The tan wire should be plus 12 volts and should go to the red wire inside of the tank that goes to the pump plus
the black wire is the ground wire that goes to the sending unit (soldered to the top of the unit). Inside it goes to pump negative so it ends up serving as ground for both the float and the pump.
The third wire is either pink or purple....it goes to the resistor in the sending unit/float.
I am not sure how you reversed the pump because the connector that you disconnected from the old pump should simply pop into the connector on the new pump and should only go one way.
I know it fits both the walbros and the deatschwerk pumps.
I am guessing that when you reversed the wires you are now feeding power into the sending unit ....I would have thought that would have gone to ground and popped a fuse...but, I never tried it...maybe the pump is using enuf power to minimize the power going to ground thru the resistor of the sending unit?
?
If you did not change any wiring inside the tank, it almost sounds like you have a pump that was wired backwards at the factory.
I just looked at the walbro I pulled out the other day and it is marked Plus and Minus on the top of the pump by the connector...th
ink you are going to have to drop the tank and look at the pump and see if the red wire is going to plus and the black to the minus...and the red wire is going to the tan wire ultimately
I don't think this will help much in this case
http://www.vortexbuicks-etc.com/fuel_pump.htm
