79Rod

1987 Corvette L98
Ok, heres the problem: when I turn the key the engine wont cranks. I jumped the starter enable relay (yellow and green wires) and the engine cranks, but just start for 3seconds aprox. then dies.
then I have to wait 1 min aprox to do the same. If I dont want to wait that minute the engine just crank but dont start.
Checked:
spark: ok
fuel pressure: ok
No SES codes
16.3 ohms all injectors

I measure the key pellet resistence: it measure the same on the key and on the plug that its located running down the steering column. so I think it cant be the key cylinder.

what could it be?? I think its a VATS problem. Can anyone post a wiring diagram please??

1986coupe

Did you try your spare key?

C409

....... Do the diagnostic check on the Ignition control module ... or have it tested ...... ( most national auto parts chains will do this free ) ... or replace it ...... That should solve the running problem ... the no-start is VATS .............

jfb

Your symptoms are of a defective connection of the ignition lock with the key pellet. VATS won't allow a crank, nor will it allow the injectors to pulse if the VATS module measures the pellet resistance more than 4% from its assigned value. If you do measure the resistance less than 4% from the assigned value and the start enable relay won't close, then you might have either a defective start enable relay or a a defect in the ECM. If the relay is bad you can jump the start enable relay and the car will start and run. That your engine won't continue to run makes me believe that the problem is in the ign lock. A new lock has new contacts that make connection to the pellet. Also, if it is the ign lock you can connect a resistor the same value as the pellet across the two wires in the wiring harness going to the VATS module and your car will crank, start and continue to run.

79Rod

I jumped the starter enable relay and the engine cranks...but run just for about 3seconds...then dies.
Another test I did was: I grounded the starter enable relay direct from battery ground--> the engine cranks and dies after 3seconds. This test told me that the problem is not the starter enable relay, is the ground source for the starter enable relay. My question is: what gives ground to the starter enable relay???
I think something is cutting off fuel (injection pulse)...because I have spark and fuel pressure.
thank you guys for your post....

87 vette 81 big girl

I will bet you $2.00 also like I did with Sammy,
Calderone.................

Scroll down & you will see he has similar starting issues on his 1987 C4 Coupe too.

BROKEN PASSKEY Lock cylinder wires.

NO One believes this ex GM Master Mechanic.

LOL

I have PayPal.

Both You & Sammy deposit your $2.00 each when You find out I am right.

LOL

pmihaltian

Had a similar problem a few years back. Turned out to be a defective ignition lock on the steering column (worn out). Changed it out and it has worked fine 100% of the time ever since.

3D87C4

There may be a delay before VATS cuts off the injectors. You are getting it to crank by bypassing the start enable relay but it sounds like VATS is still cutting off the fuel.

I have a flaky Start Enable Relay, or a short on circuit 965. When I intentionally trigger VATS either by taping the key or disconnecting the wires under the dash my car will crank, catch for a second, but not run.

I explored this in rediculous detail here:

http://forums.corvetteforum.com/c4-t...-question.html

It sounds like you have a VATS problem. Brian may be correct as to why.

djoksch

I used a dental hook, reached into the key cylinder and bent the pellet contacts out (very carefully). Next, I cleaned the contacts for all door switches. The ECM needs its VATs ok signal to start (starter, injectors for a start). This worked fine for about a year, and after my wife was stranded, I disabled it.

AGENT 86

http://members.shaw.ca/dankai/Vats%20Electrical.pdf

Sammy has a problem with VATS module not supplying ground to enable relay.
His VATS module is supplying the signal to ECM to allow injector pulse.
His VATS module seems to be very happy with the lock cylinder wires and the input they send.

You owe me $2

79Rod

thank you agent86 for the diagrams.
I also have to mention that once I had a code 46

79Rod

yesterday I connected the Bakers electronix bypass.
Guess what..... the engine dont start..
I bought the dual frequency..tried both signals and nothing happens.

also I measured continuity from ECM to all injectors: continuity OK

3D87C4

Same symptoms as your orriginal post?

79Rod

problem solved.....(I forgot to connect the fuel pump fuse)
that baker electronix VATS bypass do the trick.
awesome!!!
thank for your posts guys.

silversurfer57

Need some help here, bought an 87 vette, need another ignition key made with chip , only have vin number , is this enough?

Rod Schneider

Take the key to any Chevy dealer. They have a tool that reads the key and they can cut you a correct one.

silversurfer57

When decelerating on my 87 vette, it sounds like a gurgling almost struggling noise? Muffler? need some help here.