voltage drop help

[mattp1788]

ok i have a 79 CJ7 with AMC 258 i6 / 4.2l howell FI and hei didtributor upgrade. I just replaced the altenator because my voltage was dropping and thought it was bad. still now after the new altenator my voltage drops down so much while i am driving the jeep that when i shut the motor off i cant start the jeep. I went and had the battery tested and they said that the battery was good. I checked the voltage before starting the motor and it was at 12.6 volts and after i start it and is running it stays the same I thought that with the altenator charging the battery it would be higher? Did I just get a bad altenator or what was else would make my voltage drop and not keep my battery charged?

 

[Barry2]

Have them check the alternator and if is good start looking at the wiring.

 

[Torxhead]

The voltage while running should be around 14.5 volts. The later CJs had a 78 amp alternator as an option, you should have got one of those or a larger alternator upgrade. I am not sure how much juice the electric fuel takes but that could be the problem if you are only using the 40 amp alternator. Running a ground wire to the alternator housing can help also. The voltage at the electric fuel pump should be within .5 volts of the charging voltage per Howell instructions.