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Discussion Starter #1
Any idea what the aftermarket switch in pic below is for? I assume it was a mod from a PO. My best guess is that it's used in place of the in-line fuse for the fuel pump, but I don't know why. Any ideas from the wisdom of the board? Should I restore it to an in-line fuse? Thanks, as always! You all are fantastic!

Ty

IMG_8861.jpeg
 

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1973 Spider; the daily
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Not sure what car that's on but on a 73 spider they did have inline fuses. You could turn the switch off and see if you still have power to the fuel pump. You can obtain a wiring diagram from Papajam and look up the wire colors to see that way too.
 

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Isn't fuel pump wiring pink wire? That looks like it's patched into red factory wire. Could be an anti theft device, does the car start when in the off position? Must be a newer model as that looks like a barostatic pressure sensor in the background that on a Bosch plug.
 

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Discussion Starter #5
I apologize for not including critical info. It's an 84 Spider (S3). According to Papajam's wiring diagram, judging by color (maybe not the best thing to go by) and location, it looks like the switch is supplying power to both main and fuel pump relays. To be honest, I've been afraid to turn it off, but it would make sense as a cheap antitheft device. I'll go dig a little more to follow the wires more closely. Thanks!
 

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Oh for cryng out loud, just turn the **** switch off and try to start the engine and see what else does not work. Your not going to break anything. Or maybe the PO installed one of those "self destruct' gizmo they had on the old "Mission Impossible" TV show.. Owning an old Alfa is sometimes like flying without a net.. :p
 

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looks like someone got rid of the 8A fuse and put that switch in its place (judging by thick red wires)

I doubt it is an anti-theft thing, as taking the rear panel shelf out each time to switch it on/off would make it a hellova chore;)
(later spiders had a little inspection hatch)
It is probably put there by a PO who wanted to disable fuel supply whilst doing some other work on the car.

as above, just switch it off then try start her....it is quite handy being able to turn off fuel supply when doing certain jobs on a car...
I have similar, except mine is hidden under the dash so I can switch it on/off easily.

Personally I'd put a blade fuse back (or at least add a blade fuse inline with the switch)
 

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Thats were the inline fuse holder went. When the pumps got some wear on them. The 8 amp fuse would build up heat and melt the fuse holder. The cure is to use a 16 amp fuse in either the original fuse holder or put a ATO style fuse holder in its place.
 

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I would not advise doubling the fuse ampacity. Fuses are calculated to protect the wiring - too high a rating could allow too much current through the wires leading to excess heat and danger of melting/short circuits/fire.

A blade type fuse is good advice. 10 amps should be sufficient. (I don't know if there are 8 amp blade fuses.)
 

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I would not advise doubling the fuse ampacity. Fuses are calculated to protect the wiring - too high a rating could allow too much current through the wires leading to excess heat and danger of melting/short circuits/fire.
The first time I lifted the rear parcel on my 89, not only did I find what could only be described as a garbage dump of unwanted wiring and misc. broken parts, but also the pump fuse holder in a melted blob. But instead of splicing in a new fuse holder, the PO just spliced in a wire, leaving the pump wiring unprotected. I put in a blade fuse holder, needless to say.
 
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