Tank Pressure Control Valve (TPCV) Check

Remove the TPCV from the vehicle. Attach a hose to the fuel tank port of the TPCV and blow through it. A resistance should be felt until enough pressure unseats the diaphragm at which time flow increases.

With a hand pump, apply vacuum (15" Hg. or 51 kPa) to the upper tube (manifold vacuum supply port) of the TPCV. If the diaphragm does not hold vacuum for at least 20 seconds, the diaphragm is leaking, and the TPCV must be replaced.

If the diaphragm holds vacuum, try to blow through the hose connected to the lower tube while vacuum is still being applied. An increased flow of air should be observed. If not, replace the TPCV.