My engine won't start


Old 08-06-08, 06:07 PM
Thread Starter
Join Date: Aug 2008
Posts: 1
My engine won't start

I have a 42 foot boat built in 1968 with a single screw 300 hsp Cummins Diesel. The motor starts fine on shore power, but the batteries don't seem to charge when cruising, and therefore, the boat has a heck of a time starting off battery power. What would be your checklist of possible problems?
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Old 08-06-08, 07:16 PM
Join Date: Jul 2008
Location: Montgomery MN
Posts: 541
I haven't worked on a diesel marine engine but I wuold start by checking battery voltage with the engine off. Then start the engine and check voltage with the engine running. Voltage should be above 12.0 with engine off and about 13 with engine running. If it isn't I would replace the alternator.
Old 08-07-08, 03:46 AM
Join Date: Apr 2007
Location: Near Buffalo, NY
Posts: 4,239
Another possibility: How old are the batteries? Shore power should also be charging the batteries. If they're left to charge for 10 to 12 hours, all of the batteries should come up to just over 13 volts. Check the batts for bad cells.

One more: an AC/DC fridge, a powerful stereo and other high-draw devices can suck batteries down in a hurry. If your starting battery isn't isolated from the aux batts, the starting batt can be drained along with the rest in as little as a couple of hours.

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