GM Storm/Spectrum 1985-1993 Repair Guide

General Information


The non-turbo Spectrum is the only vehicle covered by this guide which uses a carburetor to deliver fuel to the engine. The remaining vehicles use a fuel injection system, covered later in this section.

The Spectrum carburetor is a downdraft fuel and air metering device with 2 stages of operation. The primary side uses a relatively small bore, double venturi and a bridge nozzle. Primary fuel metering is accomplished using a duty (mixture control) solenoid.

The secondary side of the Spectrum carburetor has one large bore and a secondary main metering system. The metering system supplies fuel to the engine during heavy load conditions.

The Engine Control Module (ECM), which monitors the engine emission system, uses information gathered from various sensors to control the air/fuel ratio. Based on feedback from the oxygen sensor (and other related sensors), the ECM will vary signals to the mixture control solenoid located in the carburetor to control primary side fuel delivery.

The remaining fuel system components are the fuel tank, lines/hoses, inline fuel filter and the mechanical fuel pump.