During a recent repair the 8kw Onan Genset would not start. I pulled the pencil zinc head bolt out but the zinc broke off inside the raw water heat exchange chamber. So I pulled the end cap off the housing to get access to the chamber. It looked like the original so used a forceps to remove the remenants. Put it all back together and started the Genset to make sure everything was okay.

The engine fired up as usual and ran for about five minutes, then slowed down like it was running out of fuel, then stopped. Tried a few more times, and it seemed to want to start but on the fifth try, nothing. No click, no spin, dead. I noticed that when it ran that five minutes that very little raw water came out. My manual referenced a heat sensor on the hose leading into the mixing elbow that protects the hoses from exhaust temperatures, but its supposed to reset once it drops to 190 degrees.

I let everything cool down, poured water into the hose leading into the mixing elbow just in case the pump was having trouble priming. I checked the high amp (50) starter breaker and it showed 12 volts on both sides, drained some fuel out of the filter and it seemed clear. Then I had to leave for home.

Did I miss a fuse somewhere? The ten year old engine only has 280 hours on it. I did not use the starter motor that much to cause it or the solenoid to over heat or fail, I dont think. I ran out of time to check for voltage at the solenoid and motor.

Thanks to Victor Robert: I could not find the fuse. Used a mirror and flashlight all over the starboard side, but could not see it. I was getting voltage to the starter motor, so I bypassed the solenoid and the motor spun. I reached back and gently tugged on the two solenoid ignition wires and out pops the fuse holder. Sure enough it had blown...30 amps.

I closed the sea water intake seacock, pulled the intake water line off the engine and started to fill it with priming water. Then I heard water dripping, checked and sure enough, water was coming out of the sea water strainer. A few months ago when I cleaned it out for the season, I did not get a tight seal. When I started the motor for the first time it tried to bring in water but only got air and the exhaust temperature sensor shut everything down. The fuse blew when I tried too many times to crank the engine.

So, I secured the sea water strainer, primed the intake and discharge water lines with the seacock closed, and on the second short crank she fired up and ran like a charm. Then I opened the seacock, checked the exhaust port and plenty of coolant water was coming out.