'89 C3500 TBI 7.4 Injector Problem

[Tow Truck Man]

Hello everyone,

I hope that I can get some help with this problem. I have a '89 C3500 7.4 TPI I purchased a couple of weeks ago. When I got it it was running but needed some work. I changed the vacuum lines on the carb, put in new plug wires, new gas filter and a new battery and then tried to start it up again and have a problem.

Problem is that when cranking the ignition the injectors pulse fine but when it's started and the key is let back to on position the injectors stop spraying gas and thus it dies. If I spray starting fluid into the throttle body it'll stay running.

Any help would be greatly appreciated!