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stumped on L28 n/a motor problem... need help


ZXR_KiD

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ok this just happened today the first time and myself and my father completely stumped.

in my stock (for now) '79 280ZXR

going to work this morning about 10 min into the drive I got off the freeway and got stoped at a redlight... within a few seconds the idol droped to a putter and died. I attempted to start it back up but it wouldn't fire. after sitting for a couple minutes the car fired but only ran for a few seconds. about 5 min later I started it back up and drove it to a parking space.

 

8 hrs later I returned to the car. it fired right up, ran fine. drove around the lot no-problem, so I get on the highway with my father following me and drive home. no sooner than I parked in my place the car puttered and died. same as before I let it sit for a few min and it started right up, but only ran for a minute or so.

 

with this information I can only assume at this point that it is somehow heat related, however it isn't acting like or showing any sighns that it is overheating.

I've had the car on the road since late feb and have never had a problem like this. my father (who has had a '76 and 2 '77 280s has never seen anything like this, however I am pretty sure the head is not healthy as I have not rebuilt the motor yet, and the rubber diafram in the fuel pressure regulator seems to have rotted... would this be causing these stalls?

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Guest bastaad525

I had a problem exactly like that in my '81 ZX. For me, it ended up being the little black box on the side of the distributor (ignition module I think it's called?). I've actually had a similiar failure in a different car (plymouth champ). Same symptoms both times. Car would start and run fine, then as it heated up it would die. Try to start it again and it would either run for only a few moments or wouldn't start at all. Wait til it cooled off and it would start right up.

 

If not that I still agree it sounds like something related to heat so it might be something like your head temp sensor... any things that are specifically affected by heat. Maybe even your ignition coil?

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I had a similar prob on my 77 280z. It turned out to be that the water temp sensor (on the thermostat housing) for the ecu was barely on, due to a cracked harness connector. I just wedged it on there realy hard and it has worked since (I realy should get around to buying a new connector... oh well the lazyness kicks in).

 

What happened was I was going to an on-ramp in third gear accel. and the engine started to sputter and as soon as I put in the clutch (emergency reflex) the engine died. I had it towed to my friends house which was closer than my house and the next morning the car started up just fine. Then after a few hours of trouble shooting I found out exactly what it was. (loose temp connector)

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we just went through all the fuel lines and checked pressure, in doing so made the discovery that the fuel sample we ended up draining was aprox 1/8th water (speedway gas for ya) we can't find anything elese visibly wrong with it so we added HEET (fuel line anti-freeze/anti-water solution) and we'll know in the morning.

 

I really hope this is the problem since this is the only car I have to drive.

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Remember "Check the basics". I would think(i have my own shop, diagnose all run problems, been doing it for alot of years) Ignition module-car would die on freeway or where ever. Fuel pressure(fuel pump)-Same. What clues me is what you said about your fuel pressure regulator(ruptured diaphram). Sounds like the car is flooding when coming to a stop. If it's ruptured change it. A good way to check is see if the vacume line has gas in it. Or make sure airflow meter is not sticking! Stick your fingers in it and make sure it returns to a closed position. Nice even movement. Good luck let me know!!!

JOEY

P.S. As for bad gas... I would think you would have run problems. (miss fireing, back fireing ect...

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well today the car did it again and I checked the little box by the distributer... BINGO, had a loose wire, shoved it into place and drove for 3 hrs no prob.

 

yes I have found myself a job, I now am a lot attendant at Bachman chevrolet, so I get to drive bassically anything. and after transporting one from the prep-lot to the dealer I don't like the corvette Z06s they just don't sit right, guess I'm always gonna be a Z guy :) today I get to drive the 2k2 lancer Evo that we have in the used lot... it's the only thing we have that I wouldn't mind having for myself.

