Fuel Pump Short?

[240nessx]

Hey everyone. So ive been fixing all the problems on my 240 since i bought it. Im up to the last problem for now and its a short of some sort to power i think. My fuel pump relay clicks as if its turning on the it will click again as if it turns off and will continue to do this while the car is off with the key out of the ignition. It will click continuously and drain my battery so my car becomes unstartable because of a dead battery. If i remove the relay the clicking stops and my battery stays charged. Anyone have any tips as to what to do? or can someone point me in a direction of where to start? Also, when the battery is charged and the relay is in the car starts no problem and i can hear the fuel pump start up, so the fuel pump. And when the relay clicks on and off or whatever its doing, the fuel pump doesnt turn on so its not like the car is trying to prime the engine every 5 seconds. Thanks for the help


**************************NEW QUESTION***************************

WHAT CONTROLS THE FUEL PUMP RELAY? After looking at the wire diagram. It could either be the Air Regulator Solenoid, the Power Transistor or the Coil, or i guess something else. But my question is now, What controls the Fuel Pump Relay

[OutToWinPAHC]

If the fuel pump relay or fuse isn't open its not shorted. I'd replace that relay as well as the accessory relay that feeds it.

[240nessx]

Ive already replaced the relay...it stopped for about a month then started back up again. I just looked at some Wire Diagrams and am wondering if its a component thats telling the relay to turn on and off. In the wiring diagram it says SMJ 11 or Air Reg Sol. I dont know what either of those are but ill look to see what they are now.

[FlipCoupe]

i was having the same problem, replaced the relays with relays out of my parts car and the clicking stopped but my battery is still draining -.- Lemme know what you find out

[240nessx]

lol ok, urs seems like it could be a different problem, ill let you know when i find out what it is. back to work on it...gonna see if wat i read will fix it lol

[240nessx]

WHAT CONTROLS THE FUEL PUMP RELAY? After looking at the wire diagram. It could either be the Air Regulator Solenoid, the Power Transistor or the Coil, or i guess something else. But my question is now, What controls the Fuel Pump Relay

[OutToWinPAHC]

Looking at the schematic in the EC section page 9. +12 from the ignition switch, through a fuse, to the relay power input, to the pump, out of the pump to ground. The relay positive is fed from the same positive fuse that feeds the pump, through the coil to the ECM. Trouble shooting section 39 is the fuel pump circuit.

Id check power to the fuel pump relay with a meter, have someone turn the ignition on, then off to see if goes away. If it does not shut off its not an ECU issue, because it should not have +12V. I might look into the ign switch,

[240nessx]

want me to upload the wire diagram i have? its for a 93 240sx, but it looks nothing like whats in the FSM. Only reason is becuase it doesnt show on my wire diagram that it comes from the ignition switch. It starts at the fuse but after the fuse its the same. The relay wires branch off after the relay and go to the Air Reg Sol, one goes to a Power Transistor, and another goes to the Ignition Coil. Only reason im not thinking its the ignition, because i can start the car no problem and the fuel pump primes its just the relay is getting power from the component that controls the relay. thanks for all the help tho btw, unless the ignition switch is what is controlling the fuel pump relay

[OutToWinPAHC]

FSM is in my sig, go to the EC section (fuel ad emmisions) Its like I said according to the FSM

[240nessx]

i dont think its the ignition switch because i have power to the relay. and if it was a short or open i wouldnt have any power to the relay at all. i see what u mean after looking at the fsm but, i think its something else

[OutToWinPAHC]

As per the FSM.... you shouldn't with the ignition switch off

[240nessx]

i dont get what you mean, but what im trying to say is, when the ignition switch is turned on the fuel pump works, but when everything is turned off the relay turns on through something that controls it. the fsm shows that when the ignition switch is on or started the fuel pump will start, so are you saying the car thinks the key is always in accessory or start, then tries to correct itself i guess and shuts it off...if thats what u mean, wouldnt u hear the fuel pump turn on when the relay turns on? because i already tried listening for that and the fuel pump doesnt turn on till i actually turn the key to accessory

[OutToWinPAHC]

I am saying with the key out there should be no clicking of that relay because it should not how power... unless there is something wrong with the switch.

No if it is clicking while running and you replaced the relay there could be something wrong with something that controls 104 and its turning the relay off and on. To isolate that... cut wire 104 and take it straight to ground if you cant source the issue.

[240nessx]

alright i get what u mean. Also, in the fsm in EC on page 24, it shows the ignition switch controls the ECM which then goes to control the Fuel Pump Relay. How would i be able to test if the Ignition switch is the problem?

[240nessx]

Well my problem was someone f*** with my wire harness and i have to replace my engine harness...if that doesnt solve the problem im done

[OutToWinPAHC]

Just take the relay wire from going to the ECU right to ground..... always one with ignition on

[240nessx]

I found my problem...it has nothing to do with the ignition...my wires were fried because someone f*** with it, theres splices and solder everywhere.

[maj Andres]

I'm having the same f*** problem! I'm not getting a ground from the ECU to my relay. f*** fuel pump isn't turning on.


OutToWinPAHC, would you say that it's safe to just run that ground to chassis ground until i can figure out why the ECU isn't sending that ground?

[OutToWinPAHC]

I see no problem doing this, a number of people have just hardwired the fuel pump. Most who swap need to do this, me being one.

[maj Andres]

Well I got the fuel pump working...but my car still won't start First time this has happened too