Fuel pump kill switch wiring, correct location? 1989

[Jaxx]

I am looking for a way to disable the fuel pump, not that it would stop any serious thieves but it would at least stop kid joyriders with flatbladed screwdrivers.

I once owned a fiat that the PO had wired in a ignition switch, even I could see how to bypass that, however I did once come back to find it with a broken window and the dashboard ripped to shreds so it obviously worked that one time as they didn't trace the wiring far down enough. I am thinking that a pump switch under the rear seat would be less obvious.

So am I right in thinking on a 1989 and later this lead with the round white connector ends inside the fuel tank with the pump as the plug pictured in the bentley manual? (disconnected in the picture)

Also would a 20A, 12V aircraft toggle switch be good enough to splice in there, as far as the wiring diagram shows the fuel delivery circuit is on a 15A fuse.




This is the internal fuel tank connector as shown underneath the largest access panel, I assume the transfer pump is inside the smaller circular access panel.







and this lead with large white connector is what I assume must be the power lead coming from the relay all the way down the sill and entering the tank.




Thanks for any help or advice.


1989 320i

[StereoInstaller1]

Yeah, you seem to have figured it out...but why bother? Just get an alarm! Easy install, like 4 hours or so, then you have keyless entry too.

[jlevie]

The round white connector is for the wheel speed sensor on that quarter.

It would be easier to insert your switch in the wiring to the socket for the fuel pump relay in the engine bay. But I think a better choice would the insert a switch in the small wire that runs from the positive battery cable forward. It powers the DME, coil, pumps, etc.

[Dave]

^^^^^^^

What he said.

And I'd also note that in your 1989, there is only one pump - and it is under that larger access panel you have pictured. Under the round one on the driver side is a level sender.

[Lurker27]

These guys have it covered. I spliced my new fuel pump wire at the pump connector and at the relay. In the bundle along the door sill its gonna be tough to find the correct wire.

Also, nominal amp draw is 10A - You'll be fine with that switch.

[Jaxx]

Ok thanks guys, I pulled the cover and some trial and error reveled its the green and purple wire on the harness, I will post something up after I get the switch fitted.