Re-reading your original post, behind the spare tyre is the blower fan for the heater/AC..... Is your climate control on? Maybe it's the blower motor making the noise, or the climate control unit having a bit of a freak out if the unit has been affected by leaking capacitors internally.....
Reading your reply, we're back at the ALB pump.....
aka Jonathan!!
'92 charlotte green auto.... as a daily
'37 Ford Y street rod......... something for the weekend!
...... if a photobucket pic is foggy, click it, and it'll take you to the clear version, yes, it's a clicking faff....