AHHHHH electrical help needed, at wits end!!!

[BassAssasin71]

ok, so here is the story....daughter runs truck (72 f100) out of fuel...no biggie, run some out try and get it started.... kill battery in process....no biggie have another at home.... put battery in, black to negative...red to posi.....POOOOFFFF. Big mushroom cloud at positive side of solenoid. lots of sparks and sheared off connectors. once realizing what had happened (idiots before me put wrong color cables on) start replacing parts. solenoid and new battery cables first up. start reconnecting wires. problem is there was a fusible lnk in this system. replace it with a 30 amp blade style in-line fuse, wire everything back up, as soon as key is turned on, fuse blows..... figure out wire that is causing (i am no wiring expert) and I disconnect. As soon as I disconnect, everything runs perfect. New problem, next day, trucks battery dead. ok, check alternator...its bad...ok replace alt....still not charging...ok, replace voltage regulator.....still no charge. Find wiring diagram (thanks FORDification for that) start tedious job of tracing wires.....find wire that is supposed to run from VR in line with fusible link back to positive side of solenoid....... tape it all up, cross fingers, jump start truck, take off cables and check voltage across terminals.....13.7 SWEEEETTTTT. hand daughter a $20...go put gas in. truck has now started up 4 times. Phone call....hey dad....truck wont start...got nothing not even headlights.........AAAGGGGGHHHHHH. go check truck....30 amp fuse blown.....this is where I need the help....I AM TOTALLY lost now. why am i blowing fuses? why did it start 4 times and then blow a fuse? any help would be appreciated....sorry this is such a long post, just wasnted to make sure you have all information. by the way, it is a 72 f-100 with a 390, non a/c if that matters

[fordman]

where is this new fuse at? what does it go to and run from?

[BassAssasin71]

it goes from the positive side of the solenoid to the alternator. I just cut the fusible link and in its place put the fuse

[fordman]

that black wire? it tees into the wire that goes between the alt and the regulator also. is that how yours is?

[BassAssasin71]

yes, exactly

[fordman]

here is something i am thinking but i dont really know. but maybe 30 amp isnt enough fuse. i have no idea what the fuseble link is suppose to carry.

[BassAssasin71]

well that came to my mind as well..... where could I find out what the rating should be.....

[fordman]

idk for sure. would it be true that if the alt puts out a certain amount of amps say 55 or 65. that the fuse would need to match that?

[Fordnication]

the fuse should be less then the max amps of the componet (i.e. starter, relay, light bulb) is rated for.
For example if the starter is rated @ 15 amps the fuse should be 14 amps no mre then 15 for sure because
you'll risk damage to the componet.
Tha ALT. is your main power souce there for the current flow is going out, check the amp rating on the item after the fuse in question.

[Miztirelliz]

hey guys i dont think a fuse is supposed to be in that location

[knightfire83]

If your going to run a fuse in that location it should be a maxi fuse not the standard small blade type fuse. Maxi looks like a standard blade fuse on steroids, they can pass allot more current than its counterpart. However a replacement fuseable link will be the correct way to fix this. Most likely the link will cost less than a socket and a maxi fuse.

According to the wiring diagram on this site it originally was running a 16 gauge fuseable link to protect the 10 gauge output wire of the alternator.

A fuse blowing between the VR and the Solenoid should not cause the headlights and the rest of the truck to loose power. The rest of the truck draws power from a wire also connected to the solenoid. Sounds like there is other problems besides the charging circuit.

Test running the truck while disconnecting the battery isn't a good idea. In this particular scenario your running the entire truck's power requirements thru your little 30 amp fuse, (except the starter) and that ante likely to last very long without blowing.

To start I would:
1. Replace the fuse with the correct fuseable link
2. Double check the connections at the battery and solenoid.
3. Check the wire that runs the rest of the truck, it too has a fuseable link coming right off the solenoid terminal.

Here is a little info about fuseable links I found on the net: http://www.alanhorvath.com/54chevy/fusible_links.php According to this the fuseable link ideally should be a 14 gauge wire, which is 2 gauges bigger than what Ford originally used on our trucks. However with the location in the charging circuit I'm not going to second guess the Ford design.

Hope this helps.

[oldyeller69]

you have to have a fuse that is a little higher than the alt otherwise it will blow. the other thing is you do not take the cables off while the truck is running it throws a big power surge through the system and fries things always test the charging system with the cables hooked up and running at the battery and at the battery terminal of the alternator then turn on all the accessories and check again, the voltage should go up.

[Mancar1]

I was reading away when I realized the 09 date on this post.

[tac]

Did you use a standard 30 amp fuse or the FUSE link replacement fuses? A fuse is not a fuse. Fuse links will handle surges like a "slow blow" fuse. Bussman makes an FL series for to replace fuseable links and can be found at most autoparts stores. Summit also has them. http://www.summitracing.com/search/bran ... toview=SKU

[Calfdemon]

Talk about resurrecting a thread from the dead... Yeah, I was falling victim to reading all of that too, but then when I saw that Fordman was the main respondent, I took a look at the date as I figured it had to be old.