Cant get fuel pump to turn on

[luckie2hav3her]

check all fuses and relays they all have power, ground has power, but for some reason when i turn the key to the on position i dont hear the fuel pump turn on.... i kno the main power wire is black yellow grey and it runs from the relay under the hood to the fuel pump, does it run anywhere else? like to the ecu or something?? any reason why u think my pump wont turn on?? thx in advance for any advice

[Pacman]

Ever think the pump itself is bad?

[idlafie]

check all fuses and relays they all have power, ground has power, but for some reason when i turn the key to the on position i dont hear the fuel pump turn on.... i kno the main power wire is black yellow grey and it runs from the relay under the hood to the fuel pump, does it run anywhere else? like to the ecu or something?? any reason why u think my pump wont turn on?? thx in advance for any advice

What year is your car again?? Do you have a FSM?? If not you may want to download one. If you trace the fuel pump circuit, you'll notice that the fuel pump get's it power from the fuel pump relay. The fuel pump relay in turn gets it power from the ECU, (the ECU sends out a ground signal to the relay), AND the ignition switch - the ignition switch sends a positive signal to the fuel pump relay while the ECU sends a negative signal to the fuel pump relay. If you DON"T get a negative signal from the ECU then you WONT get any power to the fuel pump relay = no power to the fuel pump.

You have two options....1). Run a new ground wire to the Fuel Pump relay, (cutting out the ground wire from the ECU), OR 2). Replace the ECU.

ID

PS:
This applies to S14's.......

PSS:
Somewhat related topic....R240NA gives some good info....
http://www.zilvia.net/f/showthread.php?t=82320

[luckie2hav3her]

hmm ok well ignition works and ecu as well.... i was thinking that the wire running from the relay to the pump is fucked up somewhere along the way, so i was thinking of replacing the power wire from the relay to the pump, as for the ground... will cutting it from the ecu affect the ecu in anyway?? i can just ground it to the chassis in the engine bay right? and yea i do have a FSM jus dont kno how to read it =P

[luckie2hav3her]

oh and its a 98**

[idlafie]

hmm ok well ignition works and ecu as well.... i was thinking that the wire running from the relay to the pump is fucked up somewhere along the way, so i was thinking of replacing the power wire from the relay to the pump, as for the ground... will cutting it from the ecu affect the ecu in anyway?? i can just ground it to the chassis in the engine bay right? and yea i do have a FSM jus dont kno how to read it =P

Before you cut any wires, plug a test lead into the negative output wire from the ECU. Plug that test lead into your multi-meter tool & see if you get a signal out from the ECU. IF you get a negative ground signal out from the ECU, then you know the ECU is good. Don't be fooled by all the bulbs on your dash lighting up when you flip your ignition switch to the ON/START position. The negative ground signal on your ECU can go bad taking out your fuel pump without affecting any other functions on the ECU.
You're gonna have to test EACH section of wiring individually before you can trace the source of your problem. It's a pain in the ass to do, but once you figure out what the source is, fixing it is a piece of cake.
Anyhow, good luck....you're gonna need it!!
ID

[luckie2hav3her]

done and done!! ran another wire directly from relay to pump, and it turned on! runs like a charm!! time to piece my car back together =P