90 buick lesaber 3.8L

butchfig8

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#1
:-\ 90 lesaber, 20psi gas pressure, in process of changing gas filter, Is pump bad ?? never seen a pump put out 1/3 pressure ??
Alldata wire diagram, shows grey wire feeds fuel pump from fuel pump relay, Have no grey wire, not sure I am on correct relay.
diagram shows the relay on the passenger side firewall, pull that relay (only relay there) and eng contines to idle. ??
Eng will not run above idle and hard starting.
 
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#2
Fuel pressure should be 40.5 to 47 psi..Look under the dash on the passenger side..There should be about 7 relays..The fuel pump relay should be the middle one on the right side....Jim
 
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#3
as mentioned the pressure is very low, start with filter, check with new filter ...then unplug fuel pressire regulator vacuum, this would give full reading. But I think we know what you are doing this weekend....reccomend a AC Delco pump no aftermarket here.

GM's often use a redundent circuit to energize fuel pump, this parallel circit runs thru the oil pressure switch, therefore if engine has oil pressure removing relay would not lose fuel pressure............It appears the Elec system is operating OK.
 

Gus

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#4
As has been stated, disconnecting the correct relay will not turn off the car.....since the oil pressure switch is in parallel.....on a COLD engine disconnecting the relay would cause an extended crank until oil pressure builds up and closes the switch to the fuelpump....

If fuel pressure doesn't get up near 40 psi with a new filter, I guess it's pump time....