Seems odd that they'd fuse a fuel pump with 30Amps and feed it directly off
the battery since a a fuel pump doesn't take very much power to run. Power
delivery (ie power drop across wires, requiring fat wires) is usually not a
My old volvo was an older model and don't remember if they had direct line
going to the pump.
What is more logical is that this fuses the alternator. An alternator is
usually directly connected to the battery. It does have diodes inside that
short and cause current to flow when it shouldn't. Can you follow that wire
to see where it goes?
Also, I'd imagine that if that fat wire and fuse indeed do feed the pump
through a relay, it would most likely be connected to the contact of the
relay (the switch side) -- there's no point connecting a high current wire
to the coil (actuator side) of the relay as that is definitely low current.
That being true, the only way that you can have any appreciable current
running is if the pump is running, even with the car shut off. That relay
must be driven somehow.
I'd still first check to make sure that that fat wire/fuse is not connected
to the alternator, though..
Just one more thought:
We know a car can't drive without a fuel pump but can drive without an
alternator (albeit not very long), right?
Disconnect that offending fuse and see if the car starts and runs. If it
does, that fuse was clearly not to the fuel pump.
Hope you find it soon. Let us know how you make out -- it might be OT but
now I am interested. :)
Nope - the fuse is for the fuel pumps. There is a small in-tank impeller
pump that draws a little under an amp and a main pump under the car below
the driver's seat that typically draws a bit under 10 amps... probably more
on startup. Both are controlled by separate sections of the fuel pump relay.
The in-tank pump is on any time the ignition is on, while the main pump is
The alternator is not fused.
Yeah, Volvos are quirky cars -- I had a 1972 145E, I guess their first
entry in the fuel injected market. Have worked on some DLs friends
owned. Built like a tank, that much is sure.
I've owned two 900 Saabs (the other Swede) as well -- talk about
quirky!! They are great fun to drive but do have some not so
straightforward issues when it comes to repair.
Hope you got it resolved?
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