[youngmechanic]

I'm new to electrical stuff and I came here to find help and answers. my fuel pump died on me so I replaced it and now there is no power going to the fuel pump. The car is a 1948 Chevy with a 396 big block in it. thanks in advance

 

[vicrod]

old pump bad?

With a test light check if the fuse is blown.
Also make sure the pump is grounded.
Sometimes safety switches are installed like an oil pressure switch. This is a common GM practice.

vicrod

 

[EOD Guy]

Vic is spot on..... Start at the fuel pump fuse, then the fuel pump relay (if equipped), then the oil pressure switch.

Should be three wires, depending on the switch, on the oil press switch......
common (C) which should go to the fuel pump
normally closed (NC) which should go to the small terminal on the starter or the starter wire
normally open (NO) which should go to a "hot in run" pwr source

When the vehicle is not running the oil pressure switch has no pressure and the switch connects the common and the normally closed terminals...... so the small terminal on the starter and the fuel pump.

When you turn the key to start, the power from the sm terminal on the starter flows thru the oil press sw to the fuel pump etc..... After the engine starts, the oil pressure sw develops press and disconnects the NC terminal and connects the NO (which is pwr'd by the "hot in run" source) which now supplies power to the fuel pump etc.......

 

[EOD Guy]

click this link

http://www.hotrodders.com/forum/92-s10-wiring-gauges-395138-2.html#post3311450

there is a diagram I posted (post #20) that shows a oil safety switch etc... The wire labeled "your dia Grey" is the one that goes to a switched 12v pwr source, I drew that diagram for his application specificly, but it might help you understand better.

 

[youngmechanic]

cause the battery to drain

With a test light check if the fuse is blown.
Also make sure the pump is grounded.
Sometimes safety switches are installed like an oil pressure switch. This is a common GM practice.

vicrod

would this also cause the battery to be drained?

 

[vicrod]

If the fuel pump is not wired correctly it could be running when everything is off thus causing the battery to drain.
Check out EOD's excellent diagrams and verify that the pump is wired correctly.
We can walk you thru this but be prepared to find the components he called out.

Oil pressure safety switch.
Relay.
Starting prime circuit.
Ignition ON connection.

vicrod