

if the pump works but you aren't getting fuel, it could be the injector relay, which is located inside the passanger fender behind the battery, there are 2 relays bunched together, one is for the fuel pump and the other for the injectors IIRC, thinking it was the green one but get a manual and verify

[DoctorRobert]

Are you talking about in the relay box towards the front of the car?

According to my book that came with the car, the fuel pump relay, the lighting relay, bulb check relay, air conditioner relay and inhibitor relay and the only ones in the relay box, and I can't seem to find any mention of a fuel injector relay. Of course, I know sometimes the books aren't exactly right...

Oh, and the car is running again today... this is driving me crazy!

[DoctorRobert]

Okay, I found the relay. Was just looking in the wrong place. When I unplugged it, it made exactly the problem I have had happen. Right down to the way it tries to start, but doesn't.

So, where can I buy another one. I have looked on the web, but none of the ones I have found look similar to mine.

I will try cleaning the contacts and what not.

[blackice280zx]

autozone/napa/local parts warehouse should have one if not time to go junkyarding if you were closer I would give you one of the 5 ive got laying around

[DoctorRobert]

Thanks! I didn't find one at a local parts place, but I did order one for $38 shipped from Atlanta Z-Car.

I received it today, and the car cranked up, but like I said before it's been running... off and on again. However, while I had the car running it shut off on me. Now, unlike the other times it started right back up, but also while it was running it nearly idled off, then jumped back up. So I have lost again. When it shuts off it doesn't do it as if it were slowly losing fuel and dying - it's just off like a switch was turned.

So, if what it did today was the same problem as before, then the EFI relay wasn't it... and I'm lost... again!

[blackice280zx]

try a junk yard maf mine was doing that when I first got it and I put a diff one in problem solved. also a fuel pressure regulator wouldnt hurt ether. They are cheap enough

[DoctorRobert]

Alright, I will try to pick one up today. What would be a fair price for one from a junkyard... also, does it have to be from the exact same kind of 280zx? Because I don't know where there is another 5-speed 280zx. The only ones that I know of in junkyards around here are 1980 models, both automatic, and one one is a 2 + 2.

Thanks!

[blackice280zx]

it wont matter as long as your not putting a n/a one on a turbo car or something like that. MOst I would spend would b 20bucks I have never spent more than that on one. But they sell on ebay for more.

[DoctorRobert]

That's good to know.

The only junk yard around here that has 280ZX's wants fifty bucks for one. But, at least one of the cars they have, have been sitting forever, and I have no clue if the AFM is any good or not.

The black cover on mine has obviously been taken off at some point, and someone tried to re-silicone it. The ones in the junkyard look like they have never been messed with - they've just been sitting for so long... especially for fifty bucks.

[blackice280zx]

if they have never been molested than I would go as high as 40 but have you priced one new? they are to pricey

[DoctorRobert]

Yes they are!

I will go back out there and see if he will go forty, and I will get the one from the most decent looking engine bay. Neither one looks messed with. I just don't want to end up with one - and then it turns out that the car was in the junk yard because that was the problem with it! If you know what I mean.

But I guess that's just the risk I will have to take if I don't buy a new one...

[DoctorRobert]

Well, I replaced my AFM with one from an '81 280zx that I found for thirty bucks, but the problem is still there. In fact, it seems to run a little worse for the few seconds it actually starts that it did before.

Any suggestions where to go from here?

[blackice280zx]

now it has me stumped it cant be anything real hard I will brain storm and try thing on a car that I am getting tomorrow that is doing the same thing

Question is it sputtering after about 30 min and then just turning off? If so that was a fuel pump issue my buddy had. It would pump fuel fine then just quit

[DoctorRobert]

With the '81 AFM meter in there it definitely ran worse than it does with the one that came on the car. So, I switched them back today, but it's just the old problem still - it just runs smoothly... that is when it does run.

No, it various with the amount of time it takes for the car to shut off. Last week, I drove the car across town - no problems. So far this week I haven't been able to keep it running for more than thirty seconds. It will always fire up for about 15 - 30 seconds after sitting for a day. Then after it shuts off it won't start for the rest of the day.

One thing is - it does start with starting fluid, but it's also getting gas. So, I'm stumped. Unless the injectors are only opening for a second. Would it run on starting fluid if it was flooding out? I wouldn't think so, but I just wanted to check... Oh - and it doesn't sputter. It just turns off like I turned it off with the key.

[evildky]

kinda sounds like the afm issue, if the afm sticks or has a deadspot the fuel pump will shut down, or the fuel pump could work for a minute then shut off but if it restarts immeadiately I'd look again at the afm