1997 GMC Safari Intermittent fuel pump not working

GENESISV

MEMBER
1997 GMC SAFARI

Electrical problem
1997 GMC Safari 6 cyl Two Wheel Drive Automatic 190K miles

Fuel pump does not prime. Seems to happen whether weather changes from dry to damp. Fixes itself by waiting for weather to dry out or usually by just rolling the car a few feet to "shake up" the system. Already replaced pump, relay and harness and checked as far as possible for bad wire/connection. Is there a pressure regulator that might be faulty? Where is it? Any other ideas?

1 Reply

JDL

MECHANIC
16,098 POSTS

Welcome, thanks for the donation, use a gage and check fuel pressure, If you have the spider fuel system, pressure is critical. I saw what you replaced, not sure what all you tested? There is an oil pressure switch in your fuel pump circuit, once you crank it enough to bring up oil pressure and the switch closes, the pump will run, even without the relay. As long as the switch is functional and the circuit has voltage.

With key on, no crank, you should hear the pump run for a few seconds, if not, check the relay circuits for voltage. Load side of relay is hot all the time, the coil side of relay gets voltage from pcm. Use a digital multimeter to check for voltage not a testlite.

The fuel pressure regulator should be under the upper intake manifold assembly.