Full pump runs continuously

[Jim Whiting]

I gave a 1998 volvo penta 5.7 when you turn key on the fuel pump starts pumping as if at full throttle. It does not start pumping. Changed relays but problem continues. Any suggestions

 

[alldodge]

Don't know which 5.7 motor but will assume it has a carb
VP uses 2 diodes (Dumb IMO) which allows power to energize the relay when cranking and ones started, power comes from the alternator to keep it energized. The most likely issue is the ALT diode has shorted.

Put a meter on pin 85 of the relay and see if it has power as soon as key is turned ON