Hey,hello everyone, I bought an ol 1987 C4 Corvette Coupe off of a dear friend of mine that i haven't seen in years.,the way it happened was during our conversation i had inquired about his C4 he used to drive around in,.. he said he still has it, ..said it was back in early 2020 a few months before Covid-19 hit hard,,he had drove over to the local market, but when he got back in the car... it wouldn't start, no crank, no lights...nothing...had it towed home pushed in the garage where it still remains...then.said hes never had any problems with it, always ran great...but right around the time he was going to take it to a shop to have it looked at ... he was suddenly laid off from work, due to Covid-19 and now so much time has passed.. hes decided to let it go.. but unfortunately doesn't have the time nor the money to have it looked at and repaired... so is going to have to sell it... as is condition., i told him i was interested, he gave me a killer deal under one condition...dont call him bitching if its something major, ( meaning its a Corvette, so be prepared ), i agreed to that.. But i said to him, if i have any questions about the vehicle you will give me answers to the best of your knowledge.. right.?.of coarse he said, im not going anywhere...call me anytime,,,,PLEASE NOTE::I grew up with this freind of mine, and totally trust him, i believe his story and know he will be there for me if i need him,,,,,So i had it towed over to another buddies home who is a semi retired mechanic said he take it on....So we already know that the car sat for over a couple years, the gas tank was near empty we put 20 gal of fresh premium , installed new battery ...the car lit up, but no crank, not even a sound...so we changed out the starter, got it to crank,, but wont start... at this point we realize it could be several things, but as we delved further into what could be causing this issue my partner realized the keys to the vehicle were without resisters...all of them...which we learned were required for all Corvettes that began in 1986 with a VATS installed... so i called my freind, the seller and inquired about the blank keys.. and he said those are the keys hes always used but to keep in mind that he was the third owner of the car...with that said ...my partner and i have been on the internet and have done a lot of research...so we thought before we begin a major troubleshoot, it might be wise to reach out to some Corvette people whom maybe we could get some friendly advice on, or what coarse of action or whats steps should be taken to try to get to the bottom of the problem and get the ol car up and running again.......care to chime in ? it whould be greatly appreciated....trust.....thank you

 

Being 'New to You' do you have the FSM (Factory/Field Service Manual)? Your friend owning the car as long as he did maybe he passed it on to you? Yes you do or NO?

If the car 'CRANKS' with a twist of the 'KEY' you DO NOT HAVE A BATS ISSUE! Your post could maybe use some punctuation and restructuring ..... It's a difficult read!

 

The Vats on the 86-89 is really simple, it is only a starter interrupt. So if you turn the key and it cranks, it is not a VATS issue. So on those cars a big failure is the ignition module but before you buy one, you need to see why it is not running. Compression, fuel and spark is all that is needed, what are you missing from those 3 and figuring that one out will figure out which direction to go next.

 

First of all, double check your battery cables and make sure they are tight and not corroded.

Like others said, since it does crank, it may not be VATS. However, if your 1986 Corvette previously started with a non-VATS key, then someone installed a VATS bypass/disable. 1986-1991 Corvette VATS ByPass Control Switch (zip-corvette.com). 1986-1989 Corvette VATS Disable Override Module (zip-corvette.com).... Look for these somewhere under the dash. If these were installed, it's possible something is bad or got disconnected from the VATS bypass.

 

Like someone said above, Suck, Squish, Boom, Blow.
so does it have Fuel pressure 35 PSI+- a simple quick redneck test if you push the test port does it hit ceiling, Does it have Spark, Does it have injector pulse,
If you give it a quick shot of starter fluid or gas does it run for a second or two

 

right. we have seen the starter relay contacts forced together bypassing the control side. Its rare but we have seen it.

 

Check/Clean the battery connections ! ... At BOTH ends ! .... Positive goes from the battery to the starter solenoid . Negative goes from battery to the block above the oil filter boss on the drivers side of the block .And don't forget that collection of fuse link wires that goes to the jump start terminal between the battery and the firewall .

