OK, I feel guilty telling you I found my problem. A few days ago we had a tremendous rainfall in a short time (1.6")
I went to test my fuel pressure even though I could hear the pump and it was 43 lbs. Then when I took the gauge off I noticed the gas that came out didn't feel right....it was water! I had anly a 1/4 tank of gas but I pumped out over a gallon of water. That well in the back is getting a large hole put in it to prevent this from ever happening again! Wish this could help you, but you probably already check that!
I do believe your problem is fuel related though.
Good Luck

 

I don't know where you get your info, but the 86 VATS cuts off starter enable relay and will not fire the injectors. You DON"T have a VATS issue. You can crank the motor, your Actron tester says the injectors are being fired, it runs when sprayed, why do you still believe its a VATS problem.
I give up, good luck

 

To prove the signal from the Vats decoder module on circuit 229 is getting to the ECM to allow the injectors to pulse, cut the Dark Blue wire.

(Solder it back together when you're done).

Hook up your Actron injector tester, crank the engine and see if the injector led still pulses.

 

MR Agnet:
I found this link on the web http://www.corvettecenter.com/_junkf...echhistory.htm that says that the '86 also does cut out the fuel injectors...good call...my bad.

It says:
"PASS-Key Theft-Deterrent System
Corvette pioneered the use of PASS-Key, originally known as VATS (Vehicle Anti-Theft System) on Chevrolet passenger cars. The system, introduced in 1986, relied on a pellet embedded in the ignition key. If an improper key was used, the system cut off the starter and the fuel injectors, immobilizing the Corvette. The VATS system is credited with reducing Corvette thefts by 45 percent in the first year alone. Theft-deterrent systems are common among many Chevrolet passenger cars today, including a new system called PASSLock on some Chevrolets that offers similar protection without the need for a key-mounted resistor pellet. "

 

So I found this link on the internet last night: http://fp.enter.net/~rockcrawl/passkey.html

This morning I went to radio shack to get the parts. I used this web page as templet to build my own module. My module is for the VATS II system with 5volt @ 50HZ output for the ECM B6 pin.

Below is line diagram of the module and Radio Shack Part #'s(I added the part #'s and a few extra parts).


The Parts:



Assembled and Voltage Test:



Ground PC board and fit into box



Finished Assembly:



I have no way of knowing if this thing is putting out a 50hz square wave or not (I have no "O" scope .....but the voltage level is safe.
I'll wait for the rain to stop then I'll install this thing and let you know what it does.

 

Here's a C&P that might help. Good luck:


L- 98 Engine Start Sequence



When you start an L-98 engine Corvette, a series of events take place that causes the engine to run. Knowing the sequence will help you troubleshoot no start conditions.

Fuel Rail Pressurization:

When you first turn the key to the “on” position, the fuel pump will run for 2 seconds pressurizing the fuel rails. There is a Shraeder valve on the passenger side fuel rail near the rear of the engine and if you measure the pressure there after the pump runs, you should see between 40-42 pounds of pressure. The reading will go to 38-40 pounds nominal once the engine is running.test by attaching a fuel pressure gauge to the fuel rail at the shrader valve, on TPI and LT1 engines its located on the pass side fuel rail

Initial Crank Action:

If you then rotate the key to the start position (assuming the anti-theft system has not disabled the starter), the engine will rotate.

Once the oil pressure has reached 4 PSI, the oil pressure switch will close allowing the fuel pump to run. (Note that you should have a black oil pressure switch/sender. It is mounted behind the distributor on the driver’s side and if it is not black, it is suspect due to a run of bad units that stayed in the GM parts pipeline for some time).

The distributor will send a string of pulses to the ECM (Engine Control Module) in response to the engine being rotated by the starter. These pulses continue as long as the engine turns (both starting and running) and if they are not present, the engine will not run.

ECM Reaction:

If the ECM sees oil pressure greater than 4 PSI and the reference pulses from the distributor, it will energize the injector drivers which will begin pulsing the injectors on for 4 ms (milliseconds) periods. (In the L98, all injectors on one side of the engine fire at the same time followed by all injectors on the other side firing at the same time. On the LT-1, the injectors are fired individually at the appropriate time).

The ECM will also pull in the fuel pump relay in effect paralleling it electrically with the oil pressure switch. (If the fuel pump relay fails, you can still normally get the car to start and run unless you can’t make at least 4 PSI oil pressure. This is a “limp home mode” feature put in place to allow for a fuel pump relay failure).

The ECM also monitors the TPS (Throttle Position Sensor mounted on the throttle body assembly) and wants to see .54 volts at this time. If it sees appreciably more than 0.54 volts, it will assume the engine is flooded and the driver has pressed the accelerator to the floor to clear the flooded condition and restrict the fuel flow as a result. (.54 volts during start and at idle from the TPS is very important to both starting and run performance.)

Assuming the ignition module is good (meaning there is a spark of sufficient intensity to ignite the fuel), the engine will “catch”.

 

THE GOOD: VATS Bypass module works - - 5 volt @ 50HZ achieved! The Actron 3 harness tester shows flashing LEDs when hooked up and cranking. Engine is trying to fire now intermittenly. Note: I also re-tested the harness with out the bypass installed....the LEDs were very very faint in comparison. Seems like too low of voltage to fire the injectors.

