Switched power source for fuel pump install
Just picking a Walbro pump because that's what Cudafever is using on his racecar.
We looked up the power needs Holley/Demon Carb stumble
Assuming this is for a carburator, its going to take minimal pressure and power. So lets say 17 amps. That's 17 amps flowing all the time the car is running.
Headlights themselves draw about 9 amps.
Tail and instrument lights draw about 3 amps
Ignition and field if original 3 to 5 amps.
Lets say only the fuel pump is on a relay. The current flow with lights on would be like this.
Compared with the current flow in the same situation with the power connected at the battery.
So even with the battery fully charged, there will be 32 amps going through the wire connection at the bulkhead.
Then 15 amps will branch off and flow through the two connections at the ammeter, the connections for the fusible link, the 16 gage fusible link, the connection at the starter relay and the one at the battery before getting to the relay.
But of course after starting, the battery is going to need recharging. So adding that, the total current through is exceed the capacity of the factory circuits.
Wiring will degrade, resistance will increase, eventually something will fail.
Yes in theory one could wait until the battery was fully recharged before turning the lights on, reducing the load some.
Also a pump that used less power would be better. I just picked one.
Regardless, an electric pump is a big load for the factory system.
This is primary reason why I suggested that when keeping the factory wiring, it is better to connect to the alternator.
Better assuming the alternator can supply the power needed at idle rpms.
If this is all too much of a project, then give the need/desire for an electric fuel pump some serious reconsideration.
Just picking a Walbro pump because that's what Cudafever is using on his racecar.
We looked up the power needs Holley/Demon Carb stumble
Assuming this is for a carburator, its going to take minimal pressure and power. So lets say 17 amps. That's 17 amps flowing all the time the car is running.
Headlights themselves draw about 9 amps.
Tail and instrument lights draw about 3 amps
Ignition and field if original 3 to 5 amps.
Lets say only the fuel pump is on a relay. The current flow with lights on would be like this.
Compared with the current flow in the same situation with the power connected at the battery.
So even with the battery fully charged, there will be 32 amps going through the wire connection at the bulkhead.
Then 15 amps will branch off and flow through the two connections at the ammeter, the connections for the fusible link, the 16 gage fusible link, the connection at the starter relay and the one at the battery before getting to the relay.
But of course after starting, the battery is going to need recharging. So adding that, the total current through is exceed the capacity of the factory circuits.
Wiring will degrade, resistance will increase, eventually something will fail.
Yes in theory one could wait until the battery was fully recharged before turning the lights on, reducing the load some.
Also a pump that used less power would be better. I just picked one.
Regardless, an electric pump is a big load for the factory system.
This is primary reason why I suggested that when keeping the factory wiring, it is better to connect to the alternator.
Better assuming the alternator can supply the power needed at idle rpms.
If this is all too much of a project, then give the need/desire for an electric fuel pump some serious reconsideration.