Hey all,

So I have been plagued with this issue for the last number of years, and the fact that it is intermittent, and if I am patient it always comes back. I have left it on the back burner of my too do list for my 91 Z. My car is now garaged all year round, but in the last maybe 10 years it did spend winters outside, and even summers for some of those years. Before that the car was garaged for about half the year, but it was my daily driver and was driven all year round in the Chicago land area, so it has certainly been exposed to salt and rain, but is not anymore. Only occasional rain if an autox event dictates it.

What is happening is that intermittently, when I put in the key, turn it to on, hear the fuel pump prime, then go to try and start the engine, I loose ALL power, dome light, all dash lights, the buzzer that says the keys are in the ignition, everything. The whole car remains dead for anywhere from 10 seconds to a minute or so. Then randomly everything comes back. Some times this will happen two or three times before I am able to get the engine to actually crank and start. Once the car is started, I have absolutely no issue.

At first I thought it may be the fusible link, but If that was the issue I would have thought I would have more issues than just this intermittent starting issue, and would it make sense that I loose all power? I have also been unable to identify which specific part this is, to reorder or even inspect mine.

I also have considered that it could be an issue with my starter solenoid either shorting or sticking, but it is strange that it can remain dead for anywhere from 10 seconds to a minute. This starter is a performance mini starter I put on maybe 15 years ago. And it has been exposed to some weather.

I considered it could be an issue with my key or the ignition cylinder, but jiggling the key or switching keys, I have two, doesn't seem to make any difference, but I don't usually have time to run and try the other key...

I did find that the connector below seems to have some thermal distress in the connectors, IE melted. I'm not certain what this connector is for or if an issue there could cause my symptoms, I tried to bend the contacts to make more positive connection and filled up each connection with dielectric grease and put it back together. I also looked online to find a replacement connector, and was unable to find one, if someone could point me in the right direction, I would like to replace it regardless if possible.




What are your thoughts??? What can I try, or look at more closely? I have done a lot of searching but never found another thread with the same issue. If there is one out there that I missed please link me!

Thanks All!
-Eli

 

The ign switch (not the key cylinder) under the dash may have a problem. I'd look there. I'd suggest taking a test light with you to see what actually does or doesn't have power or ground when it fails.

 

Regarding the Electrical Connector that you found with a melted Section/ Terminal...
That is the C145 Electrical Connector, and I have some information on it, via the Posts I made in the Hyperlink below:
LINK

I do not know if any Wiring in your car has been modified, or had Aftermarket Accessories added on...
So I do not know if the Connector C145 has to do with the Intermittent Power-Loss that you have experienced;
But it is part of the various Power Distribution Circuits...
and if modified with another Accessory, past the Maximum 46Amp/ Terminal Rating of that Connector (resulting in Melting) could be involved in the Power loss.

The Components which make up the C145 Connector are still produced and available.
If not so inclined to DIY a C145 Connector, I can direct you to a Business that can offer you some form of a replacement Pigtail.


Note: Dielectric Grease is not a "Conductor" to be used as a method of improving a Connection (following along that line of thinking, it would create one form of a Short-Circuit).
The properties of Dielectric Grease in that regard are rather interesting.
It much more so Insulates than Conducts, and should be used as a method of preventing Moisture Ingress.

 

I can't comment on the C145 connector as mentioned by vorteciroc but I did have the identical problem as yours. Everything else including the fusible links at the starter checked OK. I did however change those just because... In any event, as aliceempire has suggested looking into, I skipped over the test and went right to changing out the ign switch located at the base of and on top of the steering column, 35 years is a long time to be in a car. And the car has been flawless since.

 

My first thought is a bad battery cable terminal connection at the battery.

Or, even a bad connection inside the battery.

 

Pull the headlights on and try the starter. If the power and headlights go out and stay out it is probably a bad cable or dirty connection in those main cables.

 

It's a bad connection somewhere in the Big Red Wires that feed battery to EVERYTHING in the car. Any of the places mentioned above can cause it. When it does it, STOP, and get out your meter, and start measuring the voltage on those wires, until you find the point at which the 12V disappears. Start at the starter; the fusible links can do this if they're part burned through or if they have a bad connection at their ends. Next, the Big Red Wires go to C100 (the bulkhead connector, below the brake booster); those terminals can easily develop bad connections too. They pass into the cabin there, then there are splices in the harness that route power to the fusebox, headlight switch, ignition switch, etc. Basically to every point inside the car that gets fed unfused battery.

The ignition switch and its wiring can't cause the headlights to quit working, as an example of things that CAN'T happen; power to the headlights doesn't go through the ign sw. It's not the starter solenoid for the same reason, although it could be that the big nut for the batt cable is loose (that's one of the ends of the fusible links in the Big Red Wires that I mentioned above).

That connector in your pic is definitely smoked but I can't tell what it feeds. But I doubt it's "the problem". You absolutely should replace both halves of it, it's probably causing something somewhere to flake out, but I doubt it's the root cause of all the rest of this.