 

and I have filed for enrollment at southern but it will be atleast 3 days before they can accept or deny me as I have to interveiw with the principal who is out of town

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check the fuel pump!!!! I had this very same problem happen to my 1983 280zx. the fuel pump was so old and worn that after running for a while, it would heat up and without constant air moving around it (i.e. while driving at 20mph+) it woudl lock up. I would have to wait for about 20 mins for it to cool down before it would turn on again, or I could throw some cold water on the fuel pump itself and the car would start right up. odd as it sounds...... I replaced the fuel pump and have had no probs with it whatsoever....

 

Mack

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hmmm... I just changed plugs/wires/cap/rotor about a month and a half ago, Auto Zone generec cap/rotor/wires and Champion plugs.

 

I'll look into that tho, a mechanic at the dealership where I work had a 77 and told me his did the same thing to him and it turned out to be the filter on the inlet of the fuel pump was cloged. so I'm gonna look into that too.

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I have seen this before but not on a Z. Same symtoms as you have. Turned out to be the fuel pump was loosing its prime. So on the highway when it needed more fuel it would loose its prime and then die. Let is sit for a while and it would run again but not very good. If you have a fuel gauge handy hook it up and drive the car around and watch you fuel pressure when this happens. If its dropping off then you either have a clogged fuel filter or a bad pump.

 

 

Guy

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Sounds fuel related. Check what 80LT1 said, then check your tank vent system. If the vent to atmosphere is plugged it will draw fuel only until the internal vacuum in the tank over powers your fuel pumps suction. Try running with your fuel cap loose.

Just a thought.

Bill

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I've never seen an L-series run as well on Champion, Bosch, Autolite, Motorcraft, etc. plugs as it will on NGK's. Yes there is a NOTICABLE difference in changing to copper electrode NGKS over any of the above. The plugs won't solve the problem you are having, but they will solve others that will creep up. BPR6ES, BPR6EY-11 or non-resistor type plugs of the same heat range and size are very good in NA L-series engines.

 

I've seen this problem on ZX's, and it has been fuel pump, ignition module, or simple contact corrosion in those cases. It's a tough one to nail down over the web, I think you are going to have to get in there and test a bunch of things to see for yourself.

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Gads guys, elimination and troubleshooting of this problem (at least the ignition module portion of it) is so easy.

 

Buy a can of freez-it.

 

When it stalls, pull the center terminal wire of the distributor, and have someone crank it to see if you have a 1/2" spark to ground.

 

If not, pop off the cap, spray freezit on the inductive pickup in the distributor. Put it back together and check again. If you have spark now, it's the reluctor, if not, then...

 

Spray the hell out of the module and crank again---iof it starts sparking it's the ignition module.

 

If you have spark at step one, when you first pull the center terminal, then it's not electrical (spark generation at least), and don't waste any more effort along those lines.

 

Bad black boxes are common on ZX's. Very common. Originals are usually good for 200K+ miles, but time and heat take a toll, and eventually components fail. Nothing lasts forever, save the Nissan L-Block...

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I finally have the next 2-days off so I'll get it torn into.

being a "yet-to-be-rebuilt" junkyard car I expected problems from it but I thought I knew what to expect, and thought I'd be able to figure out what happens that I wasn't expecting but this one has me really confused.

 

thanks again for all your help guys, I'll post again when I know more.

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Mi amigo. This s problem plagued me for a year straight. Finally installed a fuel pressure gauge in my car, and raelized that my fuel pump relay was over hearting causing it to turn my pump on and off. I ran a hardwire to a switch inside witha fuse for a while with no problems Finally put in a new generic relay. Try running a hot wire to the pump and see if you have that problem again.

-Ed

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I'll look into that tho' date=' a mechanic at the dealership where I work had a 77 and told me his did the same thing to him and it turned out to be the filter on the inlet of the fuel pump was cloged. so I'm gonna look into that too.[/quote']

 

Umm.... I don't remember there being any kind of filter screen in the pump inlet? I could be wrong

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  • 2 weeks later...

ya I know I'm a little late on this post...

Everything has been eliminated leaving that FPR,( yea yea bring out the "I told ya so's)

 

EvilD, do you have a spare lyin around for the N/A or does anyone know if the turbo FPR would work?

Next Q: if so, how much would you want for it?

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