Intermittent '83

[aaalbedo]

I have an '83 that has left me stranded twice in the last two weeks, after 11 trouble free years. So I'm still way ahead of the game!

First time, it was behaving as if it was fuel starved; reluctant to accelerate, gentle missing at speed. Then it just quit. I had it towed home, and after a few false leads, I bench tested the pump (fine) but the contacts were filthy. Cleaned up the contacts, reinstalled the pump, cleaned up what I thought was the pump ground in the trunk (posted earlier that neither my '83 nor '84 has a left taillight ground, but they both have a stud on the left wheelwell with one wire that looks right... haven't done the continuity check to confirm). It started right up and was fine for a few days.

One additional note is that I hadn't driven at night for some time, but I did a few days before this failure. On that drive, low beams were fluctuating a LOT. Step changes so it looked like I was flipping back and forth between high and low beams every few seconds. I've since replaced the voltage regulator, but haven't had it running long enough to check for steady voltage. I won't have a helper for a couple of days so it will be tough to crank and measure voltage at the same time.

OK, now the real problem. It ran just fine for a few trips. Then yesterday I left home, and about 1/4 mile away I was accelerating, in 2nd I think, and it lurched twice in rapid succession; brief, but completely dead as if I'd turned the ignition off for half a second then back on. I got it up to speed OK in 4th, but then it died completely. There was no lurching in the higher gear, so it seems likely that this was the cause of the original failure and the fuel pump idea was a misdiagnosis. Cranks now but doesn't fire at all.

About a year and a half ago I did a lot of work on the car. Five injectors cleaned and bench tested, all new fuel, air, and vacuum hoses and new fuel pressure regulator. New module, coil, wires, and rebuilt distributor. But the pump is the one I bought the car with 11 years and 60,000 miles ago. Then the car sat for a year while we moved twice. I did some cosmetic stuff in May; new console, new Hartz top, buffed the paint from pink back to red. I drove the car daily for a month during this time and it ran great. Last week while I was fooling with the pump, I put in all new flexible fuel hoses starting at the tank, new fuel filter, and a strainer upstream of the pump.

Back to the problem. This latest failure can't be fuel; off and on was far to abrupt and complete. So it's got to be electrical.

It's a Colorado car so very clean, but yesterday I cleaned the two injector grounds on the plenum, and cleaned up all the contacts at the coil. I didn't suspect the injector grounds since both would have to fail then unfail simultaneously to kill it the way it did, but I had never cleaned them so it was time. Inspected the distributor, it looks fine. Cap contacts show minor burning but should be OK. Pickup wire looks fine; the pickup is just a year old as part of the distributor rebuild.

It's close to home so I went back in the wee hours with a timing light. On the first 30 second cranking try, no light at all. On the second, it was maybe 5 seconds in before I got a few pulses, but then it continued to crank with no light.

So maybe a weak coil? Other options are module, ECU, and double relay (I should note that I tested the relay in my '84 and it ran fine, tested the '84 relay in the '83 and it did not start but that was before I cleaned the contacts in the fuel pump, so neither test is definitive since the problem is intermittent). But I would think that any of these failing would be permanent and not give me any starts at all, or the flaky spark I see now.

AFM seems OK, I was fooling with that to test the fuel pump and it functioned as expected. But I didn't do a proper inspection. It seemed to be working smoothly.

Any thoughts? Next I'll test the coil against spec, then start swapping in components from the '84. The intermittent part is a big problem, though. Any other grounds I've missed? The cluster by the air meter looks fine, but I'll clean those first too.

Coil in the '83 is a year old Accel, module is stock and also a year old. Coil in the '84 is new from Vick's, Fireball maybe? And the '84 has a new Accel module. Just in case anyone has had issues with any of those components...

I was just getting ready to list the '83 for sale on ebay, but won't until I'm satisfied that this issue has been resolved. I had a lot of great years with it, but it is badly in need of paint and some other work. Just as I had completed most of the mechanical restoration and was considering my paint options, I happened upon the '84 as a distress sale, 42,000 miles and a beautiful bare metal paint job. Looking forward to the next 11 years and more with that one, but want the '83 to find a good home too!

