Fuel pump relay help - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Tranman324 · 08-16-2010, 08:42 PM

I have an redtop S13 SR in an S13.

So the fuel pump relay isn't clicking over.

I've tried 5 different relays, so the relay isn't the problem.

Currently, I'm using a jumper to get the car running. Like so:

So I think the relay is set up like this...

Pin 1: Some power?--- I think this could be the problem
Pin 2: Ground? --- it goes to Pin 104 on the ECU
Pin 3: Fuel pump
Pin 4: Power?

Now... After some hard searching, I may have a ground loose somewhere? I'm going to check tomorrow afternoon.

I don't want to just run the jumper, because I like to keep things done the right way.

What do you guys think?

Sileighty_85 · 08-16-2010, 09:16 PM

http://zilvia.net/f/tech-talk/327189...-problems.html

No harm in checking

Tranman324 · 08-16-2010, 09:25 PM

Yeah, you're right. I'll check it out, but I know my harness is brand new and just done and when I installed it, the brown plug looked like it was in good condition.

Car has only been driven for maybe 12 miles.

Sileighty_85 · 08-16-2010, 11:09 PM

its on the chassis harness side not the engine harness side.

Mine looked fine as well on the outside but it was corroded on the inside of the plug

Tranman324 · 08-17-2010, 09:26 PM

Alright, here's what I've got today....

First off, I checked the wiring on my plugs (The brown and Big grey plugs) that connect the engine harness to the body harness
- I found on the brown plug I got the Black/purple stripe and Black/Yellow stripe wires flipped when I re-pinned the plug.

- If I am correct, The black/purple stripe is the fuel pump relay and the Black/yellow stripe is the IACV.

- I plugged everything back up hoping it'll work, but the fuel pump relay didn't click over. Although, my Idle was fixed.

Here's the relay I'm using:

I have 5 spares of these, I've tried them all. All with no luck

Here is where the relay goes for reference purposes:

Labeled 1,2,3, and 5 like how its labeled on the relay.

This is what I know(think) about the relay:
Pin 1: goes to Pin 104 on the ECU
Pin 2: goes to the fuel pump
Pin 3: Maybe ground?
Pin 5: Power

Now, continuing my diagnosis of the problem I started with checking pin 104 on the ECU (black/purple stripe).
- with my multimeter, Positive probe on the wire and negative wire on a local ground on the chassis
- With the relay OUT and the ignition ON, I got NO VOLTAGE
- With the relay IN and the ignition ON, I got 11.54V. The voltage was constant and did not change, I waited for about a minute to see if it changed.

Next, I checked continuity from Pin 104 to the relay, positive probe on pin 104 and the negative on a Pin in the relay (pin 1,2,3 or 5)
- from Pin 104 on the ECU to Pin 1 on the relay: POSITIVE for conitnuity
- from pin 104 to pin 2, 3, or 5: NO CONTINUITY

I also checked the continuity from Pin 2 on the relay to the Fuel pump: POSITIVE for continuity

The voltage from Pin 2 and 5 is 11.57 V, which makes sense since those are the 2 pins I'm jumping to get the pump to run

When I ground Pin 3, I get 11.56 V

And.... now I'm lost. what now?

Sileighty_85 · 08-17-2010, 10:21 PM

Its gonna be hard for me to explain this, so bare with me.

#1 & 2 are for the Coil that will close the contacts when energized (ECU will Energize this)
#3 & 5 are the contacts that will close when the coil is energized (battery power flows through)

the ECU will energize the relay coil & Power will flow through 3 & 5

from pin 104 to that relay you will only get one terminal with continuity, so that normal

What do you mean when you ground pin 3?
you mean one lead to Pin 3 and one to ground?

You should have

1 Nothing
2 12V
3 12V
5 0V

Almost sounds like your ECU is at fault

Tranman324 · 08-17-2010, 10:50 PM

Quote:

Originally Posted by Sileighty_85

What do you mean when you ground pin 3?
you mean one lead to Pin 3 and one to ground?

You should have

1 Nothing
2 12V
3 12V
5 0V

Almost sounds like your ECU is at fault

Yeah when I put one lead on pin 3 and the other to a ground.