 

Ok I was trying to keep this simple, the fuel disable is in the ECM not the VATS but since we are there we can go there. The ECM will get it's ground from the VATS decoder to turn on cranking fuel. I have been working on C4's since they were new and I have never seen this as a failure. The reason why the 86-89 VATS system is considered a starter interrupt is because that is pretty much all that it does. You can have a VATS failure and still start the car by using a jumper on the starter. The big difference was in 90 when the CCM had to enable the fuel injectors. So back to the original post question and let's not complicate this. Your issue is not VATS related, if the car is cranking then don't go down the VATS rabbit hole yet. Verify the other stuff, compression (last on the that list) verify your fuel pressure. It should pop up to min of 35 with just turning the key on and you should hear the pump. You can use a noid light on one of your injector harness plugs to verify that you are getting injector pulses as well. You can't use a test light for this, the test light will light up on both wires, the ECM pulls one of the powers to ground to fire the injector. Next check your spark, if it is non existent or weak this is more than likely your issue. The biggest issue I have seen is the module inside the distributor, make sure you replace with a GM one, do not get a replacement through a autoparts store, I have seen a bunch of these that are bad right out of the box. NOW worse case you seem to think this is VATS related on the fuel pump, then buy a new prom from Zip, Corvette Central, etc. All of the new or reprogrammed proms that they carry have VATS disabled from them. This will not fix your starter issue but fixes the cranking fuel issue if there is one but I doubt this is the issue. You need to look at the big 3 I and some others have mentioned. Don't overlook compression but make it last on the list, I have only had 2 C4's with compression so low they would not run.
Justin

 

Don't do anything until you go to YouTube and search for "cranks but won't start". You will find several videos but keep on looking till you find the one that answers all your questions and tell you what you need to do. It might tale a little time but it will be less time and money if you don't.
Goof luck.

 

The probelem with Youtube is that if you don't know what you are doing, you can get mislead very quickly by someone who made a video that also doesn't know what they are doing. The original service manual is also pretty good if you can read schematics.

 

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I don't see how your reply to my post contributes anything to this thread.

 

You of course are entitled to your 'opinion' that isn't disputed BUT yes U-tube can get many wandering off to ........................................ ............................

 

Damn, trying to tell you that in those videos if you don't understand what you are doing you don't know if someone else is giving you the correct directions in that video. Youtube is great if you have a really good idea what you are doing but there is a ton of stuff on it that is also not correct. That is all I was saying, when working with the VATS system it is really easy to go down a rabbit hole and spend a ton of money doing absolutely nothing that works, that is why simple is better. Compression, fuel, spark, figure out what is missing and you can narrow down the issue. I wasn't personally attacking you just making a comment about youtube.

 

Hey WVZR-1, thank you for responding... I took your request/ advise on restructuring my story/ post......to heart and after reviewing it, i agree went ahead and edited it, i hope i clarified things a bit better.................question...im not a mechanic so please be gentle.......NO i do not have a FSM... factory/ feild service manual but Im surly willing to buy one.....my mechanic said to get one, he could use it......but im a little confused ...is the Factory/ Field Manual the same as the Factory/ Shop Manual ? YES or NO

 

yes

**** I can't send you a PM or email but you should be able to do both using links by clicking on my 'user ID'. I can help you with the FSM and others.

 

To test if it is a fuel delivery issue spray starting fluid or brake cleaner into the intake manifold via the PCV hose fitting, if it fires up a few seconds it is a fuel issue.

 

Right on...great advise..Mr J.Abbott sir,..my mechanic and I both appreciate it.....thank you ps... if you dont mind ..we'll keep you posted

 

Hey WVZR-1....wow, what a nice gesture...thank you brother,.thats.way cool...well , it might be a while...maybe even a day or two...but Im quite certain we'll be getting back to you..ok?

 

If your mechanic has alldata or mitchell 1 the info is on there as well. A bunch of it has been disappearing so if you don't see a schematic or something you can ask them for it. I may have it as well, just let me know what you are looking for. Follow what was said above first, if by slim chance it is a VATS issue send me a PM, I will direct you around it so it will never be an issue again.
Justin