car won't stay running for more than a few hours, help

[DrifterXRPS13]

hello, the car in question is an 89 s13 5spd...problem is the other day i was driving down the busiest street in town and i came to a redlight and the exhaus started pulsing and all the sudden it died....all the lights came on and i tried to start it but it won't even crank...so anyhow, i had my bro come and hit my car from the rear and pull it over to the nearest spot where it was safe to check it out....so we gave it a jump and it started right up...

drove it home, worked for about another hour and then i turned it off and tried to start it again, it cranked this time but it wouldn't turn over...next day it wouldn't even crank again...so i jumped it again and started...i thought it was the battery, so i replaced it and it worked for a day or two and then died again...another jump and started up again....

im thinking it's the alternator that's shot...but i could be wrong that's why i'm here, so if somebody could shed some light on this as i hate the gas mileage on the maxima, it's killing me, i need to drive the 4 cylinder again, help me out please!

[le_ryan]

sounds like alenator, try this, (be carefull thou) i heard if u hold a screw driver to the back of the alternator while its running, and u feel the magnetic pull, this means it still works, if not , well it doesnt, if your alternator is good , then u may have a bad ground some where, 85% of all electric probs are bad ground...

[Touchdown038]

It does sound like the alternator, but Schuck's (or Kragen or Checker) has a portable charging system tester that is free to use. I would get it tested with one of those.