Z won't crank

[s8epilot]

Hello all,

So I must have messed something up over the weekend. I am going to start by giving some details on my car and then explain what I did. 1993 300ZX NA 203K miles. Have owned it 26 years. I'm not a mechanic but I have done a few projects on it (replaced starter, replaced a fuel injector, replaced coil overs). My car generally runs fine but has a handful of annoying issues that I have occasionally tinkered with to try to improve. I will say that every once in a while when I go to turn the car on it won't crank. This happens about once a month. The lights on the dash light up but the starter doesn't turn. Typically if I try again it will start normally. I had to get the ignition replaced about a year ago because a key broke off in the ignition. This issue where occasionally it won't start happened before and after getting the ignition replaced.

An annoying thing is that frequently my clutch pedal "clicks" or squeaks. It has done this for at least 15 years. This issue comes and goes. Sometimes it won't do it at all, but usually it clicks. Sometimes it will do this when depressing the clutch and sometimes it will do it when releasing the clutch. And sometimes both. I have researched this and over the weekend I tried to rectify this issue, which sadly I don't think I did and in the process I think I broke something. I read some people fixed this by spraying WD40 on the rod that goes through the firewall, or on the spring. And some people fiddle with the spring. My theory is the spring is the culprit on the clicking and the squeak is the rod that goes through the firewall.

So over the weekend I moved the seat back, jacked the car up and put it on jack stands on the front to get it a little higher to make it easier to access under the dash and I removed the under the dash panel and that vent tunnel so that I could see the pedals more. I sprayed a bunch of WD40 on the rod that goes through the firewall and on the place where the spring connects to the pedal and the pivot of the pedal. I also turned the cotter pin on the spring a bit. Just moving the clutch this doesn't seem to have helped much. So that is a bummer of course. This process took me probably an hour or so. After working on this for at least an hour I dropped the car back down and had the thought to take it for a drive. I had the windows rolled down and went to pull the hatch lever open the hatch and then the alarm went off. I must have pushed the door locks while I was wiggling around under the dash and not realized it. I of course have done this sort of thing before so I just locked and unlocked it with a key. Then I took the tops off (the reason I was opening the hatch) and got in the car. When I went to put the seat back forward I noticed the motor was super sluggish. I didn't disable the door switch so while I was working under the dash I had a door open and the interior lights were on. Sure enough, it wouldn't start.

I put my jump pack on the car and after about 5 or 10 minutes of the jump pack charging and still on the car and a few tries I got it to start. At the time I figured I had drained the battery. I drove/idled the car for about 15 minutes and then got to a place to park it kind of on an incline, and shut it off. When I went to start it again it wouldn't. I did part it on an incline so I just put it in neutral and let it get some speed then bump started it. After this I drove it for another 10/15 minutes and took it back home.

Now I can't get it to start at all. I had the thought maybe this was the last straw for the battery (it was 5 years old) so I replaced that. No luck. I checked all the 10 amp fuses under the dash. All look OK. I'll check the others next. Any other ideas on what I should do next? I'm thiking maybe it is that switch that makes sure you have the clutch depressed.


Ryan

[VStar650CL]

Jump the Brown wire at the clutch switch to ground and see if the engine will crank. If so, you have a bad clutch switch. If not, you most likely have a bad starter relay.

[s8epilot]

Thanks VStar650CL, I have looked at the relays, which one is the starter relay? Is it the one labelled "ign coil"?

[itsa300zx]

Have you looked at the rubber/plastic stopper pads that push against the clutch switch? Located on the clutch pedal arm.
They often fall apart after 30+ years.


Starter relay is located inside the drivers side wheel well liner, behind the wheel, typically blue.

[s8epilot]

Thank you for that information on the starter relay. I have tried to confirm the problem isn't the rubber part by pushing the button closed with my hand and attempting to start the car. Car in Neutral of course.

Thanks!

Ryan

[VStar650CL]

Thank you for that information on the starter relay. I have tried to confirm the problem isn't the rubber part by pushing the button closed with my hand and attempting to start the car. Car in Neutral of course.

The switch is a very simple setup that works by grounding the starter relay coil when the pedal is pressed. Jumper ground to the Brown wire, if that lets it spin then the switch is probably bad. To make sure it isn't a bad ground wire, then jump Brown to Black at the connector. If that lets it spin then the wiring is fine and the switch is shot.

[s8epilot]

I did some diagnostics on the clutch switch last night and I think it is working OK. I confirmed it is connected to ground. I also tried shorting it out. Same behavior, starter doesn't engage.

I think my next step is to check the starter relay. I have searched for how to access it, looking for videos and also I looked at the service manual. I know it is in the driver side wheel well, but would like to read up on accessing it to ensure I don't break anything off trying to get to it.

Thanks!

Ryan

[itsa300zx]

Here is a short guide, remove the rear section of the wheel well liner. I just crank the wheel full right so I don't need to remove the wheel. Couple screws and clips

http://www.twinturbo.net/ttnettech/star ... relay.html

[s8epilot]

Thank you very much for that info!

Ryan

[s8epilot]

Today I pulled the starter relay out. I confirmed the relay works by manually energizing it and confirmed that the contacts close when it energizes. I then confirmed that when I start the car the relay fires. When i had the wheel well open I could clearly hear it.

Thoughts on what I should check next? Get under the car and check the starter directly?

Thanks!

Ryan

[VStar650CL]

Yep. See if the juice coming out of the relay is reaching the solenoid terminal on the starter. If it is, try giving the starter a whack with a deadblow hammer while an assistant turns the key. If it spins, you have either bad brushes in the starter or a bad contactor ring in the solenoid.

[s8epilot]

"try giving the starter a whack with a deadblow hammer while an assistant turns the key."

Yesterday after troubleshooting the relay my kid was coming home from college for fall break and I needed to move my car to re arrange the garage so his car would fit I had my neighbor help me push it out of the garage and then my driveway is steep enough that I can let it roll down and bump start it. So I did that, I drove it around the neighborhood a bit, went to the grocery store (let it run while I went inside), and then drove it back and put it back in the now rearanged garage. My next plan was to get it up on jack stands and test out the procedure described here. But tonight I had the thought that i should just try to start it, and sure enough, it started right up. I shut it down, then started it again. Is me driving it around the equivalent of hitting it with a rubber hammer? If so, then at least I have found that the culprit is a starter going out and that is an easy enough fix.

Thanks!

Ryan

[itsa300zx]

There is also a 10gauge white cable that runs from batt positive down to the fusible link then to starter solenoid.
Make sure that wire is tightly secured.

[VStar650CL]

Yep, @itsa300zx is right, make sure that solenoid wire and the main battery cable are both secure. If they are, then yes, the vibration from driving around is probably equivalent to a hammer whack, meaning your starter brushes or solenoid contactor are bad.