I have read several threads on the forum as well as some other Internet sites regarding the VATS.

I don't yet have a complete handle on my issue.

1986 Vette with Manual Trans

1) The engine always cranks with the key
2) Most of the time it starts right up
3) When the failure occurs the engine cranks and sputters but won't start no matter how many tries.
4) After a failure like 3), if you let it sit a while the next try it may start right up (but sometimes you have to wait again for a while and try again).
5) I can hear the fuel pump come on with all starting tries.
6) It seems to not be getting fuel.

I think the signal is failing to get to the fuel injectors to pulse.

Is this likely the VATS Module failing to send the signal to the ECM that I have the correct key? Some threads here suggest that if its not reading the key correctly it wouldn't even crank.

I need help with this one? Any other ideas?

Thanks

 

I had this exact same prob for about 3 months for messing with my vats and about 4 hours of wireing,do yourself a favor and go on ecklers and by the bypass plug,it only costs 25$ and everything is back to normal,oh u will need to fond out the ohms on the key with a tester and look up what key # it is on google! If u have anymore ?'s pm me and i'll be glad to help!

 

If it cranks, it's not VATS
Does is start easier if the gas pedal is fully depressed during cranking ??
Have you tested for spark and fuel pressure during your no starts ??
Here's a little help, if you don't have the GM bible.
http://members.shaw.ca/corvette86/6E3-B%20Symptoms.pdf
http://members.shaw.ca/corvette86/En...ButWontRun.pdf
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
http://members.shaw.ca/corvette86/Ig...System-EST.pdf
http://members.shaw.ca/corvette86/Co...0View%2086.pdf

 

I agree so far as it is not your key or related wiring, I think it could be possible for the VATS module to fail to allow starter operation but not fire the injectors.

But this is not a classic VATS failure, probablly best to check the basics as suggested.

 

I will check the basics and tune up. What puzzles me is it runs real nice once started, so I wasn't thinking this was a tune up issue at all. This may be one of those really hard problems to diagonose. It just seems to me that when it fails it's a fuel issue.

Thanks for the inputs..

 

Not the vats, the vats module sends a signal to the computer, which then authorizes the start relay and the injector pulse. You might check the tps (throttle position sensor) or possibly the ignition module. First thing I do is check for proper fuel pressure.

 

Hi, I am having the same problem as tdf. Seems I have the same symptoms. I have an auto trans. Even when I apply gas after cranking for a second it won't start. It definitely seems like it's not getting feul. I was wondering if tdf can chime in and tell me what he did to solve the issue. Thanks.

 

I have added a new set of MSD wires. I ordered a complete distributer tuneup kit from Summit Racing, but they sent me a 4 pin ignition module in lieu of the 7 bin module my 86 requires. So, I'm in the process of returning that set and buying MSD or Excel or ??. Does anyone have a recommendation for coil and ignition module sources??

I still have the problem!

 

just get ACDelco parts, MSD 8/8.5 wires and Rapidfire plugs, and you should be great to go...

 

When it won't start, that is when you should do some testing to find out why it won't start. Engines need spark and spark at the right time, fuel and air and in the correct ratio in order to start and run. First use your timing light for spark and timing. Also, pull a plug wire and see if the spark is at least 1/2 " long. Next, measure the fuel pressure and see how long the pressure holds up with ign off. If it drops rapidly, then you may have leaky injectors which allow too rich condition to start and run. Next, use a noid light or a low power 12v lamp like a side marker lamp connected to an injector socket while cranking to see if it flashes.

 

Today I installed a new ignition module and checked fuel pressure. 41 psi after the pump runs and before starting. 38 psi while running. Once today it still behaved strange on startup, like it wanted to go but was lacking something. Once it got spun up to normal idle speed it ran fine.

I'll stary on top of this issue till I find the problem. Not a lot of time as I'm installing a new engine in my daughters car the past few days.

 

The new ignition module has made a difference, it has been starting, but I don't want to declare victory quite yet.

 

www.vatssucks.com


IF your issues is VATS related, it is most likely the computer module portion that went bad. You will have to have that programmed out.

I bypassed my lock cyl, and my starter enable relay... yet a month later it was doing exactly what you described. I had a new chip burned for my car and had the remaining VATS stuff programmed out and as soon as I put that chip in, I've NEVER had that problem again.


....but thats assuming that is YOUR problem.... starting issues with fuel are hard to diagnose sometimes.

 

Reading (and comprehension) are fundemental!!!!!!!!! He posted that his engine cranks every time, so VATS is working. Bypassing VATS sets you up for an easy steal! 99% of thefts are done by bashing your column and jumping the ignition. Your insurance company will not pay you the replacement value of your stolen vette, or any other car! Keep your car in good repair.

 

Good think I can read then...

He stated:
1) The engine always cranks with the key
2) Most of the time it starts right up
3) When the failure occurs the engine cranks and sputters but won't start no matter how many tries.
4) After a failure like 3), if you let it sit a while the next try it may start right up (but sometimes you have to wait again for a while and try again).
5) I can hear the fuel pump come on with all starting tries.
6) It seems to not be getting fuel.

This is exactly what mine did. It started most of the time, but other times it would do EXACTLY what he just stated. Mine turned out to be VATS related and nothing to do with my ignition system.

This CAN be related to both the starter enable relay OR the computer issue. I managed to have both fail in my car.

The ONLY thing I did to fix mine was completely remove VATS... I have NEVER had an issues since then. MY problem was 100% VATS related.

SO.... what I offered by reading my site was a 100% legitimate fix IF that was his issue. You can choose to replace all the failing parts or remove it altogether.

Also, on my VATS site, there are plenty of part numbers and instructions on replacing your broken VATS components too. It's not completely about removing it. You are right... Reading IS fundamental.

 

Hello...

Where is VATS located???.

Here is my problem... Any other ideas than listed in this threat.

My 1989 C4 won't starts, I give you all the info...
When I came in to my car the "security" light binks.
I put the key and turn on, and "security" light come off.
I try to start the car and the engine moves buts there no explosions, and never start.
When I'm trying to start (while engine is moving) I can see "security" light and "key lock" light on.
I try to bypass VATS using 1130 ohms resistance.
I try to bypass VATS using my own 5v 30hz signal generator (I don't know if I make a goog generator becouse I dont have osciloscope).
Always imposible to start.
I put a little amount of GAS in the air intake Tune Injection Port and the engine runs perfectly, but when the GAS is over, the engine come down and gets off.
¿What more I need to check?
¿Where is VATS located in my car?
¿How can I check Gas pump, injectors, ECM, etc...?
I check code problems using the diagnostic connector and show all right (12, 12, 12, 12, 12, 12).
When I turn off the key and get out "security" light become blinking.
I'm getting crazy , here in Spain there are few garages to fix this kind of car and too expensives.

Help me and find a way to run my corvy.......

Thanks in advance for your time and best regards from Spain.

¡¡¡Sorry my bad English!!!

 

With the help of several here, we quickly determined this was NOT a VATS issue.

As suggested I went back to basics and:

1) Checked fuel pressure. It was right on spec. 41 psi cranking and 38 psi running.
2) Replaced ignition wires and cap and rotor. Still had the intermittent no-start issue.
3) Ordered a new ignition module and coil. Installed the ignition module.
BINGO!!

It now starts every time! I would not have guessed that these symptoms point to the ignition module. However, at least one other person had this same symptom and a new ignition module was the cure for both of us.

Why it would start after setting another 5 minutes will remain a mystery for me anyway.

Thanks to all that chimed in!