A copy of the FSM for your car would be a big help.

 

If you have disconnected the battery cables several times
the internal batt. terminal crush tabs are flattened out.
So now the cable head screws are seated too far into battery lugs for good contact.
So sometimes you lose all power to car.

Cure for me was to grind off a mm or 2 of the terminal cable hold screw so it dont
seat foo far into/past the battery lugs for good contact.
With some batteries the screw will pierce the batt. internally and the acid will leak out.

 

Can you or someone link me to the part itself online? I searched and am not seeing it. If you have a picture of where exactly it is, I can certainly take a look at it.

 

The wiring in the car is pretty stock and I'd say in decent shape. I have added an ignition box but it has it's own power wire coming from the battery. I have a sound system but again, it has it's own power cable.

given the wiring schematic on the link you provided I totally agree with you it is the C145 connector, but it looks like it comes out of fusible link D which looks ok from the outside at least, and supplies power to my cooling fans, fuel pump, fuel pump relay and ECM. That said everything goes out when it does, not just those things, like the dome light, dash lights headlights, even the buzzer for they ignition letting me know my key is in. This makes me think while I should replace the connector, I don't think that is my cause... I could use your help thought, I have no problem with a diy connector, I think I even have the pin tools, but C145 doesn't find any parts for sale on google, what should I look up to find the replacement components for that connector? If you have a link that would be even better. Think I can just replace the plastic housing, or should I replace the metal connectors too?

I do understand the properties of dielectric grease. I honestly just squirt some in each connector I take apart before putting back together, then I don't have to worry about any connection issues from oxidation or moisture getting into the connector causing corrosion. I guess with the rubber seal it is less critical, but I don't think it can hurt.

 

That sounds promising! Have a part number for the ignition switch you replaced? Any pictures of exactly where it is or what it looks like? Do I just drop that lower dash panel on the drivers side and it is right there? Since you say the fusible links checked out on your car, I think the ignition switch would be a good first thing to try, usually they're not too expensive... I hope!

 

Regarding the rest of the discussion with the battery connections, or cables, or even fusible links now that I think about it. I'll keep my mind open to it if the ignition stitch doesn't help. But the more I think about it, It happens suddenly when it happens. Cuts out suddenly and completely, and resumes suddenly and completely. The lights never dim or anything, its just totally off for a few seconds, then suddenly everything is back. I'm also pretty sure I hear a quiet click when the power cuts and when it returns... This makes me think it is some sort of switch or relay sticking. Something that is maybe spring loaded so it is either contacting or it is not... Now I just need to find this ignition stitch Rock auto doesn't seem to be able to direct me to it... If no one can help me out I may just have to pull the lower dash panel and see if I can find it then bring it in to find a replacement locally.

Is this the "ignition switch" we are talking about?

More Information for STANDARD MOTOR PRODUCTS RY544 (rockauto.com)

 

I can 100% PROMISE you this with all certainty;

If things like your dome light (which you mentioned in post #1) loose power when the failure happens, it's absolutely NOT your ignition switch. Why am I so sure of this, you might ask? Simply put, your dome light is not, in ANY way whatsoever, connected to or controlled by, your ignition switch !

You have the classic symptom of a bad connection at either the battery, the starter solenoid (positive connection) or the engine block/body ground point (negative connection) Somewhere in what I described you have a corroded connection, it very well could be in the battery wires or terminals themselves. A few quick checks with a meter when it's acting up will quickly pinpoint which connection is being lost.....

 

Electrically thinking you do make a valid point. Do you agree thought that the sudden way it cuts out, then back in seconds latter sounds different than just a bad connection? Could it be a sticking starter solenoid?

I guess to be sure I need to remove clean grease and reconnect all my battery cable and main ground cable connections....

 

Well, little update. I went through and check tightness of my primary battery and ground cables at all connections. The connections at the starter seemed tight, thought I didn't like how tight the cable was as a result of going from the standard starter to a performance mini starter many years ago. I checked the ground cable on the battery, and on the body of the car, all tight.

Lastly checking the main brass positive cable bolt adapter thing, since I have other auxiliary connections connected there too. and it was actually a bit loose. I took it off to clean and grease it before reinstalling it, and found some of the threads to be missing, apparently I over tightened it in the past... I cleaned out the brass shavings, and tightened it back down as much as I thought I could get away with given the condition of the threads. I'll have to get another one of those if they can be bought on their own. I did make sure that there was no interference and the bolt tightens down far enough that it makes good contact with the cable connection. So far it hasn't happened again, but I'm still not 100% sure that was the cause. I'll update in another few weeks if it has happened again or not... It would certainly be nice if the solution was so simple...

 

Haven't had the problem again since I cleaned and re-tightened the above battery adapter. I actually bought a replacement but still need to get them swapped out...

It seems this solved the issue! I'll reply here if it returns...

 

I put in the replacement adapter I bought from Napa. Its hard to get a feel for how tight I can go without stripping it... The adapter is brass, and I'm not sure what the threads in the battery are, may not be steel...

