petecaballero

Here is the history, I have a highly optioned 1986 with a 4+3 and 80K miles that since I bought it would occasionally not start. While I never confirmed it, I assumed it was the VAT system because after waiting a few minutes it would start with no issues. The car has sat in a garage for the better of 8 years with an occasional start here and there. I decided to pull her out of hibernation and get to work on her. Check / replaced fluids and she started right up but showed the results of being parked for such a long time.

After she started a few times, once day she didn't want to start. I assumed it was the VAT and left it. Tried several times given the computer time to reset and nothing. Then I noticed I couldn't hear the fuel pump so I replaced the fuel pump and she started right up. The brakes had no visible fluid in reservoir so I added new fluid and tried to bleed. Fluid doesn't get to the rear brakes so couldn't bleed the rear. Different issue so I will leave it at that for now. Back to getting the car started. Now, the car doesn't want to start again and I can't hear the pump. I noticed that my security light isn't coming on at all. The car is jacked up in the front so I can get under it to check for loose wiring but can't find anything. Now the car doesn't want to come out of gear. The clutch feels a little soft but still has fluid.

So, not sure if it is the VAT system, starter, starter solenoid, faulty clutch or clutch switch. Any ideas where to start? I hate to just replace parts without confirming they are bad. I have a good mind to just bypass the VATS because I am pretty confident that at a minimum that is bad because it would do it since I bought the car in '92. There maybe other things wrong but surely the VAT is contributing.

Not sure which VAT something to order. Anyone have an 86 that successfully bypassed the VAT? If so, which one did you get specifically? Any other ideas or guidance anyone has with a similar experience? Thanks all for any advice, I am going a bit crazy here with all these electronics.

antfarmer2

you have to test your key to get the right one look on youtube to see how with a meter then ebay has cheap kits or just cut a new key. mine was hit and miss new key for me.

Cliff Harris

When it doesn't start, does it crank? If it cranks then VATS is not your problem.

The SECURITY light has NOTHING to do with VATS. It is controlled by the TDS (Theft Deterrent System), which is not connected to VATS in any way. It's only function is to honk the horn if a door is opened while the TDS is armed.

Also, the ECM will hold error code 46 if it disables the injectors because of VATS. Have you pulled error codes from the ECM?

MavsAK

I can't hear the pump with the vette either. Never could, not even with my 255lph fuel pump. But it starts right up.

Is it turning the engine over when you turn the key? Or does it just sit? If it just sits, it's either your starter or the solenoid. Vats gets blamed way too much for starting issues. 99% of the time it's your 20+ year old starter to blame.

If it's turning the engine over good and strong, (not slow and weak, actually quick a SLOW and worn out starter will give you fits too) then it's either Fuel Or Spark.

At that point you have two things to check. The first is the presence of fuel. Get a fuel pressure tester, and test your fuel pressure. If it's less than 36 psi (on a TPI car) An LT1 (92+) I think it's 38 psi as minimum, it's not going to start. It should be between 36 to 46 psi. No pressure? It's either the fuel pump, or pressure regulator.

Next thing to check is your spark. I would recommend testing your ignition coil, wires, and your ignition control module.

Don't assume everything is good just because it starts occasionally. Parts can have intermittent failures, or rather intermittent success.

Cliff Harris

After the initial 2 seconds at ignition-on to prime the fuel rails for starting the fuel pump does not run unless the engine is turning.

petecaballero

Thanks, I will look into this.

No, it doesn't crank. Other times it cranks and starts perfectly but lately seems to not want to crank at all anymore. Maybe a sign that the starter is finally shot? Haven't pulled codes because I was confident it is the VAT or starter. Now I am not so confident anymore. Might due a VAT bypass and a starter replacement just to be done with those two possibilities. Just wish there was a definite way of troubleshooting to determine the real culprit. Thanks.

No, the engine is not spinning now at all. I will check the fuel system and you have a good point, don't assume everything is okay because it starts occasionally. Thanks!

Didn't know that. Thanks.

jv9999

You could have a bad starter inhibit relay (behind the information panel). Drove me crazy on my '87 for a while.

Cliff Harris

When you turn the key to the start position you should be able to hear the starter enable relay clicking. It's located behind the DIC in the center cluster. Normally the starter makes too much noise to hear it, but if the starter doesn't crank then you should be able to hear it.

DinoBob

Whatever you do, get a factory shop manual and carefully go through the diagnostic procedures as much as possible. Otherwise you will be throwing money at problems which usually results in frustrated and disillusioned owner. After all that time sitting I would definitely start with some basics; fresh fuel, fresh filter, clean the key pellet on the key, and; take a block of wood and a hammer and tap the injectors, all of them, gently but firmly a few dozen times each. This helped my dads 86 to start and run after sitting for two years. Well, that and a fuel pump.