Flow on fuel pump

joe_keefer · Post by **joe_keefer** » Tue Jan 04, 2011 8:16 pm

hi guys,

i`m a more than a little embarassed to ask this, but which way does the fuel flow from the pump? is the bottom the one with the fatter of the 2 nipples? and the top the end with the wires right? for some friggin reason it seems my pump is pushing the fuel back to the tank from the bottom. will the pump reverse direction if wired backwards?
i know it`s not supposed to be possible. but let me fill you in on me. murphy ain`t got nothin on me for bad luck. if something can go wrong it WILL. you may remember on christmas i was putting on my new pump and broke the spade connector off. well i drilled and tapped a hole and threaded in a #6 brass screw. it worked so well i did both sides the same. well it was such a pain in the rear to get the screws started and below freezing. i may well have wired it backwards.

thanks, joe

wkohler · Post by **wkohler** » Tue Jan 04, 2011 10:52 pm

If you wire it backwards, it reverses direction.

Just an aside:

The E34 has two brown wires for positive and negative. They're different, but only barely - negligible when soaked in fuel for 15 years (E34s have a single pump in the tank). Of course, the different sized ring terminals are the tipoff, but I had to cut the wires to install spade terminals to fit the new pump. Needless the say the car didn't start when I put it back in. Got to do the job twice with a full tank of fuel!