Agreeing with Tony. Also, I bet those 2 other relays you replaced will work fine. It just so happened that you replaced them and the car cooled so the next time you fired it up the CDI was working again making you think it was the relay all along.

Hell, send out your CDI anyway to Bob and get it upgraded and purdy.

I stepped away for a few days, however I've tried out a couple things, and potentially uncovered more issues.

Order of steps and outcomes:
1. Battery: confirmed battery voltage of 12.XX, consistent with every other battery check on this battery.

2. Checked Fuses: visually evaluated all fuses, replaced a few: fuel pump (fuse, not relay), blinker fuse and parking lamp fuse. (Did not attempt to drive/start)

3. Coil: confirmed 1.2 ohms across terminals, 0 ohm reading from positive to center (!?). Reconnected battery, turned ignition on (not started) and received quite a scare...

4. Fuel Pump: when ignition was turned on to try to test coil, a loud hum/buzz was emitting from frunk and under hood, near fuel accumulator. Turned off ignition, then turned on again to confirm noise. Swapped out fuel pump relay, noise went back to quiet fuel pump hum like normal. (For fun, swapped back the initial fuel pump relay, and noise was back to quiet normal sound)

5. Starting: turned key to start, nothing...no starter solenoid noise/cycle, nothing. Turned key to off, tried again, nothing. Instinctively reached under key and pushed on wires while turning key to start, it fired right up. (could be coincidence?) While running, I pushed on wires, and did not have any issues with running. When it started, the starter was just as strong as always, and vehicle fired immediately, just as it always does.

6. Coil: back to checking the coil while vehicle is running, positive on positive terminal, negative grounded...received an 0v reading somehow?

I didnt go for a long drive, nor did the vehicle get up to operating temperature.

In addition to checking things like rev limiter/CDI...I guess I'm adding checking for ground faults to the list? Wire integrity between battery/key/starter? Anything else I'm missing? It sure feels like I've taken the first step in the rabbit hole and am quickly gaining speed into the abyss....

mzavada

So the car starts and runs good and then after some time when it is fully warmed it dies. As someone mentioned with my similar issue hook a timing light up and check to see if it starts missing. This will tell you if you are facing an ignition issue or not.

You should be able to drive around for 10 mins and then let it idle for another 5 to get up to temp. My issue would not show itself unless the temp reached ~180. A connection inside my CDI would break due to heat and cause a no ground fault killing the engine. Let it cool for 5 mins it would start back up, then die within a minute or so.

If it is fuel related you can hook a CIS fuel pressure gauge to your CIS and go through the steps of checking for correct fuel pressures.

I have a feeling that if it starts and runs good and then dies it is CDI related.

Haha...yeah, I've been known to overdo it with my organization. Doesnt always yield great results though!

Just another data point ... you mentioned you tried to measure voltage at the coil. With a CDI ignition, you will not be able to measure anything at the coil with a common voltmeter. The discharge pulse on the positive lead is very fast and only can be seen with an oscilloscope. It is only about 20 usec. wide. I responded to your private message earlier ... get back to me via email (bob@ashlocktech.com) and I will arrange to loan you a spare test 6-pin CDI unit. The test unit works great, but is so ugly nobody would ever want to keep it on their car any longer than necessary for troubleshooting purposes ... ha ha ha.

Fuel issue, tach will slowly drop to zero. Ignition tach will immediately drop to zero.

Yes, sounds electrical.

I would check the ground strap from the tranny to the body. Remove the strap/clean/replace if necessary. While you are there, check the starter connections.

Disconnect the battery first :rolleyes:

Not a ton of progress to report from tonight, but checked out/maybe ruled out a few things:

1. Trans/Body Ground: Removed and cleaned both ends and the surfaces they mate to. Looks to be in good condition overall

2. Starter: while in that vicinity checked to ensure that the starter was getting adequate power. Tested 12.12 v at top of solenoid.

