Where is the pressure release valve for fuel line of a 1990 Buick Skylark?

The 1990 Buick Skylark doesn't have a pressure release valve specifically *on* the fuel line in the same way some systems might. Fuel pressure is regulated by the fuel pressure regulator, which is usually integrated into the fuel rail itself, or very close to it. There's no separate valve to manually release pressure.

To relieve fuel pressure, you would typically:

* Disconnect the fuel pump relay: This is the safest and most common method. This cuts power to the pump, allowing the pressure to bleed off naturally. Consult your owner's manual or a repair manual for the location of the fuel pump relay.

* (Less Recommended) Carefully disconnect a fuel line at the fuel rail: This is risky and should only be done by someone experienced with fuel systems, as fuel will spray out. Always have a rag and safety glasses ready. This is not recommended for the average person.

In short: There's no single "pressure release valve" to find. The process is to remove the power to the fuel pump to relieve pressure.