b-seires in 99 si, alternator pulling power from battery
 

need help asap
my buddy just put a b18b1 in a 99 civic si wiring and everything else is good but the alternator is pulling the charge from battery instead of charging it.
now here is the weird thing, we put a d-series alternator on and it created a charge, but only lasts a week then it dies.
i've pulled the motor out of the car twice now and getting absolutaly sick and tired of this car now.

i will take all advise given to me and try just about anything now

thank you for looking and helping in advance

Thank you

ps: car ran good before front end crash 2 weeks ago with d-series in it

I dont mean this as an insult at all....but maybe your battery cant keep a charge?

with the d-series alternator the motor stays running WITHOUT THE BATTERY CONNECTED, IT KEEPS A CHARGE OF OVER 12V WHILE RUNNING.
BUT WITH B-SERIES IT WONT HOLD CHARGE AT ALL

Did you have to adapt a plug for the altenator?? Reverse polarity maybe??

i dont think so the plugs have to be changed because its a plug and play swap.
im thinking its the ecu, running si right now but there could be something wrong with it, so im gonna try obd2 b16 sir ecu then will see
thanks alot for the advise guys

Maybe you should go get your B series alt tested. I'll bet it will need a rebuild/replace.

well i have finally found the problem.... very stupid too......
it was the alternator fuse under the damn dash that was shorted out

glad you got it runnin !

yet another electrical problem that could have been solved if the op just checked the easy stuff first.

How can a fuse under the dash be shorted out? I can assume blown.

nothing like pulling an engine twice.....

see im not the original person who did this swap, all i was is the repair man on the swap, how the fuse blew!!! if you take the positive off the alternator and touch anything grounded when the battery is still connected it will short the fuse.
but thanks to everyone for help and advice

Wow, glad you got it

Don't take this the wrong way, but seriously.. you should not be working on cars if you do this.