V 3500 P/U 4WD V8-350 5.7L VIN M 4-bbl (1987)
![background image](/gmc/v_3500_p/u_4wd/v8-350_5.7l_vin_m_4-bbl/Page-680002.png)
3.
Blow-by at maximum capacity of regulator valve.
4.
Plugs from kit or engine vacuum lines are not properly sealed.
5.
Tester knob improperly set.
Yellow & Red
1.
Regulator valve or system partially or fully plugged.
2.
More engine blow-by than regulator valve can handle.
3.
Vent hose plugged or collapsed.
Red
1.
Regulator valve or system fully plugged or stuck.
2.
Vent hose plugged or collapsed.
3.
Extreme blow-by.