Local Yokel

Thanks. Feel free to steal it and post it wherever it's needed ....

rm9792

I got mine right from the Ford dealer (tommie vaughn) and the colors were jacked. I just matched up best I could and it works so far.

157dB

Its a simple resistive sender.
The wires will work hooked up either way.

kentompkins

Ok. To close this one out. Here is how it ended up.

While I agree that it is a simple resistor - it did, in fact, make a difference how I had it hooked up.

1) First I had it such that the colors of the wires removed from the original plug were in-line with the wires in the new plug. That meant it was LB/YE across from LB/YE and LG/VT across from LG/VT. In this configuration the system worked in that fuel was delivered, the gauge reacted and no DTCs were thrown. HOWEVER, the gauge inaccurately read low. I had about an 1/8th of a tank when I started. I added 6 gallons. The gauge only read just over 1/4 of a tank.... low.

2) Second I had it such that the colors of the wires were opposite. OS it was LB/YE in-line with LG/VT and vice versa. In this setup, everything worked as it should and the gauge correctly read just under 1/2 a tank.

So, in summary, looks like some drunkards on Friday afternoon did a batch of GT500 fuel pump wiring. Beware of these. You'll know you have them because they have wires on the wrong side of the grommet.

hammeron

glad you got it all worked out kentompkins.

the wiring has been a known issue for awhile
now and just recently it stumped tillman speed
until they figured it out.

there was apparently quite a few of these kits
that were wired differently than the instructions
show.

anyhow, now you can help the next guy who ends
up in this mess.

Diabolical!

Normally, I'd agree with you, but my kit had the two sending wires installed backwards (and this was in the old kits a couple of years ago). After spending the better part of a day trying to figure out why my fuel gauge was reading empty, I swapped the wires on a whim. Bam, fuel gauge registered properly. I can't explain it, but it worked. Been that way ever since.

joneil

Do you have a solution yet?
I'm in the process of doing the same thing, installing a GT500 fuel system (before installing stage 2 Edelbrock supercharger on my 2010 Mustang GT). This afternoon I installed the fuel pump assembly and was now addressing the unpinning of the 2 wires. The only instructions I've seen for the install are up through 2009 Mustangs, so unless you've found something otherwise, the instructions don't quite match for a 2010 ... close, but not a real match. Anyway ... my wire colors are a little different than yours, but here's what I've concluded. The connector (4-pin) going to the single fuel pump consists of 2 larger diameter (gauge) wires and 2 smaller gauge wires. The larger wires provide power to the pump motor. The smaller wires (after looking at the single pump I removed) are for the fuel level sensor. The sensor is a variable resistance sensor and as such is doesn't matter (my assertion) which is connected to which, as long as a circuit is completed with the level sensor variable resistor. One of my wires (existing 4-pin connector) does match in color one of the small gauge wires in the new wiring harness. So what I'm going to do is pin the new connector such that the same color wires are in contact, then accept that the other 2 wires will be of different colors.

kentompkins

Try it both ways. Just don't close up the tank hole and put the seats back because, like me, if the gauge reads low - try it the other way.

There's no chance of frying it unless you are using the two larger gauge wires (which you have already identified correctly as the power and ground for the pumps).

Trial and error in this case is your friend. For me it was correct to line up the wires by reversing the colors but since somebody routed the wires on the wrong side of the grommet and picked the wrong color wires - there's a good chance that they put the wires in randomly too.

So your setup might work with the colors in line with each other.

Good Luck.

RAT281

I know this is an old post but I wanted to know how it worked out for you since I had the same problem with my wiring. How long before the errors came up?

kentompkins

Worked out fine in the end. My problems showed up less than a minute after the car was turned on. The gauge would react after maybe 30 or 40 seconds.