Tuning up the 1990 Suburban 3/4-ton's 5.7-liter V-8 involves the replacement of several components. The most common components to replace during a tune-up are the spark plugs, spark plug wires and the air filter. This proper maintenance will ensure that your K1500 is running properly for years to come. Using the correct tune-up specifications assists in making this process as precise as possible.
The 1990 Suburban's 5.7-liter requires AC Delco spark plugs with the part number CR43TS, however, they can be cross-referenced to another brand, if needed. These plugs must have a gap of .035 inches and the gap must be checked prior to installation. When installing the new spark plugs, they must be torqued to 11 foot-pounds.
The spark plug wires can be picked up at any parts store and are pulled off and pushed on by hand. As you pull off each spark plug wire, make certain you replace it with a new one immediately to avoid mixing up the firing order. The firing order of the 5.7-liter is 1-8-4-3-6-5-7-2 and the distributor rotates clockwise. The cylinder numbers working from the front driver's side and going counterclockwise around the engine are 1-3-5-7-8-6-4-2.
The air filter is housed on top of the engine in a circular metal housing. Remove the nut at the top of the air filter housing and pull the cover off to access the air filter. When reinstalling the air filter cover, make certain to torque the nut to only 18 inch-pounds to prevent breaking the stud.
