305 running rough

[Schurkey]

Do I need to take the cable off the alternator to check? I checked with cable on the alternator and had 12 volts

12 volts of AC? Far too much. I don't think that's even possible. 12 volts of DC is too little. DC voltage should be more like 14.

RUN THE ENGINE WITH ALL CABLES CONNECTED. Set voltmeter to AC volts, and connect to the alternator output stud, and alternator ground. Measure AC voltage (often called "ripple" when talking about automotive alternators.)

Shut off engine. Charge battery with alternator + cable disconnected. When battery is FULLY CHARGED (Measures 12.6--12.7 volts DC after surface charge has been removed. (Will measure ~13 volts or more with the surface charge) see how long the battery remains at ~12.6 volts DC with the alternator + cable removed.

If the battery stays fully charged for a long time with the cable removed, but discharges rapidly with the cable connected, you've got bad diodes in the alternator.

But, again, four guys say that the diodes are fine.

You could have a parasitic drain in some other circuit, though. I've seen batteries discharge through the conductive slime that accumulates on the plastic of the battery case.

 

[WalkingBlackBear]

I had the CTS go a couple of winters back ... truck ran fine until it got up to temperature though - THEN it started flooding itself out and running like crap. As long as I made it where I was going before the engine warmed up, it was okay. Lucky for me it was January in Canada. I'd be surprised if it was a CTS. Sounds more like an electrical gremlin, with the battery drain you're getting. And those can be a real b***h to find.

 

[95k150050]

I dod the parasitic draw by disconnect the negitive cable and use my dvm sat to 10 amps and measured the amp draw between the negitive terminal alternator and cable. And removed each fuse 1 at a time I checked every fuse and always had 1.24 amps across the battery to negitive cable. I checked the reading after I remover each fuse one at a time

 

[Schurkey]

I dod the parasitic draw by disconnect the negitive cable and use my dvm sat to 10 amps and measured the amp draw between the negitive terminal alternator and cable. And removed each fuse 1 at a time I checked every fuse and always had 1.24 amps across the battery to negitive cable. I checked the reading after I remover each fuse one at a time

1. What does "negative terminal alternator and cable" mean? I can't figure that out.
2. If the parasitic drain doesn't go away with any of the fuses, the drain is not part of the fused circuitry. The alternator diodes wouldn't be protected by a fuse, for example.

 

[95k150050]

Just checked AC voltage as described as soon as I touched the dBm to the alt. Output and to gtound it showed 2.6 but instantly dropped to 0.04 than 0.00

 

[95k150050]

Also idk if its normal but I disconnect the battery completly and measured the amp draw between the hot and negitive terminals and it had 1.24 with a completely disconnected battery

 

[95k150050]

1. What does "negative terminal alternator and cable" mean? I can't figure that out.
2. If the parasitic drain doesn't go away with any of the fuses, the drain is not part of the fused circuitry. The alternator diodes wouldn't be protected by a fuse, for example.

I ment between the negitive cable and negitive terminal. I hate this phone It automatically spells words

 

[Schurkey]

Also idk if its normal but I disconnect the battery completly and measured the amp draw between the hot and negitive terminals and it had 1.24 with a completely disconnected battery

You connected the amp meter between the battery terminals, and ONLY got 1.24 amps draw?

Should have been so much amperage that it'd pop the fuse in the meter.

If you're measuring 1.24 amps between the disconnected battery cable ends, I'd say the meter is faulty or needs to be "zeroed".

 

[95k150050]

Just checked AC voltage as described as soon as I touched the dBm to the alt. Output and to gtound it showed 2.6 but instantly dropped to 0.04 than 0.00

Is that normal?

 

[95k150050]

No I measured between the disconnect battery terminals on the battery not the cables