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Holy ****! New problem with 1979 280ZX-R - Cuts off going down interstate!!

4083 Views 29 Replies 14 Participants Last post by  raszxr

I finally get car fixed and now something new!

Going down Interstate about 70 mph and car just cuts off. Doesn't sputter, or give any sign. When car slows down enough for engine lights to come on, I can turn the key and restart it and drive with no problem. Did it every day this week, but did it twice today. It acted like it didn't want to start this afternoon though.....after a few minutes it finally did and I got home okay.

Mechanic's first thought was another bad igniter on distributor (this already is the third distributor from O-Reilly Auto Parts) .... other thought was screen in gas tank getting clogged and when engine cuts off the pressure is released and debris fall and there we go.

I tend to think it's electrical because it doesn't sputter or give any sign it's a lack of fuel issue.

YOUR thoughts!???!?
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while doing all the other stuff that you had problems with did you get the battery load tested and make sure your battery cables are good? Check the fusible link box for something loose there. Be sure you have a good ground from the battery to the frame and are not attempting to ground thru the starter as that isn't a reliable way to ground and Z's with low voltage have all sorts of gremlins. could be a faulty igntion switch. only way to eliminate fuel as an issue is to get a fuel pressure gage and mount it in the cockpit so you can see if anything is awry there. possible something wrong in the fuel pump relay circuit.
I did a search and read something about GM HEI swap....searched that and couldn't find anything...what is that?
battery is new...cable ends were cut and redone because they were corroded...all connections were checked by mechanic....I will check the other things tomorrow....Thanks for your input Roger!
Check the solder joints on the ECM board that plug into the main harness.

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this is kind of a weird issue, isn't it? well, it could be many things (gremlins) but it makes sense to start troubleshooting the small stuff first.
checking the fuel pressure is a good idea, which has already been said. i would also check your fuel pump relay the contacts and solder joints.... (i had a similar issue with my '80 zx a few years back - it would start and then just shut off, but i would be able to restart it after that. turned out to be a loose solder joint on the fuel pump relay)
you really want to weed out fuel, so you should start checking that system first. i know on the zx, you can take out the pickup mesh in the tank and clean it, unlike on the 240s and 280s. something else (which i just read a few days ago) has to do with your oil pressure. i guess they installed a cutoff switch that is tied to the fuel/ignition system that activates when the oil gets low.... was happening to a guy on here that said his z would just turn off while going down the freeway while making a fast, sharp turn. something maybe you should check.

as far as the electrical goes, could be anything. but electrical components either work or they don't. do yourself a favor, if you have been buying multiple distributer parts from o'reilly's it may be a better idea to get those kinds of things from Napa... their parts are O.E.M quality. little more pricey, but more reliable (i think).

good luck on your troubleshooting. listed to what the others here have to say, there are some real knowledgeable guys that know this stuff through and through.

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bonfire79 said:
as far as the electrical goes, could be anything. but electrical components either work or they don't.
Not true.My ECM issue was intermittant.Took awhile to find it.Since my ECM is on the kick panel,the door slamming or a bump in the road would connect or disconnect the joints.Or it would die and just sitting there, it would light right up when i hit the key.
I have this same thing happen to me in my first Z. It was a 78. I would be driving down the highway and with no warning of any kind the car shut off. I got it back to my shop and with the car running I was fumbling around with electrical connections in the engine compartment. I reached across the fusable links and my arm bumped one of them and bam, cut shut right off.
Found it by freak accident, but pulling them off and tightening the female ends of the connectors with pliers did the trick.
I will let you guys inow what I find out...I have four days off so I'm going to try to troubleshoot myself....if that fails I'll turn it over to the mechanic...at $60 an hour...ugh!
Try to isolate it further if you suspect electrical is causing your engine to shut down. Check and see if it is also affecting the other things in the ignition circuit (ie: radio, wipers, turn signal). Don't rely on your headlights. They're on a seperate circuit. If those things are dead too, then most likely it's not going to be a fuel problem.

You should really get a pressure gauge hooked up to the fuel line. It will help you isolate if it is a fuel pickup problem that the other mechanic suspects.

It's interesting that you say that the car will restart only when it slows down enough for the engine check light to come back on. You also say that this is your third distributor in the car. You can check your mechanic's suspicion and troubleshoot the ic ignition unit. The procedure is outlined on page ee-24 of the factory service manual.

