1991 Merc 135 V-6, Ser. No. 0D007523<br /><br />Since I replaced my switchbox and impeller, I am having a few issues with my motor I would like to resolve. I posted about the water temp in another thread because it seems to be an independent problem, but maybe all this is inter-related.<br /><br />I am seeing higher than what I believe to be normal water temps, and my RPMs seem to be high also. Is there a root electrical failure that could cause both gauges to be inaccurate?<br /><br />Do I need to do a complete tuneup after replacing a switchbox? I could swear my idle speed was about 700-800 rpm before the I had any problems, but I am not dead certain (I had to rebuild the water pump and replace the switchbox due to an overheat incident).<br /><br />I have a 12-volt automotive dwell/tachometer. Is there a place where I can connect it to the<br />ignition system to verify the boat's tachometer?<br /><br />If you have seen the other thread I just posted, you can see that I am having difficulty deciding where one issue ends and another begins, or if it's all really just one thing causing everything.