Anyone have a torque spec for this thing?

New Battery Bolt I Got:
Battery Cable End Taps Long Battery Side Terminal Bolt For Accessory Wiring NW 785129 | Buy Online - NAPA Auto Parts (napaonline.com)

 

Issue still hasn't resurfaced since my last post, now in April of 2023! Seems like that was it!

 

Good news.

The threads in the batt are most likely lead. You can probably put something on the order of 12 ft-lbs on them safely. I wouldn't go too far past that. The nut can probably get 18 - 20 ft-lbs or so, but be sure to hold the post adapter still with an open-end while tightening the nut, and arrange the cables such that vibration and their weight and whatnot, won't loosen the adapter in the batt.

 

Seems you got this fixed, maybe this will be useful to future searchers. Most batteries that I've had on my 91 have been a 3/8-16 thread.

 

Thanks for the torque chart. It looks like something like 192 in-lbs (16 ft-lbs) for the nut on the brass stud and for the lead battery threads, aluminum is the closest shown, but I think lead is even softer... so something less than 143 in-lbs (11.9 ft-lbs).

 

The nut on that thing is fine thread (24 tpi).

 

I just had some uther significant drivability issues, and found a new ignition control module, seemed to fic the problem. Any chance something related to a failing ICM could have caused this problem?

 

So much for this being fixed, problem is back with vengence. Happens at least once sometimes 3-4 times when trying to start. Dead period seems to be longer too.

The more I think about it, I think it has to be something with the starter. I hear the sulenoid fire, then everything goes dead.

I think I'm going to try a new starter, they're about $140 and the one I have is about 15 years old, daily driven all year for its first 8-ish years, so things may be all rusted up... also have a small oil leak so there may be oil in the starter...

 

I still think, , , as I did back in 2022, that unless you've replaced both battery cables with new, the fault lies in one of your cables being corroded internally.
(as in, under the insulation where ya can't see it)

When it's acting up, a quick check with a voltmeter will show the fault......

 

It's really hard to test because of how intermittent it is. You're saying check for voltage at the starter end of the main power wire when it goes dead? I think that would have to be done from underneath and with my luck, if I lift the car up, it won't do it at all... When I lift it up to do the starter, I'll do a couple tests, and see if I can reproduce the issue...

 

To test it:

Wait til it screws up. WHILE IT'S IN THE ACT OF SCREWING UP, turn on a fairly high continuous load, such as the headlights. Probe all along the Big Red Wires at the connections, to find which connection has 12V on one side and 0V on the other. It's important that you do this WHILE IT'S IN THE ACT OF SCREWING UP. Like, be prepared at all times, and when it does in in your driveway, WITHOUT GETTING IT TO WORK FIRST, perform this test WHILE IT'S STILL IN THE ACT OF SCREWING UP.

In case I forgot to mention, the only way you're EVER gonna find it, is to test it WHILE IT'S IN THE ACT OF SCREWING UP. If you aren't sure what I mean by WHILE IT'S IN THE ACT OF SCREWING UP, lmk which letter of which word is hard to understand, and I'll try to help you get it.

 

Haha, I totally understand I have to be checking voltages while it's messing up... it's just hard because most times it happens the car is on the ground and I can't get to most important electrical connections.

What are other quickly testable accessible points that should have switched or always hot 12v?

Even if I pull the lever for the lights no power goes to them, I can tell you that on account that they and nothing else lights up or does anything... i

 

Double post. Please delete.

 

I think I've got it fixed!

Seems to be one of the two things I did resolved the issue. First I fully removed the bolt from my wuick disconnect I use for the ground of my battery, and theroly cleaned all the contacting surfaces, then re-applied dielectric grease. I found that with many disconnects and reconnects each winter, it seems it was asking leaving little raised marks on the contact surface, in the little Valles beside the raised areas some corrosion had formed. I put the bolt in a drill press and used a file to clean and flatten the underside of the head where it makes contact.

Next, I replaced my starter. The old one was about 20 years old. It was a high end power master mini unit, but it's seen winter driving and outdoor storage from years ago... I replaced it with the cheapest current power master mini starter that could handle 10:1 compression, since I'm building up a new wngine this winter. I found significant rust and oxidation on the block where the starter mounts. The instructions specifically say that area must be clean and barebecause the bolts are not enough to properly ground the starter to the block. When I reinstalled the new starter, I also put I bit of dielectric grease on the mounting surface before torquing and re torquing, to hopefully protect against future rust. I do admit this starter is noticeably weaker than the older higher end one that was having issues...

Pics to follow...

 

Did you ever replace the melted C145 Connector?

If not, I can build you some Pigtails for both sides of the Connector.

I even have an Upgraded version of that Connector that handles 55 Amps per Terminal instead of the Original 46 Amps per Terminal.

 

Starter as removed. Some oil residue layer on aluminum mount.

Clearly significant rust on engine block mounting surface.

Mounting surface after cleaning up with wire cup wheel on a drill.