funny behavior on FUEL- speedpro pin

[JeffB]

I've been running a fasttrack harness that had the factory computer controlling the factory fuel pump... i just put a new fuel system on and i switched over to having the speedpro control the relay... i've got the + side of the relay tied directly to the battery and the - side connected to the speedpro... the problem is that when i turn the key off the the pump runs for a second and sometimes even after i pull the key out it will go click-click-click-click real quick... then it seems to be done... i'm 99.999% sure the connections are correct and the wiring is intact... i'm wondering if this is normal behavior for the speedpro? perhaps it momentarily grounds its pins during shutdown or something? my main concern is that this is somehow random and that my fuel pump could just turn on in the middle of the night... i know i could always wire the + side to ignition and not battery but i thought i'd ask about this first...

thanks,
jeff

 

[Lance]

The fuel pump drive is technically an open collector darlington drive. If the ECU is unpowered, the output should be hi-z. Unless there's a problem with the ECU, the fuel pump relay should never be activated by an unpowered ECU.

Lance