Thanks for any insights.

Larry

[aj81spider]

May not be your issue, but I had a problem with my 81 cutting out and dying. Mine was more of an intermittent problem. It turned out to be the ignition switch. It's possible one (or more) of the contacts has gone bad on your switch.

[81SPIDERMATT]

do not know a whole lot about the electrical system for spark as have not had problems in that area ..yet ... but if you need an extra set of hands let me know ... I am not far off and would be happy to help out if I can

ignition switch would be a good thing to check though

and mine did sorta the same thing but it was a loose positive battery terminal clamp

[RRoller123]

Bucking can sometimes be caused by a sticking AFM door flap, or bad electrical connection to the AFM. This was the case on my 80FI, so I slowly and carefully sanded down the chamber to get the AFM flap to move freely, and did the modification to lower the swing arm under the AFM cap to get to new resistive material (there is a long thread/s on this topic here on the forum) and it never bucked again. Fixed the problem immediately .

[aaalbedo]

Thanks for all the input, and especially the offer, Matt! Nice to know of someone nearby and I may take you up on the offer when I'm doing more than just cleaning and swapping.

So I cleaned up the cluster ground by the AFM. Inspected the AFM and it is working smoothly, and the switch worked fine when I was testing the fuel pump last week. The wire clip around the electrical connection to the AFM was out of place so it wasn't holding it tight, but it did seem to be well connected. I also cleaned up the ground wire from the coil heat sink to the exhaust cam cover.

I tested the aftermarket coil. It was reading high on both resistances; 60K and 0.99. I doubt that was my problem, but I put in the original coil from the '84 that I removed back in March. It was reading in spec.

So all of the grounds and contacts were quite clean, so I didn't find anything that SHOULD have been my problem, but it started right up. Interesting thing is my timing light is still showing a flaky spark, even though the engine idles and revs smoothly. So maybe I have a bad light? Frustrating.

Anyway, I don't quite trust it yet and have yet to look at the ignition switch, so that's next before a test drive.

Thanks again for the input!

Larry

[bradartigue]

Last time one of mine did this the coil wire was bound up and the movement of the engine was making it pull out and in from the distributor cap. By the time I got home and realized what it was doing I expected to have a little baby distributor next to its mama.

[majicwrench]

Your ignition system is the most likely culprit, you need to get the timing light working well (while the engine is running!) so you can check it again once engine dies. I hate to see folks messing with wiring, grounds, coils etc etc unless they know what the problems really is, otherwise you are potentially just creating more problems.
If it dies again, or more realisticly when it dies again, go back and test for spark again w your test light. If no spark, check for power on the + side of coil, key on. If you have power on +side of coil, look at wires inside dist make sure they not frayed. There are ways to test your coil, pickup and module, but realisticly, the module is the highest failure item in there. Swap it out.

Keith

[aaalbedo]

I tested the timing light on the '84. Turns out it was a bad decision to power it from the coil posts; I thought with the chintzy little clamps that it wouldn't draw much current, but it pulled the voltage down far enough to make the '84 stumble, and the light was dead at idle and intermittent at 2000 rpm. So I connected instead to the alternator, and the light is fine. Tried the same in the '83, and it is now showing good strong consistent strobe (although it was not idling as smoothly as the '84). So it appears I have good spark after all on the '83, at least when it runs. It was also showing a good solid 13.5 V at the coil (timing light not connected) at idle. I still haven't run it long enough to see if the lights are indicating fluctuating voltage like they did on its last long drive before the first failure. Hopefully the new voltage regulator eliminated that fluctuation.

So maybe tonight I'll cruise the neighborhood after dark with the timing light and the spare module I picked up today.

Will refrain from playing any of that brown chicken brown cow music though; one distributor is enough for me, Brad.

Larry

[aaalbedo]

Well it's been running flawlessly since that last round with a few grounds cleaned up and the coil replaced; nearly a dozen trips so far with no cutout at all. I'm still keeping the timing light, multimeter and replacement module in the trunk though, because I didn't find anything that should have been the culprit. A waiting game.