I have brought a 1981 280zx turbo back from the dead. Well sitting 15 years. The motor runs smooth but I'm hearing 2 noises. The first noise is when I turn on the fuel pump it makes a noisy brake sound under the hood. Then as it's running it randomly makes a constant buzzing noise from around the intake area. I cant seem to pin point it. The pump is new and the noise isn't coming from the back. All 6 injectors are new and Ive never heard an injector make those noises. But there's the thing in front of the intake pressure pop valve that might be some kind of idle air thing. There is no cold start valve that I see on the intake. The fuel goes into the aftermarket fuel rail and back to the after market regulator then back to the tank. I think both noises might be related to the same issue but what could that be?

 

Noisy vacuum pump?

 

It sounds like from the intake side. It happens very randomly. It will.run smooth fo a while then this buzzing noise starts. It might last a while then go away or do it constantly. Isn't the vacuum pump on the passenger side near the vapor canister? It's hard to pin point exactly where at near the intake it makes the noise.