2G 100amp alternator fuse keeps blowing

[boostmaster123]

Alright well i have been having some alternator issues and i cant quite figure them out. first off i have been through 3 auto zone alternators and now i just put in a new stock one. after i put it in my car ran kinda funny at idle and so i looked in the engine to see if anything looked out of place and i saw that the 100 amp fuse was blown. so i went out to the parts store and bought a new one and tried the following:
1. disconnect the negative..put in the fuse and re connect the negative and it would spark...blow the fuse.
2. disconnect the positive...put in fuse and reconnect the positive..big spark..blown fuse.
3. leave the battery connected and put fuse in...fuse sparks

i cant figure out what is going on...is there something really obvious that im not seeing with the process of replacing the new fuse.
am i just not disconnecting the right wires or something because every one i talked to said that it shouldnt spark that much when you put it back on.

please help i need to figure this out soon

 

[TheCrazyDSM'r]

check over all the wires by around the alternator make sure none of them are grounding out anywhere. That may be the problem.

 

[boostmaster123]

alright well i brought it to my local mechanic to check things out and he told me that after taking the alternator out and testing it that the diodes are fried. can anyone confirm that this is something that could cause my problem?

 

[laserblue]

Yes, of course a dead short [such as toasted diodes] would cause a 100 amp fuse to blow. Hell a 10000 amp fuse will blow with a dead short!
Did the other alternators suffer from the same problem? If there is a huge current drain [like from a short somewhere in the wiring] I guess that any alternator will not deal with the strain and those diodes may give up.... but you said that the car DOES run... so I don't know if anything is wrong... other than an amazing amount of bad luck.
Give me more info about what's going on, and when it started, and what you did, and what new gizmos you installed before the problems happened, etc.
Thanks!!!!!!!!

 

[boostmaster123]

well the first alternator i had was an oem alternator and that one went becausee of a bad voltage regualtor. then i bought one from auto zone and that one went because of a bad bearing. then i got two other autozone alternators and those went because of bad voltage regulators and now i got the last one from a salvage yard. since i bought the car the only electrical stuff i added was: gauges, gauge faces, EBC, and a turbo timer, but those things dont really draw alot of power. the mechanic said that he looked at all the wires and there wasnt anything he could see that was wrong with them, and since some of the alternators have gone for different reasons he thinks that im just getting crappy alternators. do you know anywhere that carrys good remanufactured alternators? i hear that oem is the best
thanks for your help..i appreciate it

 

[t90tsi]

im having alternator problems as well, i took out my new one from orielys and replaced it with a spare stock one my friend had for now. im going to take it back because the voltage regulator was bad and was overcharging my system, fuel pump sounded like it was going to explode and headlights got really bright every now and then. i ordered a mitsu alternator from conicelli online, they sell factory direct parts. i think the 75 amp mitsu alternator cost around $170. should be in pretty soon. their website is www.partznet.com
check it out ive heard good things about them. hope this helps

 

[boostmaster123]

wow...170 for a stock alternator..thats really good. they go for 450 at my local mitsu dealer. thanks for the reply ill check it out