93 S-10 Blazer only starts with manual fuel prime

I have a 93' S10 Blazer, it's got the Vortec 4.3L CPI (Center Port Injection). The vehicle started running rough, problem was resolved by replacing the plastic fuel lines inside the intake manifold that feed the "spider". They were cracked and leaking excess fuel into the intake. After that, the truck ran great for about a week. Then we discovered one day, it simply wouldn't start. The fuel pump does it's start cycle, but the engine isn't getting it's initial prime of fuel to start. If we spray carb cleaner or any other combustible liquid into the intake, the truck will fire up and run like a charm. So basically, it's not automatically priming itself to initially start. After manual prime, starts no problems everytime, hot or cold. Could the fuel pump not be pushing it's correct psi, and need to be replaced, or could the "spider" be faulty? I'd like to narrow it down to just one of those problems because I don't have the money to replace both. Some feedback would be awesome, thank you!