I picked up this 91 Z28 project that had been sitting for 20 years. Fuel tank was replaced and new pump. It will only run for a second and stall. I can hear the fuel pump running it will only stay running on carb cleaner. It will start right back up and then stalls within seconds some people tell me to replace the fuel injectors other people say replace the module then they say the Vats. Security light does not stay on or blink. I don't want to throw Parts at it until somebody can say hey I had that problem and I did this.

 

First thing is to check out the basics... This is either a fuel problem or a spark problem.

Do you have access to a fuel pressure gauge? If so, hook it and monitor fuel pressure while it's running. Are you getting correct fuel pressure at all? If so, do you see a precipitous drop in pressure right before it stalls?

If the fuel pressure checks out...

If you have access to a timing light, you can hook it up to the coil wire. Run the car and fire the timing light at something (firewall, inner fender, etc... just so you can easily see the flashing... you're not trying to measure the ignition timing, just demonstrating that the coil is actually firing). If you see the flashing of the timing light stop right before it stalls, then it likely indicates that either the coil is bad, or the triggering circuits for the coil is bad (or maybe both)... i.e., the ignition module, or it's losing 12V to the primary side, bad ground etc...

 

If the car was sitting for 20 years I would be pretty surprised if the injectors were working properly

 

Also, think about the fuel filter... if that wasn't replaced, residual fuel in there could have turned to sludge after 20 years...

 

Second what @southbay08 said. Varnished shut and if multecs they suck.