THE BAD: Hooked up timing light to the plug wires to check for spark signal. Some times there's spark other times no spark. Seems there is something wrong in the distributor now. Will dissassemble in the AM.

 

Had been wondering how you were doing. with Agent...no vats problem. Seems like you've been throwing alot of parts at it. #1, did you replace that sock like Agent suggested? looked ugly to me also. #2, I suggested you check the pickup coil there is an easy test for this. It's not the coil you replaced, the pickup coil is located in the base of the dist. unfortunately you have to pull and disasemble the dist. to replace it...but check it first. You have an ohm meter, just make sure you kinda twist the wires while checking. It all still comes back to a fuel delivery problem....you've already proven that!!!!!!!!!!!!

 

I think my problem is vats related.
I just got through trying to crank it and the starter shut off and it's acting like the battery is dead but i know it's not because i keep a battery charger-maintainer on it when not driving it and it shows it's fully charged. then something under the dash on passenger side started making this loud grinding noise like a timer grinding . it was vibrating that side of the dash pretty good. I was trying to take the dash apart to find out what
it was and it started to rain. Any Hints as how to get the lower dash and bread loaf off ? I have taken all the screws out that i could see and took the center trim of the dash but still cant find whats holding it in place.
Could it be the vats timer trying to freeze up on me? Or is it not a separate unit from vats?

 

I just went through this.
put a meter on the start wire on your starter solenoid, and put the meter on the windshield so you can see it. turn the key to start. if you have 10-12 volts, your starter is worn out. mine was. I kept thinking it was the vats the whole time, even when I was grumbling to myself and removing the starter.
My car is an 86 with 130,000 miles.
2. there is nothing over there to make a grinding noise except your heater blower motor. If the volts are low, and the motor is beginning to wear out or the bearings are shot, the motor might be grinding.
don't take off the breadloaf, look under the dash on the right side, and remove the black plastic cover forward of the knee carpet. that gets you access to the underside of the dash over there.

 

But i did not have my ac or blower turned on???
It's like a buzzing grinding sound..

 

Yellow:
Sounds like a battery problem to me. In my '89 when the battery is disconnected or the voltage is too low it turns the air conditioner on by defalt when the car is started. You should try to jump start (with another car or a jump pack) the car. If the starter works when jumped then there you go...its a battery problem.
If it cranks, run/drive the car for a while to see if the car is charging the battery. Get the battery tested is your in doubt.
If the car doesn't crank, check the starter or you can look into a myriad of VATS issue.
P.S. Don't worry about the sound under the dash right now...aint nothin' in that area but the blower fan and heater coils. To remove the "loaf of bread"(passive restraint pad) you have to take off the entire upper dash....this will suck. The main module of VATs system is behind the "loaf". Good luck!

 

Thanks engle. It was the neg.terminal corroded. I guess i need new injectors tried another test light and it's blinking brighter than the other light. engine turns over fast now but it will only try to crank for a second the first time i try it. then it just turns over really fast.

 

Yes, I changed the fuel pumps strainer(new sock = $7) when I had it out (The picture posted with the dirty strainer was taken just after it came out of the tank.)

Yes, I did the ohm test the Pick-up coil: 857 ohms this seems ok...I used this guide as a referece. http://www.autozone.com/az/cds/en_us...es.htm#hd1-1-1

Today I pulled the distributor apart, checked it, then reassembled it - everything seemed just fine except that hood seal puts a lot of pressure against the new over sized HEI coil. I also took a hack saw to it and cut the cover back to keep it from binding. Attempted to start the engine but I'm still only getting intermittent firing.

Maybe tomorrow I'll take this thing apart again and change the pick-up coil since its the only thing on the distributor that's not "brand new". More $$$$$$

 

Mallory Mod: I cut the back and the side off:

 

Last night, in the midst of my preparation of committing hari kari over my vehicles problem/problems I stumbled across this aritcle entitle "WEAK SIGNALS
It’s the Last Place You’d Look": http://www.mightyautoparts.com/pdf/articles/tt71.pdf

"DEGRADED MAGNETIC MATERIAL
The exposure of used oil at high
temperatures to the rotating pole
piece may result in a swelling and
degrading effect on the magnetic
material. This is why the ’88 Chevy
pick-up was stalling; it was due to a
weak signal. The symptoms are
pronounced, especially when the
engine is loaded at idle with the AC
on, trans in gear and power steering
pressure load on the engine. Lab
tests show that clean engine oil had
little effect on the properties of the
magnetic material."

Will replace reluctor and pic-up coil shortly!

 

Replaced reluctor shaft and pick-up coil. Note: reluctor is perm. attached to the distributor shaft. The shaft appears to be a "dealer only" item. I opted to change the entire distributor base assembly from Napa: Assembly includes base, shaft, cam gear, new ICM pack and pick-up coil RFcapacitor/coil harness.

New part had no effect on the "no start" condition.

 

I think you are gonna have to do what i have to do and bite the bullet and buy new injectors.

 

Yellow 00:
Let me know how that works out with the new injectors.

 

I've been following this thread and it seems like you've done just about everything; however, try rereading my C&P above - I've bolded some parts about the oil pressure switch and oil pressure.

You might want to try that.