1990 Charging problem

[Dkferguson]

hello new to the forums here have a 1990 240sx s13 with a ka24e great little engine built her up from old ones anyway long story short

i keep loosing power and battery 3 days into driving it or when i have my massive sub hooked up

took it the Nissan mech and he said it's the alternator well since i had another alternator i went ahead and swapped it out car started ran fine did it again thought it was the battery got a new battery have replaced the battery twice since then and its still only running about 3 days or less had alternator and battery tested computer says they're fine well obvio0usly it's not fine cause it keeps eating all my battery power please help diagnose sorry for the no grammar

thanks concerned nissan owner

ps how can i check the 75 amp fuse for the alternator

[S13Joe]

Fuse box under the hood on the passenger side. Take the fuse labeled 75A and look at the top of it. You can see a little piece of metal in there, if its broken in half the fuse is blown.

[Vegascorbin]

After checking the fuses and being sure they are ok is to disconnect the "massive sub" and check the voltage at the battery. Should be about 14 volts with the engine running. Then connect the "massive sub" and check the voltage. if it is not still above 13.5 volts with the engine running then the Altinator just can not put out enough power for both the engien and sub.

Check that and let us know what you find.

[Dkferguson]

thanks guys checking voltage as we speak it's not that massive it's just 2 12 inch pioneers in a ported box but i am checking also i wasn't clear on the fuse i was talking about i was talking about the plastic topped not clear one i already replaced the clear topped ones big gray multiple prongs says nissan on the top of it

[KA24M90]

You can upgrade the Alternator from a 97 Quest and pick up a few extra amps to help out the "super woofer" you got. I did it and noticed a difference in the dash lights not flickering when the sub hits. The factory Ka24e alt puts out 80 amps if I remember right and the Quest has 105 amps. Not a big difference but it helps with extra electronics. The only catch is that the lower ear on the Alternator has to be rounded out because its threaded on the Quest Alt and not the 240 Alt. And you have to shave almost 1/4 of an inch off of the top ear's back side to get the alternator's pulley parallel with the rest. It takes about two hours to get everything right but it was worth it in the end. To me anyways.

[Dkferguson]

hey got it amps checked without sub it's low power 11 with the car running. I do have one idea wanted to run it by you guys, well 2 actually this was an engine swap and i simply deleted the ac taking out the pump and pulley and all there are a few wires left that i don't know what they are for. And at one time i was shocked by them so i taped them up there's a ground and a few plug i am simply lost by it i know they are live. would tehy have anything to do with my issue also, I only have the one bolt going through the bottom of the alt to attach it to the block i have the bracket that goes on the top to make it more stable does that really have any effect on how well the alt will run i mean i have taken it out alt have it tested it test good starts drives fine then i turn on my lights or amp and it dies pretty quickly does it sound like a drain to you guys or a alt problem i have taken the dang thing out so many times now i just want to be sure i was stranded last night for an hour while my buddy charged my battery back so we could get back to town

i am definitely not paying someone to figure this out i did the whole engine swap myself i should be able to with a little help from you guys narrow this down

thanks Angry s13

[Dkferguson]

so onward with this ridiculous saga

finally discovered it was the hack job i call wiring under my hood that was the culprit alt ran fine and charged when in shop but from alt to box then battery there was an issue so i ran a 6 gauge jumper wire from power wire to along with the old one never took that off battery and all was fine drove around like a mad man for 24 hours or so loved every minute of having a full power guess the little alt didn't like it though charged to much

and now the alternator is officially gone bad no worries i have another could i in theory run that wire again with a fuse this time the equivalent of the 75amp that is originally running from box to battery because i don't see any other way till i can tear apart the fuse panel and play with the wiring which is going to be a pain so i trying to get by with this is my only car as one these days

my maxima bit it and i have children and a wife that needs to work at lest 20 mins away everyday trying to make this work i know it's not the way it should be done but with a fuse would that stop it from frying the alternator

thanks again guys also withe the alternate power wire i ran everything was running 13-15 like it's supposed to but i ran my subs and everything else at that point so overpowered the little alt i am assuming any quick ideas or diy fixes you guys have ill try also something must have happened because now i have very little backpreassue and it sounds like my car is farting go figure on

that one figured must be cat related cause it sounds like it's right under my seat and loud and ugly sound any insight let me know thanks all

pissed off nissan owner