[alfa] fuel pump electrical help

["John Y. Hung" <jdaezhung@xxxxxxx>]

Dear Dan,

I just traced the fuel pump electrical lines on my '88 Spider Veloce. 
Your car may be similar. I hope this description helps. Sorry for the 
length, but the electrical line is long also!

Starting behind the passenger seat, the main fuel pump line comes into 
the car interior through the floor pan, behind the  computers. The line 
runs next to the computer, under the carpet, along the floor pan behind 
the seats, over the driveshaft tunnel, and then to the driver side. In 
the corner below the trunk and fuel door release handles, the in-tank 
fuel pump line joins the harness, but the two lines are still separate. 
Together, the lines run in the harness alongside the driver side floor 
channel, and then turn up at the firewall. There is a big connector up 
there, deep in the front left corner. At this connector, the two lines 
are crimped together into a male pin inside the connector. Both lines 
are pink with a white stripe.  (My fuel pump woes were at this 
connector - I had an intermittent open circuit, which prevented the 
pumps from getting voltage at inconvenient times. I squeezed down the 
female socket and spread the male pin, and things are now perfect for 
me.)  Anyway, from the other side of the connector is a line (same 
color) that runs up and then forward through the firewall. Once inside 
the engine compartment, the line runs in a harness across the firewall, 
past the hood release mechanism, and then comes out next to the 
windshield washer bottle. At this point, there is a spade connector, 
and the color of the line changes to white with red stripe. I suspect 
there used to be some kind of safety device that has been taken out.  
The new white/red line runs back into a harness that passes back 
through the firewall on the passenger side. Inside the interior again, 
the harness turns down to the floor, and runs along the passenger side 
floor channel. The white/red line comes out of the harness and goes to 
... THE FUEL PUMP RELAY! The fuel pump relay is the taller of the two 
relays back there; the main relay is cube-shaped.  On my car, the 
white/red line is crimped to two orange/black lines at the relay socket.

In summary, current for the main pump runs from the relay, and makes 
about a 15-18 foot trip around the car before coming back within 6 
inches of where the line passes through the floor pan! Current for the 
in-tank pump makes just as long a trip, but passes through the back 
wall on the driver side before going to the fuel sender/pump assembly.  
The lines are not particularly heavy, and I suspect the voltage drop 
along the line is not negligible.  If the voltage drop is significant, 
the motor will run slow, and the time period of heavy startup current 
draw will increase.

In the future, I may bypass the long line, and splice a jumper between 
the white/red line (at the pump relay) and main pump line (in the area 
behind the computers).  I have read that some cars have had this 
modification done at dealers - anybody else seen this?

My recommendation is to find the connector in the vicinity of the 
windshield washer bottle. Open up that connector and the connector on 
the driver side firewall (disconnects the fuel pumps). Now check for 
shorts to chassis: a) between driver side connector and spade 
connector, and b) between spade connector and fuel pump relay.

Best wishes,

John Hung
Auburn, AL
'88 Spider Veloce
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