LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Pontiac >> 1966 >> GTO Eng CD WS, Not Available Trans >> Repair and Diagnosis >> Engine Performance >> Fuel Delivery >> Mechanical Fuel Pumps >> Testing Vacuum Pump >> Vacuum Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Vacuum Test

CAUTION: Do not plug pump outlet line, this line must be open whenever pump is operated.

First check operation of windshield wiper motor and lines by disconnecting inlet and outlet lines at pump and connecting these lines together (to by-pass pump). Operate engine at speeds up to 1000 RPM. Wiper should operate at full speed.

NOTE: A dry windshield will slow down action of wipers.

To check vacuum pump, disconnect pump outlet line at intake manifold and plug manifold fitting. Disconnect pump inlet line and connect a vacuum gauge at pump inlet fitting. Operate engine at 500 to 1000 RPM and note gauge reading. Vacuum should be approximately 14" to 19" Hg.