Suburban 3/4 Ton 4WD V8-305 5.0L (1986)
Bowl Vent Valve: Testing and Inspection
1.
Disconnect carburetor bowl vent vapor hose.
2.
Using hand-held vacuum pump, apply vacuum to hose and note gauge reading. Reading should not be more than .5 inches Hg. If vacuum is greater
than specified, check for plugged hose or canister filter. If reading remains high, replace vacuum canister.
3.
With engine idling at normal operating temperature, again apply vacuum to vapor hose. The line should be blocked and a high vacuum reading
should be obtained. If line is not blocked, remove vacuum line from canister and check for presence of vacuum. If no vacuum is available, repair
line. If vacuum is available, replace canister.