Corsica L4-121 2.0L (1988)
Fuel Tank Pressure Release Valve: Testing and Inspection
This is a functional check of the TPCV valve to see if the diaphragm is leaking.
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Use a hand vacuum pump with a gauge and apply 15" Hg of vacuum to the tube labeled "CONTROL VAC." The diaphragm should hold vacuum
for at least 20 seconds. If it does not, replace TPCV valve. If it does hold vacuum proceed to next step.
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Apply a short hose to the tube labeled "TANK," and with vacuum still applied, blow into the tube. If air passes through the valve, then TPCV
valve is ok. If no air passes through the TPCV valve then it is bad.
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With the short hose still attached to the tube labeled "TANK," blow into it again but this time with no vacuum applied to the tube labeled
"CONTROL VAC." If diaphragm pops and air passes through the TPCV valve then the valve is ok. If very little air passes through the valve the
valve is still ok. If no air passed through the TPCV valve then it is bad.
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NOTE: Pressure that is being blown into the valve must exceed the opening point of the valve
which is being held shut by a spring.
