Bobrum

I have a 1991 ZR1 5.7 L six speed manual trans. 19,000 miles.

I have a intermittent problem, when attempting to start the starter does not attempt to turn.

The battery is fully charged, push start (popping the clutch)works.

The couple times it happened it was after it was driven. Engine off an hour or more.

It just happened Sunday, after push start when I was home I turned the motor off and it started fine. Tried several times during the day, each time started fine.

What might need replacing when it is seldom that the problem occurs?

Maybe a neutral safety switch? Chip in key not working with security system?

Crabs

Common problem on the early ZR1's.
Can be fixed quickly and cheaply and isn't all that difficult to do at home:
https://www.corvetteforum.com/forums...made-easy.html

Now, before you get started cutting wires and soldering in relays, make SURE to check all the "Usual Suspects" first.
There's a ton of information on Marc Haibec's website:
http://zr1specialist.com/HAT%20Web/a...%20Probems.pdf
And at the ZR1 Net Registry:
http://www.zr1netregistry.com/Inform...art-issue.aspx
And Cliff has a superb write up here, under Starter in the Electrical Section:
http://www.zr1.net/forum/showthread.php?p=148375

Check EVERYTHING at least twice.
If you still have the DNS (Dreaded No Start), then do the mod.
I haven't had a DNS issue since I did the mod nearly 10 years ago.

'Crabs

jss06c6

I have a '91 ZR-1 with 38,000 miles. Probably not driven enough to keep all the switches good, but trying to do a little better there

Mine exhibits the same problem on occasion. Turn the key and nothing, no bendix sound, nothing at all. Ran in circles for a while and then decided to see if it was the security system. Found mine to be the momentary switch on the drivers door to identify when the door is open. I exercised it manually a few times and the car fired right up, no issues. Has happened once more, after the car sat without starting it for about two months. Same fix, fired right up. Now I'm driving it more frequently and no issues. Good luck and let us know what you find.

Z51JEFF

After bypassing the clutch switch thinking this was the issue,not wanting to start cutting wires I finally reliesed I had no choice but to splice into the starter wire with the relay mod. I've also put in a secondary ground wire at the main starter relay. As far as 90-92s I don't think there is any choice but to put in the secondary starter relay.

combatdoc

Mine does this every once in a while, what I do is this; turn the key back and fourth 5 or 6 times from the off to the start position with clutch pushed in and poof it will fire up, first time it happened I was pissed felt like I should light the car on fire or something, tested the clutch switch it was good so I figured it was the alarm but I pop started it so I scratched that out and I was never really interested in pulling plenum to check starter until it was time for porting and new injectors. I heard of the mod but I have yet to investigate, thanks for the link BTW.

jaymitchell01

What he said...

We nailed this down back in 2003, and first posted about it about 2 years later when it was safe to say the fix works. Crabs posted a schematic back then that illustrates perfectly how to wire it up in no time.

I also got into a debate with Hib Halverson over this issue. He thought we weren't troubleshooting and fixing properly, see below for your reading pleasure. After 10 years and no other viable solution found, I'd say this fix is a good one, and that the "experts" are not always experts.

https://www.corvetteforum.com/forums...post1559785966

IMHO, before you start digging in and replacing anything, just check the voltage at the purple wire with the key turned over. If you get voltage (albeit low), then all the components of your ignition system are working properly, and the issue is a mysterious voltage draw somewhere (in the wires I assume). If after the relay you get good voltage in the purple wire but no start, then look at your starter as the issue.

Just my $.02, and very cool to see the work we've done in the past is still helpful today.

JRM

Redline7g

I also have a 91 that would do the same thing. usually at the most embarrassing moment. Found a thread on here that shows how to run the relay under the hood rather than digging around under the dash. Been 2 years with no problems. Wish I had done it sooner.

RICHARD TILL

Have had the same problem 3 times in the past 17 years. First time i replaced the starter. The second and third time i fixed it by cleaning and replacing the contacts in the solenoid.

Bobrum

Well I decided to do the mod first. My mistake! I installed the relay yesterday, drove the vett for 20 minutes shut it off for a hour, would not start. Tried a couple hours later, started fine.
I am not sure what may need replaced now.

Bob

Dynomite

No mistake at all......the Relay I have added to ALL my ZR-1s (1990 and 1991)

I have done both the Relay and the Starter Solenoid reconditioning on my 1990s and 1991.........and make sure your battery is fully charged. The voltage/current to move the starter Solenoid varies with starter temperature.

Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks

The Starter Solenoid is shown in the left photo with slight burnt contacts in right photo.


The Solenoid contacts in left photo were wire brushed clean in right photo.
Also use a bit of emery cloth on the two fixed contacts.

lfalzarano

Had the same problem, until I replaced the corroded terminal block under the battery. Clean all the connectors before installing the new block.