how to test fuel pump?

[Kane1975]

Hi to everyone here. I have a 1994 or 1995 subaru impreza with the 1.8 non
turbo engine that has developed a fuel related problem.
it seems to be the fuel pump but i am not 100 percent certain. when the key
is turned on to acc I do not hear the fuel pump and if I throw some fuel
down the intake she will start immediately.
there are four wires leading to the tank. 2 of which must be for the sender
unit and the others to power the pump itself. I measured the power using a
multimeter and one pair of wires was around 12V and the other pair was only
about 4V from memory. I am not sure which wires are the fuel pump as yet.
based on the voltages can anyone help?
also if anyone can suggest how to safely test the pump itself would be a big
help. i am hesitant to apply 12V straight to the pump until I know the
correct voltage.
i do not want to go out and buy another pump until I can confirm beyond
doubt that the fuel pump is the real problem. For all I know it could be the
efi or engine management stuff that is stopping the fuel delivery and not
the pump? if anyone has some experience with this and can suggest how to
tackle this problem i would be very grateful. thanks

 

[gotbent]

Hi to everyone here. I have a 1994 or 1995 subaru impreza with the 1.8 non
turbo engine that has developed a fuel related problem.
it seems to be the fuel pump but i am not 100 percent certain. when the
key
is turned on to acc I do not hear the fuel pump and if I throw some fuel
down the intake she will start immediately.
there are four wires leading to the tank. 2 of which must be for the
sender
unit and the others to power the pump itself. I measured the power using a
multimeter and one pair of wires was around 12V and the other pair was
only
about 4V from memory. I am not sure which wires are the fuel pump as yet.
based on the voltages can anyone help?
also if anyone can suggest how to safely test the pump itself would be a
big
help. i am hesitant to apply 12V straight to the pump until I know the
correct voltage.
i do not want to go out and buy another pump until I can confirm beyond
doubt that the fuel pump is the real problem. For all I know it could be
the
efi or engine management stuff that is stopping the fuel delivery and not
the pump? if anyone has some experience with this and can suggest how to
tackle this problem i would be very grateful. thanks

 

[gotbent]

Hi to everyone here. I have a 1994 or 1995 subaru impreza with the 1.8 non
turbo engine that has developed a fuel related problem.
it seems to be the fuel pump but i am not 100 percent certain. when the
key
is turned on to acc I do not hear the fuel pump and if I throw some fuel
down the intake she will start immediately.
there are four wires leading to the tank. 2 of which must be for the
sender
unit and the others to power the pump itself. I measured the power using a
multimeter and one pair of wires was around 12V and the other pair was
only
about 4V from memory. I am not sure which wires are the fuel pump as yet.
based on the voltages can anyone help?
also if anyone can suggest how to safely test the pump itself would be a
big
help. i am hesitant to apply 12V straight to the pump until I know the
correct voltage.
i do not want to go out and buy another pump until I can confirm beyond
doubt that the fuel pump is the real problem. For all I know it could be
the
efi or engine management stuff that is stopping the fuel delivery and not
the pump? if anyone has some experience with this and can suggest how to
tackle this problem i would be very grateful. thanks

This is just a hypothetical answer, as it involves a flammable liquid,
possibly under pressure...if you disconnected the fuel line at the fuel
injector rail, and stuck it into an empty fuel safe container and had
someone crank the engine for a couple of seconds, fuel should squirt into
the container. This won't answer questions about fuel delivery pressure or
volume, but might be a way to tell if the pump is delivering any fuel. Be
careful. You assume all Darwin consequences if you actually try this.
Please don't even think about doing it in your garage.