85 model cutting out and not restarting.

[steve_79]

Hi guys.

Just having a bit of trouble with my 85 mod. Apparently the vats system came out in 86 and mine shouldn't have it. However, i have had the codes pulled by the local auto electrition and came up with a 46 Vats failure.. Bit sus to me.

The problem is, i dont have a key with the pellet and it cuts out while driving and will not restart (will crank but not fire)untill i shift to park and turn the key completly off, wait about 5 seconds and start again. Sometimes it works first go but sometimes it takes about 10 attempts (not good on a single lane road with traffic).

All the experts out here can tell me is i need a key with the pellets, but everyone on digital corvettes says 85 models don't have vats (reffer to error code 46 vats failure).

This problem is now starting to occour alot more often and is getting quite annoying. Any help would be muchly appreciated.

Thanks

Steve.

[Thunder Kiss]

Hi Steve,

I don't know the answer to your problem but here is what I do know.  The VATS system came out in the 1986 model year, however cars built in the final few months of 1985 are classed '86 models.  An easy way to tell an '86 from an '85 is by looking for a high mount brake light up on the roof.  '86s also had ABS brakes, a thicker steering wheel and, as you mentioned, a pellet in the key for the VATS system.

I have an '86 and have first hand knowledge of what happens when the VATS system plays up - the car goes dead - it won't even crank when you turn the ignition!  The fact that you can get the starter motor to crank makes me think it may not be VATS - even if your car was an '86.  

Also, if VATS stops your car from starting, you must wait several minutes (like 4 or 5) before attempting a restart otherwise it will automatically stop you for another 4 or 5 minutes.  Again, the fact that you can restart after 5 or 10 second seems strange if it is a VATS issue.

My car will not start in neutral either, it must be in park.  This may be a standard "feature" of C4s but I'm not sure.

A code 46 is indeed a VATS circuit problem - so I'm stumped!
I would probably start looking at the ignition system, maybe a lose wire somewhere? Dud terminal in the distributor or coil?

[77CVT]

Was a code 46 a standard VAT error for all C4's?

This may not be of help but I had a starting problem similar and turned out to be a bad earth cable.  Easy test is to put jumper cable from -ve battery to the engine block.

Might be one more problem to eliminate?

[87Z51]

He has not got a starting problem which removes VATS , starter cable, etc.

If cranking OK Only need two things to fire; spark and fuel.
the fact that it cuts out after starting means he has lost one or the other.
Most likely fuel system
After it cuts out
Can you smell raw fuel out the exh pipes when cranking?
Can you hear the fuel pump run when you turn the key on before cranking?
If so fuel pump is working

If not  check fuel electronics.
Pump relay could be dodgy (old age) ,Mine had similar problem
On the early models  the connector that plugs into the pump relay  looses the insulation and can short or not make contact intermitantly.
Need to have a volt meter handy when it happens so you can check.

As stated
Confirm you have spark at the plugs , std test ,pull one plug wire and get someone to see if it sparks while cranking.

Where are you located?
Prob have a spare relay you can borrow to test

[77CVT]

Faulty coil?  Change caps with someone else's.  

Does it cut out at idle or at higher fuel demands?  Hard to believe but some cars haven't had a new fuel filter for years and years!

[steve_79]

Ok guys.

  With cameron and the shop manual's help i think we've got it nutted.

     When you start the car the fuel pump relay is only triggered by the computer for a short time. After that time power for the fuel pump comes from the








   Oil pressure switch..

  Haven't proven that to be the problem yet but we bypassed it with a wire and all seems to be well. I have a new one ordered and will let you all know when i get it installed.

  Thanks for all the help.

   Once again, a big thanks to cameron who never seems to have a problem helping out his fellow vette owners.      THANKS MATE

  Steve

[Cameron 77C3]

Good news Steve.  Thanks for the kind words.  So I gather you got to Gouldburn OK?

Keep us posted.