What ever you do, don't start start a wholesale replacement of parts without trying to isolate what the problem is.
I'm thinking yours has the e12-80 ignition? If so, I have had the exact same thing happen to me - it was the ignition module starting to act up. When mine would die I'd just push the clutch in, cycle the key, pop the clutch and then I'd be good again...I never had to pull over to the side of the road. Anyways, the module is on the side of the distributor. Now you said you've replaced the dizzy but that doesn't necessarily mean the module, so if anything, search on the forums on how to test it...I just replaced mine without testing, but it fixed the problem.
I just remembered, the radio and all stays on when it shuts off. It's so subtle it just starts slowing down and the gas pedal is dead...I did pop the clutch the first time to restart it, but it would only restart after I've slowed down enough for engine lights to come on. All of the other times, I just turned the key while rolling, clutch in, it started and I rolled right back onto the Interstate. However, the last time (yesterday afternoon) I actually rolled to a stop and had to try for a few minutes to start. It was just the starter noise the first few minutes meaning it never really fired up at all til the end. I do have a fuel pressure gauge under the hood tucked in but still connected. I will position it by the windshield wipers so I can monitor it.

The "module" on the side of the dizzy?? Are you talking about the "igniter?" That is what was bad the last time..it was working on and off. Anyway...I'm on it!
The problem with my 79 was the pick off coil inside the dizzy, that feeds a red and a green wire into the top of the ignition module. The crimp spade connectors had sharp little brass thorns left from the crimping process, and the brass thorns from one was piercing the insulation of the other, and intermittently shorting out the coil. No pick off pulses, no spark. Sometimes I could instantly restart it, either with the key or by downshifting and popping the clutch. Sometimes it had to sit for a few seconds, or a few minutes.

I fixed it by wrapping an inch of black electricians tape around the crimps on the red and green wires, and never had that problem again. For a while here on ZCAR, several years ago, it was a very common problem. Still gets asked every other month or so. It might not be your problem, but it is quick, easy, and costs nothing but time to check it.
I just replaced the ignition module on my 76. They are inside the car for 1976 but perform the same function as the E12-80 on the distributor. Similar symptoms as far as the problem going away just by turning off the key, but my car did not lose power completely, it just got lots of crazy extra firing. The tach needle jumped all over and it started missing after high rpm activity. Turn off the key and restart and it goes back to normal running. My Schucks-bought Autolite-brand remanned alternator went bad at the same time and I think it over-volted the module, damaging it.

Here are a couple of links to the GM HEI modification. The GM module performs the same function as the E12-80, but is cheaper and more abundant. I have not done it because I had a spare module but will be doing this next time.


One with pictures - http://www.sonic.net/~kyle/ztech.html
Monitoring your fuel pressure is a great idea here! But if you're fast enough, you may just quickly look under the hood when you stop and you'll get youor answer, I like having a permanent fuel presure gauge to look at JUST to know when I really NEED to change a gas filter. Norm K.
Sounds like you've got the electrical isolated beyond the fusible links and ignition switch. If your fuel pressure is still good when the engine dies, I'd say you've should start to look at the distributor, coil, high tension wire areas.

Or you can just jump ahead to what you are calling the igniter. Others call it the ignition module. The FSM calls it the IC Ignition Unit. What ever you want to call it, it's the module mounted on the side of the E12-80 distributor.

I'd be a little suspicious that the module is bad if you've replaced it more than once before. Especially if the dizzy is still the same and you're experiencing the same symptoms with different modules. I'd want to look at the area of the pickup coil in the dizzy as a potential problem source.
2nd monitoring fuel pressure ( and a filter change ) ..
Kim, can you drive the car around all day off highway with no issues... is it only when your driving 75 + on the highway??
If you can start right up after an issue like that...my first " guess " would be more fuel system related than ignition...But you have to start somewhere..

What to address first? If you are getting your dist from OR, you are probably getting a rebuilt from Cardone. So is AZ and Napa. While the above statement may have held true 20 yrs ago or even with a later car, these parts have pretty much dried up so relplacements are coming from the same place...unless you want to pay $500 from nissan.

Usually if it is the "IGNITION MODULE" on the side of the dist, it runs fine til you come to a stop, then it cannot sustain an idle and will not restart until it cools.

Stay away from a GM conversion. At this point it is hjust another headache.

If you take off the hose from the tank to the fuel pump (crimp it first to keep gas from pouring all over), and look inside that inlet, there is a small cone shape mesh filter. Look for signs of crud. You can also install a Fram G4 filter in that spot, but be advised that by now the end of that hose has been stretched to 1/2 inch and the filter is more like 3/8. I put mine in for about 6 mos to determine all was well then removed it.

It is possible that there is crud in the take that shifts it way to the pickup tube.

Is it possible the coil is not secure and grounds out?

Lot of good ideas above.
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OK...so if I'm going down the road...it cuts off...I engage the clutch...turn to key to off and then back on...won't my steering wheel lock if I turn to off??? I would wreck! I should probably just pull off and then restart, huh...I will be checking the car out tomorrow...seeing if I can identify any issue...hate to keep throwing money at it at through a mechanic, but if I need to I will.
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