SteveG

You checked but I don't see that you changed any relays. I have relay tester, but an intermittent problem would not necessarily show.

Does this happen at any particular time? like when it reaches operating temp? That would point to coils, wires, things that might be heat sensitive. Otherwise this sounds like ign switch.

I wonder if there is an intermittent injector wiring problem?

Cutter's fp gauge tool sounds helpful too, would be great to eliminate fuel from the possibilities.

Indy Rev

I have swapped out relays with known good ones. I have not bought any new ones yet. I have a FP gauge on the fuel rail..."not permanently but for testing" and FP does not drop. I checked this the first time it died at the side of the road.

This problem does not happen at any particular time. I've driven the car cold and it died, I let it warm up and it died. I drove the car to the store and home with no issue. I let the car idle for 30 min and no issues. Yesterday I drove the car 2 miles before it went out. on Sunday I didn't even get out of my neighborhood. Its very hit and miss.

FLYVMO

Since you're having weird electrical indications (bouncing fuel level) I would replace the ignition switch, especially if it is original. Second, a failing LH computer will cause the symptoms. Do you have a spare one to swap out to test with?

Cheers!
Carl

Indy Rev

I dont have a spare LH and everyone I know has an S4.

I think Ive narrowed the bouncing fuel to the sender. If I knock around the trunk I can make the needle bounce. I am planning to inspect it tonight.

I will see if I can get a test ignition switch from someone to rule that out.

FLYVMO

Sean,

I have a spare LH brain from an '85 32-valve, which should be able to run your 86.5. I tested it in my 86.5 and it worked perfectly. I can lend it to you after you change the ignition switch, which I HIGHLY recommend if it is original, because it WILL eventually get you stranded. Happened to me both in my'80 and '86.5. Even if it is ultimately not the culprit, it will be well deserved preventative maintenance. Post back your findings and I can send out the LH loaner computer to you if the ignition switch does not fix it.

Cheers!
Carl

Indy Rev

Thanks Carl.
As I sit here and ponder the car and its behavior, a bad switch really could be in play. Ive had so many other culprits of the car not starting, vac lines, FPR, bad grounds, etc...that I really didnt think much about the switch and how the car will continuously turn over and I have to listen for it to catch then release the switch for it to start. You kinda get used to the small stuff when fixing the big stuff.

Looks like Ill be ordering a switch.

FredR

Sean,

You could test for my favorite- check to ensure the battery is securely fastened down and that non of the cluster of connections on the positive terminal is temporararily shorting on the lid- does the cut out happen when you hit a bump by any chance? Look for signs of arching on the lid adjacent to those connections- I always insert a strip of sheet rubber in there[ a piece cut from some inner tube]

Always eliminate the silly ones first.

regards

Fred

hans14914

Thats what I was thinking. Did you check the main battery terminals and ground strap and points in the spare tire area. I have seen batteries welded to the lid when the wrong size was installed and without a clamp. If there is any scorching on the lid, that could very well be the culprit.

I havent seen it personally, but there are pictures on the forum of bad ground straps that look ok - when the insulation is removed they are toast. You may want to test impedance between the negative battery terminal and the body the next time it happens to see if the strap is to blame.

Indy Rev

Ok Im not sure if I should be happy about this...but she finally died while idling in the garage. She was idling for about 4 mins while i was checking the batter top/lid and connections. Even going so far as to shake the battery...that's not it. Then while i was looking into why the trunk latch button/pull doesnt work she just died...again like someone turned the key off.

Observations after death. Fuel pressure was perfect, fuel gauge didn't move and was reading properly, in fact the car looked like i had just set it to the on position without starting. I turned off and restarted and it fired right back up. I had no other incidence letting it idle for 15 min while I continued checking other connections.

jheis

Once again, crank position sensor.

Indy Rev

I think I have a spare S2 reference sensor and looking at the parts # they appear to be the same. I will check it out when I get home.

If the sensor itself is bad wouldn't it not restart? I'm not questioning, just trying to understand its operation.

BRB-83-911SC

My car displayed the same symptoms - it would shut off as if you turned the key off. It did this 4 or 5 times when rolling up to a stop light or just idling, and once while driving down the road. It started right up again, except for one time when it needed about 10 minutes before restart. Finally, one day it was dead in the garage, and wouldn't start at all. During the no start occurrence, I noticed that when cranking the engine, the tach did not move at all (no registration of the cranking revolutions). First occurrence of the random shut off until the eventual no start was several weeks.

A new CPS cured it, and the issue has not recurred in the past 3 years. My CPS connectors were in great shape; just an internal failure of the CPS.

If you have a spare CPS, I would give it a shot, if it is known good. Otherwise, a new one isn't a whole lot of money. Not saying this is your problem, but it certainly is something I would want to rule out.

Indy Rev

Thanks Brian. Yeah the 1 I have is brand new. I had forgot I even had it till I looked one up today to purchase and realized its the same part #. Im planning on tearing into it tonight and see what happens. A little WD40 soaking before I start the grill and hope it comes out easily after dinner.

jheis

On my '89, I discovered that the plastic part of the 3 prong connector had disintegrated - leaving the 3 spade connectors exposed and allowing them to ground/short out intermittently.

Car would die at 70 mph on the freeway - or when I came to a stop sign. Sometimes it would restart immediately - sometimes not....

gronkX

I was been having the same issue with my '86.5. The CPS was replaced 2 years ago, but last year it would simply stop running seemingly at random, and then start back up as if nothing happened.

I'm going through all of the grounds this spring (in fact, just got in from the garage) so I'm really interested in what you find.

Is there a way to test the ignition switch, or at least verify whether or not it's the problem if the car isn't running?