Fuel pump relay
 

Hello my purchased a Ls harnes from a Buddy of his a few years back. Its a High Performance Injectors LS Standalone wiring harness. Probably a PSI knockoff. The problem we are having is that I'm not getting any power from the relay fuse block for the fuel pump. The instructions stated that I needed to run a contant power wire to the 30 terminal on the relay and a wire to the 87 terminal of the relay. Which it will supply power up the fuel pump. Not sure whats going on. I wired another friends truck with the same harness and it powered up just fine. I did notice that on his fuse block relay there was a extra white wire that was jumped over to the other relay. Someone added that wire. When they first added the LS engine to his truck. Attached are 2 pics that show the underside of my son's fuel relay block and my friends fuel relay block.

Thanks,
Ramiro

Re: Fuel pump relay
 

Not knowing which is which on your block,....that looks messed up in your pic
This is how it should be
30...constant 12v power
87...to the fuel pump
86...switch on ,keeping 12v while on and cranking
85...ground

Re: Fuel pump relay
 

Mongocanfly, the first pic without the white wire is the one of my sons truck. If i'm correct now on what you posted. Maybe on the second pic maybe the ran that white wire to the 86 terminal to give it 12v? So terminal 86 needs 12v key ignition? the relay with the green wire is the relay for the fuel pump.

Ramiro

Re: Fuel pump relay
 

Like I said..since i dont know where the wires go from your relay...that looks messed up...
Pull all the wiring off those relays and redo it..
The fuel pump relay needs wired Independent
And yes...86 needs to have 12v with key on and while cranking

Re: Fuel pump relay
 

Mongocanfly would you happen nto have a diagram I can look that shows how both relays need to be connected. Also I need to findout which wire is coming form the ECM.

thanks,
Ramiro

Re: Fuel pump relay
 

I have the same harness, I'm pretty sure mine looks like the picture on the left. If mine wasn't mounted under the seat I'd get a closer look for you. Have you tried texting the manufacturer for support? They were good for somethings for me but not others.

In your pictures above, do you know which one is the fuel pump relay? Left or right? Which one did you insert a connector and run a wire to your fuel pump? I'm guessing it's the on on the right with the green wire.

The green wire should be the one that goes to PCM. Which PCM do you have? Blue/Green or Blue/Red? Either way that green wire should go to PIN 9 on the Green or Red connector.

Re: Fuel pump relay
 

I have labeled your picture.

Where are you getting your Key/Ignition switched power supply? On my harness it was a long skinny single red wire.

I think on my harness, I had to add both wires to the relay for the fuel pump. For example on your top right red wire. Say, I ran that straight to the battery(with a fuse or circuit breaker right by the battery) and then the bottom right black wire, I ran that to the fuel pump.

The PCM then sends 12v down the green wire, triggering the relay that then connects the top right wire with the bottom right wire sending power on to the fuel pump.

Re: Fuel pump relay
 

Jason I contacted the manufacturer they would not help me unless I produced a receipt that proved it was there harness.

Re: Fuel pump relay
 

Jason the top red wire on the relay to the right. That wire I connected to contanst power from my fuse panel. Also I connected the a long skinny redwire to key ignition from the fuse box panel as well. I will make sure on the skinny red wire im mgetting 12v when i turn the ignition on . Also I did add two wires to my relay per the instructions. I will look at my relays and make sure they are like what you labeled on my picture. Thank you.


Ramiro

Re: Fuel pump relay
 

I added the wording to the 2 wires I added

Ramiro

Re: Fuel pump relay
 

Jason we have the Green/Red connectors. Ill check Pin 9.

Ramiro

Re: Fuel pump relay
 

ok ..i believe i was getting your pics mixed up as to which is which..the computer im on now has them in order with what you said..my little pad had them swapped..haha
after looking at it more, the pic (your buddys truck) with the white jumper wire looks to be getting the fire signal from the fuel pump relay to fire the other relay....
not really ideal as the ecm fires the pump for a few seconds then stops waiting for a run signal...( i think thats right)..

on the one you say is your sons, that looks more right..
make sure your constant 12v power wire is hot to terminal 30
make sure your getting 12v key on and crank at terminal 86
make sure you have ground on terminal 85
if these are correct when the key is on you should have 12v at terminal 87..for a few seconds
when you cycle the key it should power the fuel pump for a few seconds, then it stops..and waits on the crank signal before firing the pump again
make sure your relay is good..
and you could momentarily put a 12v jumper wire from a known 12v source to the wire going to the fuel pump..it should run if its good

Re: Fuel pump relay
 

mongocanfly and Jason Banks thank you for all your help. I had it wired correctly. The problem was both relays were bad. I replaced it and the fuel pump primes up. Thanks again.

Ramiro

Re: Fuel pump relay
 

Wow, they must have cheaped out on the relays...

Re: Fuel pump relay
 

Jason I believe so. The truck wants to start but now we are having to trouble shoot the codes. The harness is a drive by wire. codes relating to the gas pedal and the tac module.

Ramiro

Re: Fuel pump relay
 

Well...glad you got that part behind you anyway..!!