Feul pump rewire problem

[TSi90Awd]

I have been having some problems with the stock wiring for the fuel pump in my car. I bought the rewire kit from forced performance because of this. I installed it today and still nothing. I don't even hear the pump kick on. I'm currently waiting on my friend to get a test light and I'm going to check and see if it's getting any current at all (which I don't think is likely because of how simple the rewire system is). Does anyone have any ideas as of what could be wrong?? I'm about to freakin' flip out over this fuel ordeal!! Any thoughts or help would be greatly appreciated.

 

[Quasimondo]

If your stock wiring is giving you trouble, then rewiring the pump won't fix it. That's because the wire that was supplying the voltage to your fuel pump is now energizing the coil to the relay that brings in power directly from the battery. If the coil isn't energized, then the relay stays off and your pump gets no juice.

You need to track down if the old fuel pump power wire is broken or corroded beyond repair. If you have a wiring diagram handy, you can just take some 14 gauge wire and run it from the rewired relay to wherever the supply voltage is coming from.

 

[TSi90Awd]

Where is the voltage supply coming from?? Directly from the battery?? If so, do I need to run the wire from the relay directly to the battery on the negative terminal?? Thanks for the quick response.

 

[Quasimondo]

The fuel pump before the re-wire modification gets its juice from the MFI relay. That relay is located in the engine bay, I believe. If you were having problems before the re-wire, check the relay to make sure it's still good. The power from the MFI relay goes out from a black/green stripe wire, but by the time it reaches the pump it changes to black/white stripe.

Check the MFI relay first before you run another wire there from the re-wired relay.

Chilton's has a good wiring diagram if you get lost trying to figure this stuff out.

 

[steve]

And the MPI relay is controlled by the ECU.

Perhaps if you explained how your pump doesn't work and what you have checked we can give you some ideas.

Steve

 

[TSi90Awd]

Well, the thing had been blowing relays like crazy, so I figured that the stock wiring was shorting out somewhere. I didn't realize that the rewire kit utilizes the old wiring for power, so now I want to bypass the old wiring (for power) completely. The fuel pump isn't getting any juice at all. I was thinking about using the setup that's on vfaq and running some 14 gauge wire from the battery to the relay with a fuse in between the two. Would this be possible?? Also, on the forced performance rewire kit, there is a green wire that plugs into thefuel pump test connector. Is this where the car is getting it's power from or what is this used for in the first place?? Thanks for the feedback guys.

 

[steve]

Done right the only thing the rewire does is get the signal to switch the relay from the old factory wiring, not power and connected to the fuel pump from the relay.

You fuse and run a 10 gauge wire from the battery to the back of the car. The fuse should be close enough to the battery that if the wire split at the fure it wouldn't be long enough to touch any metal parts and short. A 10A or 15A fuse should be fine for most pumps.
This is where the relay get's power from, to switch to the fuel pump.
You run a ground wire for the relay coil to the body.
You cut the factory power wire to the pump and connect the part going to the pump to the switched output of the relay. The part of the wire that runs back to the MPI relay, you connect to the coil input of the relay.

So when the factory wiring would have powered up the pump, it instead feeds power to the relay coil and throught the coil to ground. This switches the contacts in the relay connecting your new power feed wire to the fuel pump.


The fuel pump check connector is just a tap off the wire running from the MPI relay to the fuel pump. It's normally used to connect a jumper to the + battery terminal to bypass the ignition and MPI relay and power up the pump to test the pressure and check for leaks.

Hopefully, understanding how it's ment to work will help you figure out what's wrong with your setup.

Steve