Fuel Pump Whine

[SuspiciousPizza]

I currently have my GL all torn apart to address some well entrenched gremlins.

The main issue I have a question regarding is why does my fuel pump bog and whine when I use my turn signals?

Fuel pump operates as it should (although I don't have a fuel pressure gauge hooked up at the moment, I will be adding several gauge pods, including a fuel pressure gauge, once I get the engine back in my car.)

However, whenever I used my turn signals my fuel pump would whine a different tone only when the turn signals blinked. Between blinks it would have a normal tone.

The negative terminal arcs when I plug in the battery, indicating a short (?)

Obviously I'd assume it's a wiring or ground issue (almost all the grounds in the engine bay were caked in oil, grease, and dirt but I've been thoroughly cleaning the engine bay with Simple Green and a multi-pack of tooth brushes while I have the space to do so.)

Would anyone have any pointers? Would I be able to use the fuse box to check which circuit is shorting? I can read a multimeter, have a very basic understanding of circuitry and have a full set of service manuals at my disposal.

 

Thanks!

:]

[el_freddo]

An aftermarket head unit will always create a tiny spark when connecting the battery. 

Other than that the fuel pump issue is either a poorly operating alternator, old wiring with resistance points or a battery that isn’t coping as well as it used to. Lastly could be some sketchy wiring done by a pervious owner. 

You’d really need to check out if anything was modified before your ownership. Eg: I have a Gen1 RS turbo Liberty (Legacy over your way) that someone used the door switch circuit as the earth for the aftermarket head unit. Whenever someone opens a door the headunit turns off as the circuit becomes active. Classic (*facepalm*). 

Cheers 

Bennie

[SuspiciousPizza]

I do have an aftermarket radio, and it's an absolute rat nest underneath the steering column and behind the glovebox. I figured this was a good candidate to begin diagnostics. There is plenty of wire nuts, misc wire gauges, and "good enough" wiring *facepalm* indeed.

Would anyone have a wiring diagram for an '89 radio? I don't even know which model of radio came with the car from factory, let alone the wiring. 

Alternator does seem to be pushed pretty close to its capacity, but I'm not convinced it's the alternator. Voltage drop during turn signal flashes is 2-4 volts according to the volt meter in the gauge cluster, a big drop. Alternator is a Nissan Maxima VG30E alternator mod. Pretty commonplace.

:]