87 starting problem...need Help!!
Thread Starter
Intermediate
Joined: Aug 2008
Posts: 48
Likes: 1
87 starting problem...need Help!!
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??
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??
Le Mans Master
Joined: Feb 2005
Posts: 6,475
Likes: 564
From: Clearwater Florida
....... 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 .............
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
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.
Thread Starter
Intermediate
Joined: Aug 2008
Posts: 48
Likes: 1
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.
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....
Melting Slicks
Joined: Nov 2008
Posts: 2,765
Likes: 5
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....
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....
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
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
Your symptoms are of a defective connection of the ignition lock with the key pellet. 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.
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.
Melting Slicks
Joined: Feb 2011
Posts: 2,322
Likes: 6
From: Los Altos CA
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....
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....
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.
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Intermediate
Joined: May 2008
Posts: 38
Likes: 1
From: Yuba City CA
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.
Team Owner
Joined: Jan 2003
Posts: 20,277
Likes: 236
From: Summerland B.C. Canada
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
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
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
Thread Starter
Intermediate
Joined: Aug 2008
Posts: 48
Likes: 1
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
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
Instructor
Joined: Dec 2012
Posts: 105
Likes: 15
From: Ball Ground Georgia
