Northern Lights Generator Shuts off

I had my northern lights generator running this morning for about an hour when it suddenly shut off. I restarted it and it will only run with the pre-heat switch activated. Any ideas on what could be wrong? I checked all the fluid levels and everything is normal.

When you are holding the preheat button down, it will override the shutdown faults. First place to start is look in the manual and see what faults will cause a shutdown. Then work through those faults until you find the one causing the shutdown.

Check your oil pressure sensor and coolant overheat sensors for false activation. Typically they short to ground when operating normally. Check for loose wires to the sensors. Temporarily bridge them with a wire to find out which one is misbehaving. Make sure you do have raw water flow and oil pressure before you bridge the sensors.

Manual leaves a lot left to be desired. How can I determine if I water flow and oil pressure? I do not have gauges.

Check for water going out the tailpipe overboard. If you have a separator you might not see it. In that case check that the exhaust hose coming out of the unit is only slightly warm to the touch. If hose is hot, you may have lost an impeller or got a bag on sea water inlet.

Usually three switches on the safety shut down circuit; oil pressure, coolant temp and exhaust water temp. All are NO, normally open, so you can disconnect one at a time. Be sure the loose wire cannot touch the block (ground). Better yet, disconnect all three and see if it continues to run when you release the bypass switch.
Usual culprit is the oil pressure switch. Use the parts manual drawings to be sure you have the switch and not the sending unit.
Which model GENSET do you have?

Our N.L. genset has done that a couple of times. Both times it was due to pieces of kelp getting into the raw cooling water line and stopping the flow. Both times the kelp did not get as far as the water strainer.

Without gauges you are a bit restricted. I would disconnect just the oil pressure switch and see if it runs after release of the switch. If it does, then I would immediately shut it down and replace the switch.
If the new switch works then your oil p is ok so move on to the temp tests. Start up and put a IR gun on the spots near the two temp switches. Use the gun data to determine the problem if it shuts down again. Good luck. You can also screw a pressure gauge in at the tap for the switch or the gauge and confirm you have oil p.

Thanks for the replies I will start checking out the suggestions. I think it is water flow related will start there.

I have a 12kw NL generator that intermittently shuts down and sometimes will not crank. There are four relays in an onboard metal box that loosen in their sockets. Relays are for start, shutdown, run and bypass. Reseating them solved the problem. If not, try replacing them. I wedged them in with a wood bar and a strip of rubber, which helps, but over time they loosen up.

Have also had loose connections on the alternator and starter. Also replaced the shutdown solenoid. You should be able to hear the relays and solenoid activate when you press the bypass switch.

Good luck.

Its a northern lights M573k 8.0 KW, I am trying the obvious first, I think it may be water flow related. Is there a trick to unplugging those sensors?

if it is flow related you ought to be able to tell by the amount of water in the exhaust. Or use a IR gun on coolant and raw water passages on engine.
Unlikely it is actual low oil pressure but it could be. Since you do not have a panel w gauges then temporarily plugging a gauge into the port for the sender or the switch will work. Auto parts store item
The oil pressure switch and the coolant switch look kinda like spark plugs. Do you have the parts manual? If not, look on line for location. On my 12kw, Oil pressure switch is on front of engine, near top, with grey wire on top. Coolant switch a little harder to find, under alternator. Exhaust water screwed into elbow.
Does this help?

There was debris in the strainer and my impeller was toast. Changed it and cleaned the strainer and all is well. Thanks for all that replied.