I'm elbow deep in the electrical system of my pickup swapping in EFI. I'm using the fuse box from a 94 f150 for a relay/auxiliary power box and have plenty of extra fuse slots I could use to replace all the fuse links. Is there any reason not to, and if not, what size fuse would replace which size fuse link?

 

The 94 f150 fuse box is also fed power from a fuse link at the starter relay.
Also the 94 f150 alternator power is fed to the battery and other systems through a fuse link at the starter relay.

The 94 f150 engine compartment fuse box already has a fuse in it for the fuel and other system that had fuse links in previous years that are not covered in the first paragraph above.

 

Thanks, now let me muddy the water with more details:

I'm probably going to do a 3g alternator swap as well. From what I've seen, I'll be needing a ~100amp "superfuse" between the alternator power out and starter solenoid/battery connection post. That replaces the fuse link, correct?

The 94 f150 fuse box is now completely empty - I yanked all the terminals and can wire it any way I want. It's going to be a standalone relay/power block for the EEC. I cut the metal plate that distributes battery power more or less in half - ~8 fuse slots box will get power from the battery and ~6 will be powered by the EEC relay when the ignition is in run to switch on the other relays.

The wiring diagram shows fuse links on the power to the EEC and Fuel Pump relays. No worries replacing them with fuses, right? Two other relays (ignition, MAF & HEGO) will get power from 15 amp fuses off the battery connection; the A/C WOT relay gets power from the A/C pressure switch.

Anyway, I've got plenty of room to take anything else that currently has a fuse link and run it off a fuse in the box if it's worth doing.

 

Not sure what amp alternator you are talking about but for a 95 amp alternator I would use a Gray 12GA fuse link. Ford puts a 300 Amp fuse with the 215 Amp alternator so 100amp seems a little small.
The 130 amp alternator uses two Gray 12GA fuse links in parallel.

 

What are fusible links? They are safety devices that protect the large main circuits of the wiring. So to replace them with fuses, you will have to use very large maxi fuses. You will also notice that they are located near the power distribution area at and after the starter relay where power originates from the battery. So any fuse replacements need to be near the battery/starter area.

Is there anything wrong with fusible links? No. They never give any trouble and never need replacing unless something unusual happens, and that's usually caused by us, the owners. That would be a serious accident, replacing the alternator or other various jobs without disconnecting the battery, and modifying the wiring without proper protection for the wire.

So if you do a good job on your wiring and don't overload the circuits, your fusible links will sit there forever and never give any trouble.

 

You can use the blade fuses, but, you might be better off with a relay instead. The reason being is you can subject a 10 amp fuse to a 11 amp load and it might not blow, even though the wiring after it is melting, until it contacts ground. Fuses are designed to accept short term spikes.

One the other hand, the fusible link would probably overheat and blow before the wiring after it melted, if it is sized smaller.

Putting a resettable thermal relay in is probably the best of both worlds.

 

The no. 1 reason not to use a resettable thermal relay is it introduces another point of failure into the systems.



Look at the location of the link: at places which is exposed to heat, thermal, and vibration.

Put a resettable thermal fuse there, and you have complicated moving parts that is exposed to a harsh environment.


The other reason to not use a Maxifuse in the box is it means more wiring, more connections.

Sometimes, a simple (and nearly trouble free) link does the job.