3. Battery: tested at 12.12 v

4. Idle/operating temp: started vehicle and let run in driveway for 15 minutes . Ensured to replicate all accessories that were running at time of last stall. Vehicle ran fine the entire time, no stalls. Took the throttle high into RPMs a few times, with no ill effects. (Again, without load on the car)

Emailed Bob about borrowing CDI box and because I'm slow to process things sometimes, I concluded that borrowing it would tell me:

1. Stalls with his loaner CDI: its something else
2. It doesnt stall with his loaner CDI: its probably my CDI

Either way, now that I've evaluated a few things, replaced or adjusted a few things, I think I need to take it for a drive to see if symptoms replicate. (As another baseline)

Wish me luck tomorrow! Also, huge thanks for keeping all the comments coming. Dealing with CDI/Ignition isnt something I've done much so I'm learning from you all!

Check for tights connections under the dash of all the round wire harness plug-ins.

I hit a bump at 65 and the car completely quit like yours. The solution was pushing in one of the wire harness plugs for the ignition switch.

My vote is fuel pump. It backfired and died. Sounds to me like fuel pump.
Tony

So did it stall at the 15 minute mark?

When I did my warm stall tests, I timed it two separate times. The first was 21 minutes and the outside temp was ~85. The second time took 28 minutes and the outside temp was 77. Good luck on the next run. Pay attention to the temp gauge. That was what helped my zero in on a component failing to function due to heat, the CDI.

You've checked the battery voltage but have you checked the alternator output when the car is running? It should be in the. 13.5-14.2V range with all accessories and lights off.

I've been keeping an eye on that area too. I've triple checked the connections and as stated, pushed on the wires both before starting/while running. I'll continue to keep an eye on that area while I sort through this! Thanks!

It did not stall at the 15 minute mark last night. I turned the car off at that time, mostly because it was getting close to 10pm, and my neighbors live pretty close to my idling car noise. (thankfully they are cool)

My commute is consistently 10 minutes each way, and the times the car has stalled it has been around the 5-8 minute mark of my commute. (guestimating)

Temp during last stall during commute was in the low 70's, last night with no stall was in the low 80's. Will be continuing to pay attention to ambient and engine temp during this. In an attempt to determine if its the CDI doing the hot stall, I'm planning on bringing a bottle of compressed air to blow on the CDI to see if it speeds up the restart.

Great reminder, I checked it during the first drive of the year in early April and it was in the high 13v...did not check last night/since. Will do when I restart. Thanks for the reminder!

Actually...now that I think of it, that would cause the car to stall, but it wouldnt explain how when it came to a stop, I turned the key and the starter turned just fine, would it?

In other words, after the car stalled and came to a stop, the starter engaged, but engine would not fire.

Update from my first decent drive since the last stall:

Drive time: put in over 30 minutes total drive time, and about 5 minutes of idling time before heading out for a drive. Similar speeds/variables to when the car stalled last time, except I wasnt on the highway. (But still got to about 60-65 MPH) NO STALLING! Air temp was around 85 degrees and humidity was about 4,000 percent. (kidding)

Aside from a bit of protest when it first started, all seemed OK. The fuel pump did seem a bit louder than usual, however I am wondering if I just am hyper focused on anything being out of the ordinary and 'hearing' things. (Will obviously keep an eye on it) I have another couple of 'confidence' drives planned over the next two days and will update when I have something more.

You are absolutely right. There is more going on.

Not in my experience. At idle, it might sputter and die but at speed it'll be a different matter.

The fuel pump in my 86 (yes,I realize it's not CIS) died at speed and it just shut down immediately exactly like the OP said. In this case, it absolutely was the fuel pump and again, behavior was the same.

I am experiencing a problem somewhat similar to mzavada and I eliminated the possiblity of the fuel pump by removing the FP relay and using a jumper wire to keep it energized.
When the vehicle quit at speed I just coasted to a stop and did not touch the key.
I checked and the FP was still operating which would leave me to believe my problem is electrical (ignition).
But I've yet to find the solution.