Does anyone know where a "fuse block" or inline fuse would be hidden that, if blown, prevents power from the batteries from getting to the key switch. The only way I can crank the diesel is using a temporary wire from the "battery" post on the key switch to a positive battery post. I have the original manual which shows a wiring diagram but cannot locate the "fuse block." On my Oday 26, normally the key is turned "on" and the starter button is pushed to crank the diesel.
Starting Yanmar 1GM10
- Thread starter salty68dawg
- Start date
Don't really know where it might be located, but if you find one and the fuse is OK then it would be time to look at the wiring harness between the cockpit control panel and the engine. This harness is usually routed under the cockpit sole and around some sharp fiberglass bends. In older boats it is quite common that with hull flexing over the years the harness may become chaffed and wires leading to the solenoid or sensors may be cut or shorted. Usually a visual inspection of the harness around the places where it bends will show the damaged insulation and wires. Another possibility you may be experiencing is the dreaded "push the starter button and nothing happens" ; this is usually caused by old wiring which induces a drop in voltage with failure to activate the solenoid. A relay or rewire from panel to solenoid is the usual fix. Did not quite grasp your explanation on how you get the engine started but seems to me that the solenoid itself might be good. It would depend on where you use that jump wire at.
There is a little green plastic fuse box that holds a 30 amp fuse in a red wire that runs from starter to the key switch. The box is usually around the rear of the engine on the port side.. On my 3gmf it looks like the attached picture.. yours will look about the same.. It is a badly made little holder .. the fuse or the wire may have loosened.. 
The crappy inline fuse Kloudie mentions seems almost universal among builders, I've also located them on top of the engine and they are usually encased in copious amounts of black electrical tape such that you don't know it's there until you dig through the damn tape.
FWIW when the fuse gets loose while the engine is running, it keeps running.
FWIW when the fuse gets loose while the engine is running, it keeps running.