I have a 2006 merc 3.0l and I just rebuilt the carb. There was all kinds of red gel in the jets. Wow! yesterday it never ran so good. Today, everything was going well, when I decided to switch to my "battery 2" When I opened it up, it started backfiring through the carb. Then I looked at my voltmeter, and it was pushing 15.5 I switched back to the other battery, and everything seemed fine. I opened it up a couple of times, but then came right in. So, I was thinking maybe my battery is shorting out or something, screwing up my spark. Could a bad battery be my problem?
