I just finished installing my electric fan in the Mav. Currently I have it wired to a toggle switch since the car is a weekend cruiser it seemed easy and I just finished removing wires from the engine bay I am not in a hurry to add any! My question is this.. My fuel pump is also wired to a toggle switch but it is hot-wired. Meaning there is no fuse or relay between the pump and the switch. If I wanted to add a fuse to that source what size and where do I wire it to? Also, my fan came with a 30amp fuse that I have not wired in yet. The diagram shows it wired between the fan and the ground. Sound right? Thanks for the responses, electrical and body work are about the only 2 things that I stress over doing myself.
yea im really not an electrical guy either but i alwayse thought the fuse went in the hot wire between the power source and whatever your running? i can swap a engine in a few hours but the last and only time i ever did a radio it took me a whole week lol
Doesn't matter where the fuse goes it will still stop the current if the circuit opens. (that doesn't mean there is not a reason it's better in one place or the other)
You want the fuse (circut breaker) as close to the power source as possible! It protects any short! (bare wire, overload, ground cross) Always best to run seperate circuts for each unit. 1 for pump, 1 =fan, 1 = any other acc. Just think as 12 volts as a water line. Run a water line to each faucet! If you like your car an don't want Smokey the Bear to take it from you, fuse every line off of batt, power stud or source! This is a very safe must to keep car from burning or melting!
And the size of the fuse should be? Also, my one wire alternator runs straight to the battery. Fuse it ?
25-30 amp for fuel pump 20 amp should do for fan. If they kick or blow go up 5 amps at a time. Above 30 amp, you have a problem. Alternator doesn't get fused
Thanks. New project for the weekend! I may just install a small fuse box in the trunk (batteries there) to keep the engine bay free of any more wires. Thnaks again for the help. Scott
Sounds good on the trunk! The fuel pump should be mounted close to gas supply. Also, you can run 10-12 gauge wire from batt to a relay- relay to pump an run 14-16 gauge from relay to toggle. Didn't talk on this but relays cut out power loss an running lots of big wire.
Rule of thumb for fuses is they should be rated 25% higher than your load, so for your 20 amp pump a 25 amp fuse should work. If the device has a high surge at start up you may need to use a slow-blow. For fans and pumps I like to use circuit breakers so you don't get stranded. Make sure your wire is the proper AWG, too. As for the wire from the alternator to the battery, use a fusible link or make your own from a piece of copper wire that is two sizes smaller than the gauge you need to carry max alternator output current. As mentioned above, any current opening safety device should be located close to the power source. If your fan motor or power wire develops a short circuit to ground, a fuse in the ground lead won't disconnect power from the fan or wire. Then you'll let all of that magic smoke out of the wires, things don't work right after you let out the magic smoke.
To know what fuse to put on the pump, you need to know how many amps it is rated for... It was mentioned to fuse it 25% over that. Sounds about right. Just to pull a number out of the air is not good. 20 or 30 amp for the fuel pump, as previously suggested, is doing just that. Seems to me a fuel pump might only pull 10A, for example. In which case you would want 12.5A protection if you add 25%. Now, I doubt they make that fuse... but they do make a 15A, and 12A might not even be uncommon... Gotta look. The fan will probably pull much more than the FP, but again, you gotta check the amp rating of the Fan. As mentioned, the fuse will work in theory when placed in the ground. However, IMO the ground being all around and relatively unrestrained, the positive wire is the one sure side that is contained and should be fused. For example, you fuse the ground wire, but the fan housing is grounded through some mounting bolts. If you don't realize that, the fuse may burn at the wire, but the bolts are not fused... So the protection is nullified. In the case of the positive wire, there is only one and it is contained. So if the fuse blows on the hot wire, there are no alternative routes for power to travel and defeat the purpose.
