I'm going to use this diagram to wire in a new to the car fuel pump but I'm not sure what size of fuses to use.

I would appreciate recomendations from those who have a handle on the theory, I'm a practical guy.

Thanks,

Chris

The factory fuse is 20 amps (in the 73 at least). The fuse size really needs to be sized for the wire used as the fuse protects the wire from cathching fire if an overload should occur. What size wire are you using?

Also, you should place the fuse on the battery side of the relay.

Edited April 3, 201311 yr by beermanpete

To elaborate further on what Pete wrote, you should put a fuse between the solenoid and the oil pressure switch, as well. You put the fuse as close as you can to the positive side of the battery to protect as much wire as possible, since the chassis is grounded on the negative.

The documentation should specify the number of amps it draws. Just up-rate a bit from there, to the next fuse size (maybe leaving 50% overhead). As others have said, make sure your wiring is suitable for that ampacity. Standards and conventions vary widely, but your fuel pump circuit should be as safe as anything else in the car if you find another circuit with your chosen ampacity and duplicate the wire gauge used there.

I'm using the existing green wire that is in the wiring harness, I'm pretty sure it's 14ga, the in line fuel pump is the RX7 unit that seems to be a popular replacement for our cars. So I guess a 20 amp fuse should do the job.

Thanks a bunch,

Chris

I would drop that down to 10A. The pump shouldn't draw that much to start.

  grannyknot said:

[ATTACH=CONFIG]62205[/ATTACH]

Still waiting for the oil pressure switch to arrive in the mail but have started routing wires.

The existing ignition wire, the original one, that that triggers the starter solinoid

does it just get disconnected from the solinoid as the soliniod is now going to be triggered by the OPS which is being powered by a different ignition wire?

Hope that makes sense,

Chris