Hi and thanks. I am seriously thinking of switching from the TBI on my 1991 RS, 305 V8 and 5 speed manual to a carburetor. Not exactly sure where I would go and what I can remove from the engine bay to make this happen. The VAT system is driving me nuts. I have the starter relay bypassed, but of course you need a signal from the ECM to fire the injectors and make it run. The resistor bypass only worked for a couple months. I figure with a carb the ECM and VATs becomes obsolete as you can wire the fuel pump to run as needed with a pressure regulator.
Please let me know if what I am doing makes sense.
Thanks.

 

Ive been running one of those $20 ebay VATS bypass for 2 years without an issue. It doesn't use a resistor tuned to the original key. It just sends the signal the ECM is looking for.

A lot simplier then a tbi to carb swap, if that is the only issue you are having.

 

Please post up a link to that resistor for us.

 

I wouldn't call it a resistor........its a signal generator I guess.

Price has went up, but this is what Ive been running. Just splice it in and go. $20 shipped http://www.ebay.com/itm/GM-VATS-or-P...1WEYiu&vxp=mtr

Havent had any issues so far.

All you have to do is wire it in and bypass the starter relay (which the OP has already done)

EDIT: I know it works on my 91 TBI. I don't even have the key cylinder in the car, just the ignition switch, and so far no issues. I installed it because I had a couple no start problems because of the VATS.

 

I have also used this exact VATS bypass module in my build. Really simple to wire in. This was on a '91 TPI car, but it should work on anything that has VATS (and a passkey module).

The only issue I had was trial and error to determine whether I needed a 30Hz or 50Hz signal. I wound up trying the wrong one first, of course.

 

I actually have a picture (I know, looks hideous, I was testing ok). It's the little black blob in the center of the shot.

 

Pretty sure I done the same thing! I should have wrote it all down when I done it.

I've got it all taped up right now, but if I ever have to pull it back out, I'll write it down.

 

I got as hold of Brain at Harris Performance and he said to send him my stock chip and he will delete the VAT system off the chip. I will give this a try and let you all know. I hope it's $60.00 well spent for a little bit of confidence in the car. www.tbichips.com

 

I have had the VATS proble, trying resistors from Radio Shack was the solution. Cheap, only took a couple of hours.
I have converted an LO3 from TBI to carb, don't do that. I just posted a new thread in TBI about that, go read it.

 

Thanks Cosmic. I am eagerly awaiting my re-programmed chip that eliminates the VATs completely.

 

Installed the reprogrammed chip today and the car started right without any issues. The security light is on permanently so I will need to find the bulb/wire and remedy that problem. Now it's on to other projects on the car.