Engine will not crank and required charging time
For some details. 11 hp diesel engine. I have 2 batteries. I replaced the 1/2/all switch over the winter. After it was put in the water I have run the engine several times once when going sailing and the rest while working on the boat. The last time was 2 weekends ago I ran it for maybe 10 minutes. Only this past weekend I go down to do some things in preparation for this coming weekend when I am supposed to take my father for a sail.
I pulled out the water temperature sensor to clean it because when I replaced the water pump rotor thing like a month ago it was not pumping water and it got too hot. I got the water pump working but the temperature gauge had stopped working and cleaning it off is how I got it working the last time. I mention this for this question because I am think maybe a vapor lock? anyhow on to the question
After doing that I go to start the engine. I do the usualy prep, check oil, gear in nuetral and throttle about half way back. Turn the key to 1st stop check the gauge which reads roughly 12.5 then turn the key to the start position and I get nothing. There is no cranking sound at all. I recheck the gear and throttle and retry. Still nothing. I did notice that the voltage dropped slightly when I moved the key to the start position.
Any ideas? I was by my self at the time and tried to check some things electrically but it is impossible to turn the key and hold the multimeter lead in place. I am going down to the boat to diagnose this with my wife and would like ideas what to check for.
Also for the 2nd question How long should I run the engine to keep it charged. My boat is on a mooring with no external charging system. Once I get the engine started how long do I need to charge the starting battery to replace the energy used to start the engine?