Thread: Fuel pump running with key off

Well something is turning on the relay. Did it ever work correctly?

If the Casper has its own relay is it positive or negative triggered?

I'm not familiar with the rewire as I have always done my own since the amps are already back there so there's power. Then I use the stock fuel pump wire to turn on the "Hotwire" rewire. If you replaced the relay I'm assuming you meant the one in the fuse box. If so you will need a meter to check terminals 85 and 86 for power. You should have +12v on one and the other should be switched common (-12V) that is the turn on and off for the relay. If you turn the key on it should prime and go off after 2-3 seconds. If you don't get it to turn off the wire from the PCM may be shorted to ground. Check the harness that runs from the fuse box to the PCM it can get cut from the belt if the loom is loose.

It still ran without the relay installed?

So what triggers the relay on the kit? Is it possible for you to draw up a little schematic as there are at least a dozen ways to skin this cat when it comes to how to power the pump.

It would seem to me that you would use the factory fuel pump relay to turn on the kit relay. You could also just have it connected to an ignition hot (not recommended), you could even have it on a switch, in a ditch with a witch.... but I digress. There's a lot of ways to do it.

Jeff

It sounds like the Casper's relay is bad and is sticking in the closed position. As it says in the instructions the factory fuel pump relay turns on the Casper's relay. Why it shut off when you shifted into Neutral is beyond me, and seems like it would just be coincidence. Ask yourself this: If you removed the fuel pump relay that turns on the Casper's relay how could the relay stay on? The only logical answer is either the relay is stuck closed (which happens occasionally) or or there is something going on with the wiring. I know for a fact that the factory relay's coil gets +12V from the ignition and that the other side of the coil is driven from the PCM. The relay sends 12V to the fuel pump. When you use this rewire, you are using the 12V that would normally turn on the pump to turn on the relay in the rewire. so at this point it would seem to me to be a bad relay. There may be other factors involved, but you have not made me aware of them.

Jeff

Yup, but I work in Houston.

It sure seems to be a wiring issue, though I am not sure why putting it in Neutral would have any effect on shutting it off, unless there is some kind of feedback that is just enough to activate the relay in the rear. It may be a chaffed wire or something. Like I said I have always run fuel pumps off of my amp wiring since it's already back there. On 4X4's I usually have a main power wire to run for fans and such so I typically use that as well, plus I'm running all the wires anyway. This system I am not familiar with, but basically you should have a heavy gauge wire with a fuse near the front, a trigger wire for the relay. (I usually use a negative, but they are using positive from what I can tell), and a wire leading to the pump. The way I run something like that is:

87+86 B+
30 to pump
85 to switched ground.

The other way to run it is:
87 to B+
30 to Pump
85 to ground
86 to switched positive (for turn on)

Numbers refer to what they do on the relay.

Bring it over and I'll fix it. May be easier to bring it to the shop... I have AC here. I grew up in Conroe, and Porter isn't that far from Conroe down 1314.

Jeff