No crank condition - need suggestions

[KFoster]

I haven't found this issue, but I bet someone has covered it. 1990 ZR1 will not crank at times. Did it a few times this summer and I thought it was temp related as it cranked fine cold, but then it would not engage starter. No cranking, but all electrics worked fine. Leave it to cool over and it would fire right up. Now, it does it cold. Leave it alone for a few hours and it will crank right up. Maybe a sticking relay? Clutch switch? Any ideas? In my experience, relays won't just unstick. You can tap on them and get them to work, but in this case I did not do that. Did nothing more than leave it alone and try it later. Now I'm afraid to turn it off anywhere but home. Help.

[RussMcB]

I think the first step would be to prepare for bypassing a lot of things the next time it happens, so you can send 12v directly to the starter from the battery. That will tell you if it is starter-related or not.

To prepare, you need to locate the "purple wire" that goes from the ECU (correction - UNDER the ECU) to the starter. Make some kind of jumper connection so you can connect 12v to that wire. You will, of course, need to make sure the car is out of gear.

If the starter works with your jumper wire, then you can start debugging the other possibilities, such as VATS, clutch switch, etc. If the jumper doesn't solve the problem then you'll need to remove the plenum and troubleshoot in the starter area.

If you do a search for Purple Wire in this forum you will get plenty of details and pictures.

Oh, and park on hills. :-)

Off topic: Can we see a pic of your Pantera?

[KFoster]

Hopefully this will show up.

[RussMcB]

Nice! I like how you two dressed to match the car. :-)

[We Gone]

http://www.zr1.net/forum/showthread.php?t=21388

Check the sticky at the top of the page lots of great info.

http://www.zr1.net/forum/showthread.php?t=16778

[RICHARD TILL]

The contacts in the solenoid would also be a likely suspect. Fixed mine twice with the same problem. Cheap fix. I`m about 75 miles east of you. Shout if you need any help.

[KFoster]

Richard, I appreciate it. I didn't think about the solenoid. Never had one act like that, but could be. I will try to bypass the clutch switch when it does it again and then check the solenoid. Good ideas from everyone.

[Dynomite]

Exactly as Richard, Steve, and Russ suggest.....but messing with the Starter requires a bit of surgery requiring you put the car to sleep (that is my euphemism for removing some coolant) which is required unless......unless....you block TB Coolant :D

Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-3.html#post1581564085)

Electrical Ground Connections and Installing Starter Relay (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-3.html#post1581564089)

See this link for TB Coolant Blocking drilling and threading details Injector Housing TB Coolant Blocking (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-10.html#post1588695506)

I have blocked TB Coolant in an LT5 without removing the Injector Housings (recommend removing the two Injector Housing Coolant Manifolds however).

[Paul Workman]

Richard, I appreciate it. I didn't think about the solenoid. Never had one act like that, but could be. I will try to bypass the clutch switch when it does it again and then check the solenoid. Good ideas from everyone.

Marc Haibeck presented these procedures at the Bowling Green spring gathering, one or a couple years ago. This and much more info is also on his site. For you reading pleasure... (http://zr1specialist.com/HAT%20Web/articles/Diagnosing%20Starter%20Probems.pdf)

:cheers:

[Z51JEFF]

THE PURPLE STARTER WIRE DOES NOT COME FROM THE ECM. The wire runs UNDER the ECM. Misinformation will only add to the confusion here folks.

[Z51JEFF]

This is a thread I wrote on the starter relay mod from the other forum,not sure how long it will stay here but I gave it a shot. http://www.corvetteforum.com/forums/c4-zr-1-discussion/3682271-secondary-starter-relay-modification-made-easy.html

[KFoster]

Cool weather is here now. Haven't had the issue come up again. Located the wire to jump it. Battery was low, once charged it fired right up. When the prob started it seemed to happen after running a while in really hot weather. Might not show up again until then. If I figure it out, I will post what I find. Might be a good idea for the switch bypass anyway. I'd rather have it if it works, but I don't know if it's worth the gamble since so many see it as an issue.

[Dynomite]

Add the Relay and recondition the starter.....I do it to ALL ZR-1s....I also Block TB Coolant at the Injector Housings and add Differential Drain on ALL ZR-1s :cheers:

Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-3.html#post1581564085)

Tech Info - LT5 Added Systems (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-11.html#post1590759160)


I do those modifications no matter the mileage and no matter if they are not in immediate need of the modifications :p

[Racinfan83]

Cool weather is here now. Haven't had the issue come up again. Located the wire to jump it. Battery was low, once charged it fired right up. When the prob started it seemed to happen after running a while in really hot weather. Might not show up again until then. If I figure it out, I will post what I find. Might be a good idea for the switch bypass anyway. I'd rather have it if it works, but I don't know if it's worth the gamble since so many see it as an issue.

I had a no start ONCE. And once was enough. Embarrassing to say the least, and had I not had a bunch of club members there willing to push the car (It started right up when I popped clutch) it would have been an expensive tow bill.
I did Dyno's relay shortly thereafter, and also put in a new battery. Never had an issue since. The good thing about the relay system is that if it "no starts" again - I know I have to excavate the starter and clean the contacts. Takes a lot of the guesswork out of the diagnosis..;)

[WydGlydJim]

Basically if you can hear a clunk at the starter, but no crank, it is a starter issue...no clunk probably one of the other switch failures......

I had a no start condition after winning best in show engine....kinda funny..
:D

[Dynomite]

Basically if you can hear a clunk at the starter, but no crank, it is a starter issue...no clunk probably one of the other switch failures......

I had a no start condition after winning best in show engine....kinda funny..
:D
A NO Clunk could be a stuck Solenoid.

That was Best in Show. Not Best in Run. ;)

[RussMcB]

I had a no start condition after winning best in show engine....kinda funny..
:DThat's funny. The first thing I pictured (which I'm sure isn't true) is that you had spent all day pressure washing the engine to get it looking perfect. :-)

[KFoster]

Warm weather is back and so is my issue. Happened a couple of times. My Uncle has as C3 and the guy helping him with it has worked on a ton of C4s and said my problem sounds like VATS. He said a lot of times you can wipe the key off and try again after 30 seconds and it will work. Haven't tried that, but really sounds like it might be my issue. Ordered the bypass from Ecklers and I will see if that works. IF not, I will add the bypass relay for the clutch switch. Will see how it goes and update accordingly.