I was hoping it wasn't my ECU, didn't want to say it. I think when I got the wires switched, it may have killed that circuit.

08-16-2010, 09:16 PM	#2
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	http://zilvia.net/f/tech-talk/327189...-problems.html No harm in checking __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

08-16-2010, 11:09 PM	#4
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	its on the chassis harness side not the engine harness side. Mine looked fine as well on the outside but it was corroded on the inside of the plug __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

08-17-2010, 10:21 PM	#6
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	Its gonna be hard for me to explain this, so bare with me. #1 & 2 are for the Coil that will close the contacts when energized (ECU will Energize this) #3 & 5 are the contacts that will close when the coil is energized (battery power flows through) the ECU will energize the relay coil & Power will flow through 3 & 5 from pin 104 to that relay you will only get one terminal with continuity, so that normal What do you mean when you ground pin 3? you mean one lead to Pin 3 and one to ground? You should have 1 Nothing 2 12V 3 12V 5 0V Almost sounds like your ECU is at fault __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

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08-16-2010, 08:42 PM	#1
Tranman324 Zilvia Junkie Join Date: Jul 2006 Location: Marietta, GA Posts: 355 Trader Rating: (11) Feedback Score: 11 reviews	Fuel pump relay help I have an redtop S13 SR in an S13. So the fuel pump relay isn't clicking over. I've tried 5 different relays, so the relay isn't the problem. Currently, I'm using a jumper to get the car running. Like so: So I think the relay is set up like this... Pin 1: Some power?--- I think this could be the problem Pin 2: Ground? --- it goes to Pin 104 on the ECU Pin 3: Fuel pump Pin 4: Power? Now... After some hard searching, I may have a ground loose somewhere? I'm going to check tomorrow afternoon. I don't want to just run the jumper, because I like to keep things done the right way. What do you guys think?

08-16-2010, 09:25 PM	#3
Tranman324 Zilvia Junkie Join Date: Jul 2006 Location: Marietta, GA Posts: 355 Trader Rating: (11) Feedback Score: 11 reviews	Yeah, you're right. I'll check it out, but I know my harness is brand new and just done and when I installed it, the brown plug looked like it was in good condition. Car has only been driven for maybe 12 miles.

08-17-2010, 09:26 PM	#5
Tranman324 Zilvia Junkie Join Date: Jul 2006 Location: Marietta, GA Posts: 355 Trader Rating: (11) Feedback Score: 11 reviews	Alright, here's what I've got today.... First off, I checked the wiring on my plugs (The brown and Big grey plugs) that connect the engine harness to the body harness - I found on the brown plug I got the Black/purple stripe and Black/Yellow stripe wires flipped when I re-pinned the plug. - If I am correct, The black/purple stripe is the fuel pump relay and the Black/yellow stripe is the IACV. - I plugged everything back up hoping it'll work, but the fuel pump relay didn't click over. Although, my Idle was fixed. Here's the relay I'm using: I have 5 spares of these, I've tried them all. All with no luck Here is where the relay goes for reference purposes: Labeled 1,2,3, and 5 like how its labeled on the relay. This is what I know(think) about the relay: Pin 1: goes to Pin 104 on the ECU Pin 2: goes to the fuel pump Pin 3: Maybe ground? Pin 5: Power Now, continuing my diagnosis of the problem I started with checking pin 104 on the ECU (black/purple stripe). - with my multimeter, Positive probe on the wire and negative wire on a local ground on the chassis - With the relay OUT and the ignition ON, I got NO VOLTAGE - With the relay IN and the ignition ON, I got 11.54V. The voltage was constant and did not change, I waited for about a minute to see if it changed. Next, I checked continuity from Pin 104 to the relay, positive probe on pin 104 and the negative on a Pin in the relay (pin 1,2,3 or 5) - from Pin 104 on the ECU to Pin 1 on the relay: POSITIVE for conitnuity - from pin 104 to pin 2, 3, or 5: NO CONTINUITY I also checked the continuity from Pin 2 on the relay to the Fuel pump: POSITIVE for continuity The voltage from Pin 2 and 5 is 11.57 V, which makes sense since those are the 2 pins I'm jumping to get the pump to run When I ground Pin 3, I get 11.56 V And.... now I'm lost. what now?