ok so i have a 1991 z28

Up until recently, the car has been running fine

Went to get gas one morning then i could not start car after fill up
had to wait about 20 minutes then magically started

i charged the battery then it ran fine for about a week

now I am back to same issue again

things that have been done:

1) battery taken out and tested- came back fine
2) Starter tested with probe.... power to pole... when car has the issues, put probe on the one wire on the single pole, no light when turning key
3) Fuel Pump Relay replaced
4) Ignition switch replaced

So something is not allowing power to get to starter from ignition


After each replacement car would have 0 issues for about a week and then comes back. Car ran fine in the morning, sat for about 7 hours in the parking lot and when tried to start, nothing, not even an attempt to turn over.... so i wait about 10-15mins, try to start couple of times. FINALLY decides to turn over...

what could be causing this????? At this point i am not sure what else to replace but the starter... could the chip on the key have anything to do with it?....... I need to find a permanent solution as Im tired of being stranded!!

 

If your car is equipped with the VAT system in the key that could be your problem. Go to the tech aricles on this site and read up on the VAT system problems and what needs to be done.

 

IF ... you don't think it's a VATS issue ...

1st - test starter - get a nice guage wire, hold to pos side battery, and touch the small connector on the starter (one with the purple wire on it) - if the starter starts every time you do this for like 10 times, then the starter is good (you can do this with key off and the car won't start, just the starter will turn).

If starter tests fine, try replacing the starter enable relay - it's under $10 at NAPA, they should have it in stock - it's located under the driver side kick panel, maybe under the black goo that covers the hole where the hood release latch runs. It's the next easiest cheapest thing.

If still have problems, take the top off the center console, and check the neutral safety switch. If it;s an auto, make sure the little plastic tab on the switch doesn't pop out of the shift lever when changing from drive to park, etc. Mine did this and drove me crazy - I bent the bracket with some big pliers so that it wouldn't pop out anymore (can't tell ya how the manual car NSS works).

If the NSS looks like it's operating fine, it might be bad - you can test it by checking for 12v - there is a big green wire going in from starter enable relay - this shouldn have 12v when key is turned to start - the NSS when in neutral or park should allow that 12v to go out on the purple wire to the starter. A new NSS (at least for an auto) is about $30.

OK - there's a start.

 

well the car does start so the starter does work .... i like the idea of a VATS issue as I totally forgot this was a problem... I will take into consideration your other ideas though and lets see what i come up with.... it might take some time cus this always doesnt happen

 

ok, car issue reappeared today for testing....

tested the VATS bypass trick... still no start... SECURITY light stays on, does not blink......

It appears the bypass setup was causing more of a problem than not... once removed the car was able to start
readded to the system and security light back on, im assuming it is reading the ohm's x 2 (key + bypass setup)

so im back to scratching my head.... do i have a somewhat faulty vats setup where sometimes it may or may not work... bah!

 

Ok so I have been reading:
https://www.thirdgen.org/forums/elec...t-factory.html

so I have been testing the 2 white wires for ohm readings. These wire appear to come from the lock cylinder.... Sometimes i get the ohm reading correct that was on the key and other times are really low numbers. So if I am understanding correctly, the lock cylinder might be the issue??

The SECURITY light stays on and also from what I am reading, if the wrong ohm is read, it locks the start for 4-5 mins until it resets?

Why cant i just put the vats bypass resistor rig on the other 2 wires (the ones these 2 white wires were attached to) so the correct ohm range is sent to the VATS system? it appears that doesnt work either.....

 

ok i connected the vats bypass this morning and car starts with no issues now... security light goes off...

i will see if this now totally fixes the issue

 

ok i am now back to this issue, 2 years later... sigh.... car wouldnt start at all....

i pulled the resistors out tested everything and seemed ok... reconnected everything and sure enough, it starts, HOWEVER it now will not stay running! car only runs if i give gas.....

i disconnected the IAC plug obviously with same results... could this actually be a freak of nature that IAC took a crap ?